| A | B | C | D | E | |
|---|---|---|---|---|---|
1 | s | Name | Title | Abstract | Assignment |
2 | S03 | Darryl Z. Seligman | The Dark Comets | Small bodies are capable of delivering essential prerequisites for the development of life, such as volatiles and organics, to the terrestrial planets. For example, empirical evidence suggests that water was delivered to the Earth by hydrated planetesimals from distant regions of the Solar System. In recent years, an entirely new class of planetesimals has been discovered in the solar system: dark comets. The dark comets are small bodies which exhibit significant nongravitational accelerations only explainable by the outgassing of volatiles, without any evidence of cometary tails. These still-enigmatic objects are challenging our understanding of the behavior and properties of comets and asteroids. I will present recently published results reporting detections of nongravitational accelerations on seven additional dark comets. This set of dark comets reveals the delineation between two distinct populations: larger, “outer” dark comets on eccentric orbits that are end members of a continuum in activity level of comets, and smaller, “inner” dark comets on near-circular orbits that could signify a different different population. These objects may trace various stages in the life cycle of a previously undetected, but potentially numerous, volatile-rich population that may have provided essential material to the Earth. I will discuss prospects and challenges for discovering new dark comets with Rubin. | A10 - Simonyi-NSF Scholars: Unveiling the Universe |
3 | S64 | Sarah Greenstreet | Rubin Rocks: A web service for statistics on NEO dynamical histories | As current NEO surveys steadily increase the number of known objects, and with the expectation of significant contributions from the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST), our ability to understand the history of these objects correspondingly increases. Fitting numerical integrations to the observed population provides rich datasets from which the history of these objects can be inferred. Because such comprehensive integrations are computationally expensive, it is impractical to perform for the purposes of many smaller scale studies, such as the examination of a single NEO. We present here a web service for querying the statistical information on the dynamical histories of NEOs, including, but not limited to, source region probabilities, residence times, and time to initial entry, as functions of orbital elements. The service leverages comprehensive integrations of NEO orbits to provide a look up table of these statistics, which we provide access to through a publicly available API. | A10 - Simonyi-NSF Scholars: Unveiling the Universe |
4 | T01 | Jonathan Blazek | Simulation-based modeling with neural networks for galaxy IA and bias | Taking full advantage of high-precision cosmological data from Rubin LSST and other upcoming surveys will require both improved understanding of systematic effects and new statistical approaches. Two main systematics are intrinsic alignments (IA) and galaxy bias, which impact measurements of weak lensing and galaxy clustering. Current modeling often utilizes perturbation theory to extract information beyond the linear regime. However, future analyses will likely require fully nonlinear descriptions, especially for weak lensing measurements that rely on small-scale information. I will present recent and ongoing work to develop a simulation-based modeling framework for IA and bias, based on gravity-only simulations and semi-analytic models for galaxy occupation and IA. We are able to produce large, simulated volumes with realistic galaxy statistics, including flexible parameterizations for IA and the galaxy-halo connection. Using these simulations as training data, we have constructed neural network-based emulators to allow direct, simulation-based modeling of IA, lensing, and galaxy clustering. This approach will provide an accurate, nonlinear model for both standard lensing statistics (e.g. the two-point lensing and clustering correlation functions) as well as any beyond two-point statistic that can be measured from simulated data. | A10 - Simonyi-NSF Scholars: Unveiling the Universe |
5 | T02 | Alex Drlica-Wagner | Jump Starting LSST Proper Motion Science with DECam Observations | The Rubin Observatory’s Legacy Survey of Space and Time (LSST) will provide exceptional observations of the positions and fluxes of faint stars. Precise measurements of stellar proper motions are critical for understanding the formation and content of the Milky Way galaxy. However, these measurements require observations distributed over a long time baseline in order to detect the extremely small angular motions of stars. Early LSST observations can be combined with more than a decade of existing observations from the Dark Energy Camera (DECam) on the 4m Blanco Telescope to rapidly accelerate our ability to measure stellar proper motions. Furthermore, advanced techniques for improving the astrometric accuracy of ground-based observations developed for the Dark Energy Survey can be extended to the entire DECam data set and to future observations from LSST. We will present an overview of our efforts to use DECam to jump start proper motion science with LSST and projections for the potential reach of combined observations. Co-authors: Gary Bernstein, Robert Gruendl, Monika Adamow, Daniel Gomes, Chin Yi Tan, Vernon Wetzel | A10 - Simonyi-NSF Scholars: Unveiling the Universe |
6 | T03 | Gautham Narayan | Early Rubin science in the time domain | The Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) will discover millions of transient and variable sources at an unprecedented rate. This rich dataset will allow us to answer long-standing open questions on supernova progenitors and the nature of the most exotic transients, feedback and galaxy evolution, and cosmology. I will present an overview of four aspects of the analysis my group is involved in to enable early Rubin science 1) using AI to discover, classify and quickly follow-up young transients with Rubin and a network of ground- and space- based telescopes, 2) building the Rubin target-of-opportunity (ToO) system with the Scalable Cyberinfrastructure for Multi-Messenger Astrophysics (SCiMMA) group 3) finding and modeling gravitationally-lensed type Ia supernovae to study the Hubble tension and 4) studying the nature of dark energy with type Ia supernovae with the Dark Energy Science Collaboration (DESC). On behalf of The Young Supernova Experiment (YSE), The Scalable Cyberinfrastructure for Multi-Messenger Astrophysics (SCIMMA) team, The NSF-Simons SkAI Institute, and The LSST Dark Energy Science Collaboration (DESC) | A10 - Simonyi-NSF Scholars: Unveiling the Universe |
7 | T04 | Igor Andreoni | Establishing Multi-wavelength Time-domain Communities in the Rubin Era | Rubin will revolutionize our observations of the sky over time in optical, producing ~10 million alerts per night. Population studies using data from the LSST will have orders of magnitude more events to learn from. However, we can learn more about what explodes in the night by observing the same transient events at other wavelengths as well. Thus, we require the capability to identify needles in the haystack, and to get rapid follow-up observations performed before the transients fade out of detectability. This problem requires time-domain communities to adapt to the new era including ever more clever classification schemes, adaptation to what is learned in the first years of the LSST, and deeper collaboration than existed in previous surveys. We'll discuss these issues and one particular group which is approaching the problem in a new way. Co-authors: Eric Burns, Michael Coughlin, Ashley Villar | A10 - Simonyi-NSF Scholars: Unveiling the Universe |
8 | T05 | Colin Burke | Constraining supermassive black hole seeding and growth with AGN variability in the Rubin Era | Active galactic nuclei (AGNs) in dwarf galaxies (dwarf AGNs) are believed to host accreting intermediate-mass black holes (IMBHs). The demographics of dwarf AGNs are an important tracer of supermassive black hole (SMBH) growth, because their relic IMBHs act as a fossil record of SMBH seeding pathways at high redshift. Being ubiquitous across wavelengths and timescales, variability is useful for AGN identification and is an important probe of black hole accretion. I will present a new Bayesian hierarchical method and subsequent results constraining the local black hole occupation fraction, mass function, and accretion rate distribution with optical variability. Using simulation-based inference techniques, our observed results can be directly coupled to semi-analytic models of black hole growth to map-out the degeneracies between the initial mass function of high-redshift black hole seeds and their accretion and merger histories. This will provide useful predictions for the Vera C. Rubin Observatory and the Laser Interferometer Space Antenna (LISA). Co-authors: Priya Natarajan, Marla Geha, Vivienne Baldassare | A10 - Simonyi-NSF Scholars: Unveiling the Universe |
9 | S22 | Kevin Reil | Rubin System Integration and Test | Present the coming together of the summit portion of the Rubin system taking us to an-sky. | B02 - Commissioning: Detailed Status Update |
10 | S95 | Sean MacBride | Commissioning LSSTCam: From arrival at Cerro Pachón, First Light, and Beyond | The LSST Camera (LSSTCam), the largest ever constructed, arrived at the Rubin Observatory at the summit of Cerro Pachón, Chile, in May 2024. In the intervening time, LSSTCam went through a rigorous test, integration, and deployment program to achieve first photon on April 15 2025. I will review the different testing and integration efforts from 2024 to early 2025, and the performance of LSSTCam since first photon in April 2025. | B02 - Commissioning: Detailed Status Update |
11 | S14 | Gabriele Rodeghiero | Stray light findings and modeling with LSSTCam | The presentation will survey the stray light findings during the on-sky commissioning with LSSTCam. The assessment of stray light from optical and non-optical spurious reflections observed in the scientific images started early with the ComCam and continued with the LSSTCam. In parallel to the on-sky testing, a significant effort has been put into the modelling of the stray light with commercial ray tracing software. The stray light has important implications for the instrument signal removal task, and it can impact many science cases, such as the Low Surface Brightness objects. The talk will have a technical cut, but it will be conceived to be understandable to a general scientific audience. | B03 - Image Quality and Optical Peformance I |
12 | S53 | Tom J. Wilson | Validation and Verification of LSST Astrometric Positions and Uncertainties Using Operations Rehearsal Simulations | The verification of both measured positions and their corresponding covariances is a vital part of the validation of the LSST pipeline and its data products. Accurate measurements of the confidence with which centroids were measured, the first aspect of determining the belief in an astronomical object's true position given its measured position, are crucial to a wide range of astrometry-based research areas. In this talk I will describe preliminary verification work performed, using Operations Rehearsal data as the first large-scale LSST dataset on which comparisons between measured and true object positions can be measured, and the standard deviations of position differences compared with pipeline-derived covariance precisions. We find that single-visit reductions show good agreement between position scatter and uncertainty. Quoted Source table astrometric precisions matching on-sky separation residuals well once combined with a roughly 5 milli-arcsecond systematic uncertainty that varies weakly with on-sky source density, in line with theoretical expectations. We further find that Object table precisions have a systematic floor of 0.6 milli-arcseconds at bright magnitudes, in line with a reduction of square-root the number of co-added images over Source table systematic precisions. However, concerningly, Object table detections show a power-law dependency between quoted pipeline precisions and best-fit, data-driven astrometric uncertainties, in disagreement with expectations and in need of further investigation to identify the cause of. | B03 - Image Quality and Optical Peformance I |
13 | S05 | Christopher Stubbs | What we've learned about variability of atmospheric transmission above Cerro Pachon. | The Earth's atmosphere imposes a time-variable optical filter on images taken with the Rubin system. The Auxiliary Telescope (Aux Tel) has been used to determine the nature of the wavelength-dependent, time-variable aspects of atmospheric transmission. I'll report on the outcome of a workshop held in April 2025 that brought together experts to share knowledge and methods about variability in atmospheric transmission. | B04 - Photometric Calibrations |
14 | S16 | Michael Wood-Vasey | Measuring Precipitable Water Vapor with dual-band GPS at the Rubin Observatory | Precipitable water vapor (PWV) in the atmosphere creates significant, non-smooth absorption features, that affects measurements of all astrophysical objects. Achieving the high-precision and high-accuracy calibration necessary to achieve many LSST science goals, particularly in the time domain, requires knowing the atmospheric transmission function for each image. We have deployed a dual-band GNSS (GPS) system at the Rubin Observatory to provide complementary calibration to the spectra from the Auxiliary Telescope. Using publicly-available software, we convert GNSS measurements into PWV measurements and computing the water absorption part of the atmospheric transmission functions. We will present data and analysis from a re-analysis of a season of data from the similar system used during the Dark Energy Survey at CTIO, along with data from our hardware from its Northern Hemisphere commissioning, and the first results from running the system at the Rubin Observatory. | B04 - Photometric Calibrations |
15 | S51 | Agnieszka Pollo | The status of Polish IDAC and in-kind programme | I am planning to give a short overview of the status of the Polish in-kind program, progress and prospects. In particular, I will concentrate of the status of Polish IDAC and relations to the LSST Science Collaborations (in particular DESC and Galaxies). | B06 - IDACs, In-Kind Contributions, and You |
16 | S20 | Christopher Hernandez | Analyzing World-Public Alert Streams with the Pitt-Google Broker | The upcoming era of large-scale astronomical surveys such as the Vera C. Rubin Observatory’s Legacy Survey of Space & Time (LSST) and Nancy Grace Roman Space Telescope’s surveys of extragalactic and galactic fields will transform time-domain and multi-messenger astronomy research by generating world-public, high-volume alert streams of transient and variable sources. In this talk, I will introduce the Pitt-Google Alert Broker’s recent efforts to enable broad public access to, and scientific analysis of, alert streams from ongoing and upcoming astronomical surveys, including LSST, the Zwicky Transient Facility (ZTF), and the LIGO-Virgo-KAGRA (LVK) Collaboration. Our broker’s cloud-native architecture provides streamlined access to full alert streams via Google Cloud Pub/Sub, and enables users to filter them based on value-added attributes contributed by our pipelines. Our Python library, pittgoogle-client, allows users to access and interact with brokered data products, query enriched BigQuery tables, and enables the deployment of end-to-end science pipelines within their own Google Cloud projects. | B11 - Alerts, Brokers, and Follow-Up Systems |
17 | S07 | Mario Juric | Initial Rubin Solar System results: Performance, first discoveries, and expectations for SV | The LSST dataset will dramatically advance our understanding of the Solar System by delivering the largest catalog of small bodies to date. Final pre-operations predictions (Kurlander et al., in press) derived using a new, precise, simulation toolkit, Sorcha (Merritt et al., in press), point to an unprecedented yield of 5M+ main-belt asteroids, 100,000+ NEAs, 100,000+ Jupiter Trojans, 40,000+ TNOs, as well as tens of ISOs (among others). Many of these population will be well sampled and characterized early in the survey, transforming our ability to unravel the history and present structure of the Solar System. This talk will present the first public Solar System-related data from Rubin's early commissioning efforts. I will discuss the discovery yields, measured performance of the observatory so far, comparison to predictions, and talk through the expectations for further data during commissioning's SV surveys. With a steady stream of public solar system discoveries expected to start soon after RFL, small bodies are likely to be one of the first areas of highly impactful early science. We hope this talk will help prepare the Solar System community for those imminent opportunities, and illustrate to the broader audience the transformational capabilities Rubin is about to bring. | B13 - Solar System with DP1: Initial Results |
18 | S25 | Carrie Holt | Follow-up Observations of Moving Objects (FOMO): Community Coordination in the LSST Era | Rubin Observatory and LSST will dramatically increase the number of discovered solar system objects, creating a major challenge for follow-up coordination. FOMO (Follow-up Observations of Moving Objects) is a centralized platform designed to streamline this process. Built using the TOM Toolkit, FOMO provides a single reference point for tracking targets, submitting follow-up requests, and monitoring observation statuses across facilities. It supports automated ingestion from brokers and the MPC, real-time observatory status updates, and diverse observation types. FOMO will integrate with robotic telescope resources such as the LCO Network and larger facilities through AEON. The FOMO platform will enable the solar system community to effectively prioritize efforts, minimize duplication, and make the most of limited follow-up resources. | B13 - Solar System with DP1: Initial Results |
19 | S49 | David Trilling | SNAPS: The Solar System Notification Alert Processing System -- A downstream Solar System broker | I will present an update on SNAPS -- what we have been doing with ZTF, and our readiness for LSST. This presentation will have two parts: (1) SNAPS science and (2) a description of how SNAPS can be accessed and used by the community. | B13 - Solar System with DP1: Initial Results |
20 | S62 | Laura Buchanan | Research Announcements For The Solar System (RAFTs) | In collaboration with the Legacy Survey of Space and Time (LSST) Solar System Collaboration (SSSC) and the Canadian Astronomy Data Centre (CADC), the Can-Rubin team is developing a research announcement system for Solar System related discoveries. Named the Research Announcements for the Outer Solar System (RAFTs), this is a publication system designed to quickly issue short, citable announcements relevant to Solar System research. RAFTs are intended to address the unique needs of the Solar System research community in the era of large-scale surveys (such as LSST), providing a platform for timely dissemination of findings. Hosted by the CADC, RAFTs will be freely accessible and easily discoverable with permanent DOIs assigned to each. Each announcement will feature a machine-readable section to facilitate rapid follow-up, and will be integrated with the LSST community forum to encourage further collaborations and engagement. The system will also feature a moderation process to ensure high-quality and relevant publications. The announcements are expected to be brief, relevant, and may be urgent, though urgency is not a requirement for publication. The system is designed to be scalable, with the capacity to handle an increased volume of discoveries expected from the LSST. We will present a brief demonstration of the (in development) software interface, highlighting its user-friendly design and functionality for the community. | B13 - Solar System with DP1: Initial Results |
21 | S43 | Yen-Ting Lin | Evolution of Massive Red Galaxies in Clusters from z=1 to z=0.3 | A critical issue in studying the evolution of galaxy clusters is to find ways that enable meaningful comparisons of clusters observed at different redshifts, as well as in various stages of their growth. Studies in the past have typically suffered from uncertainties in cluster mass estimates due to the scatter between cluster observables and mass. Here we propose a novel and general approach that uses the probability distribution function of an observable–cluster mass relation, together with dark matter halo merger trees extracted from numerical simulations, such that one can trace the evolution in a self-contained fashion, for clusters chosen to lie in a specified range in mass and redshift. This method, when applied to clusters of different mass ranges, further allows one to examine the evolution of various observable–cluster mass scaling relations. We illustrate the potential of this method by studying the stellar mass content of red cluster member galaxies, as well as the growth of brightest cluster galaxies, from z= 1.0 to z= 0.3, using a large optically-detected cluster sample from the Subaru Hyper Suprime-Cam Survey, finding good agreement with previous studies. (AJ in press; arXiv:2503.13592) | B19 - Galaxies Science Collaboration |
22 | S45 | Simona Mei | The Rubin Galaxies Science Collaboration | This is a general presentation of the Rubin Galaxies SC as an introduction to the proposed SC breakout session. I will introduce the collaborations, welcome new members and show science highlights from this year. | B19 - Galaxies Science Collaboration |
23 | S52 | Steven Margheim | Accessing In-kind Contributed Telescope Access and Datasets. | (This really sits between a talk and a full 90 min session so submitting as a talk) This talk will offer details regarding the telescope facilities and datasets accessible to the Rubin community via the in-kind program. Comprehensive information will be provided concerning the availability of telescope access and the associated proposal process. Furthermore, an outline of available datasets and their respective accessibility will be presented. | B20 - Collaboration for complementary external datasets |
24 | S31 | Oleksandra Razim | Searching for anomalous variability with LSST and friends | As a survey that will observe unprecedented sky area with relatively high cadence, LSST promises to discover many new types of variable objects, periodic, stochastic and transient alike. However, at the moment, we do not have a reliable automatic or semi-automatic tool for novelty detection, at least not one that would be applicable to various science cases. This talk investigates which previously understudied parts of the parameter space will be well-covered by the LSST and can be the most promising in terms of anomalous variability discovery, as well as discusses which synergies with other surveys and what kinds of follow-up observations would maximize the scientific return for this task. | B22 - Machine Learning Applications for Inference, Discovery and Anomaly Detection |
25 | S63 | Siddharth Chaini | Anomaly hunting with Distance Metrics for LSST | Our physical understanding of the Universe has often progressed through serendipitous discoveries – anomalies, which we do not expect to discover, but whose discovery forces us to rethink our scientific assumptions and create new theories. The Vera C. Rubin Observatory will produce an unprecedented deluge of time-varying data, across timescales and volumes never seen before, which we expect will lead to entirely new discoveries. However, dealing with this data volume requires robust machine learning tools for the systematic discovery of unusual and anomalous phenomena. We present a novel approach to anomaly detection based on the use of distance metrics, leveraging our open-source tool DistClassiPy. DistClassiPy employs a variety of distance metrics to quantify the similarity between data points. We previously demonstrated its use to classify light curves in a high-dimensional feature space and showed that this method can perform light curve classification at state of the art accuracy with a fraction of the computational resources typically needed and with excellent scaling properties with both number of objects to be classified and number of classes [Chaini+2024]. We are now expanding its scope to anomaly detection. Our working hypothesis is that a truly anomalous object should be isolated in the feature space regardless of which distance is used to measure the proximity to known classes. We are testing the use of DistClassiPy as a robust and novel method for anomaly detection in LSST lightcurves. | B22 - Machine Learning Applications for Inference, Discovery and Anomaly Detection |
26 | S67 | Somayeh Khakpash | Automatic generation of magnification maps for lensed quasars and supernovae | Better modeling the microlensing variability in light curves of lensed quasars and supernovae enhances accurate measurements of time delays and the Hubble constant along with improving our understanding of quasars structure and the stellar mass distributions in distant galaxies. In the era of Rubin LSST, there will be thousands of events that need microlensing modeling. Traditional modeling approaches are computationally too expensive to support the analysis of the lenses at scale. In Khakpash et al. 2025 (K25), we developed a deep-learning model to reconstruct magnification maps of lensed quasars and supernovae from an informative latent space. In addition to facilitating the simulations, the latent space is directly connected to the physical parameters of interest, convergence (k), external shear (g), and smooth dark matter fraction (s) such that we will be able to move the analysis to a lower dimension space. We are leveraging contrastive learning to directly connect the latent space of the model developed in K25 with lensing parameters and stars’ positions in the lensing galaxy. This approach can be included in the analysis of the microlensing light curves of quasars and supernovae and enhance the search in the parameter space of k, g, s and finding the best-fit microlensing models. | B22 - Machine Learning Applications for Inference, Discovery and Anomaly Detection |
27 | S68 | Willow Fox Fortino | SNIHIL: A New Spectroscopic Supernova Classifier | After first light for the Rubin Observatory, the Legacy Survey of Space and Time (LSST) will discover millions of transient events and hundreds of supernovae (SNe) each night. While significant advances have been made in photometric classification, and only a subset of the LSST SNe will be observed spectroscopically, classifying SNe spectroscopically remains the best way to determine most subtypes of SNe. Traditional spectra classification tools use template matching techniques (SNID) and require significant human supervision. Two deep learning spectral classifiers DASH (Muthukrishna et al. 2019) and SNIascore (Fremling et al. 2021) define the state of the art, but SNIascore is devoted to minimizing the false positive rate of SN Ia-norm detections and DASH is no longer maintained and the original work suffers from contamination of multi-epoch spectra in the training and testing sets. We have explored several neural network architectures in order to create a new automated method for classifying SN subtypes, settling on an attention-based model. We benchmark our results against an updated version of DASH, thus providing the community with an up-to-date general purpose SN classifier. Our dataset includes ten different supernova types including subtypes of SN Ia, Core Collapse and interacting supernovae. We find that our attention-based model outperforms DASH, and we discuss the possibility that modern SN spectra datasets contain label noise which limit the performance of any classifier. | B22 - Machine Learning Applications for Inference, Discovery and Anomaly Detection |
28 | S92 | Peter Veres | Machine Learning Methods for Automated Interstellar Object Classification with LSST | Interstellar objects (ISOs) offer a rare opportunity to study material from other planetary systems. However, their extreme scarcity, brief observability, and the scale of data expected from the Rubin Observatory’s LSST pose significant challenges for timely detection and classification. We address this by applying machine learning methods to classify ISO tracklets within simulated LSST data. We evaluated several algorithms—including random forests (RF), stochastic gradient descent (SGD), gradient boosting machines (GBM), and neural networks (NN)—and found that GBM and RF models significantly outperform others in distinguishing ISOs from Solar System objects. Notably, derived Digest2 parameters proved more informative than direct observables such as astrometry and photometry. The GBM model achieved outstanding classification performance with a precision of 0.9987, recall of 0.9986, and F1 score of 0.9987. Our simulations suggest that, depending on nightly tracklet density, the classifier may flag from zero to several dozen ISO candidates per night—mostly false positives. However, true ISO tracklets are identified with near certainty, enabling reliable downstream analysis. These results support the integration of machine learning as a robust ISO pre-screening tool within the LSST pipeline. The approach facilitates rapid candidate identification for inter-night linking and follow-up observations, maximizing LSST's discovery potential for these rare visitors. | B22 - Machine Learning Applications for Inference, Discovery and Anomaly Detection |
29 | S06 | Sarath Satheesh Sheeba | Constraining the photometric redshifts of Quasars using Variability in the LSST Era | Quasars are known for their stochastic intrinsic variability at several time scales. Large sample studies help to improve the statistics and allow systematic studies of the time scales of variability and their relationship with the physical mechanisms driving these flux changes. With the upcoming large-time domain photometric surveys such as the Vera C. Rubin LSST, we expect to discover at least a few million new AGN. The large number of sources precludes the possibility of spectroscopic follow-up. Candidate confirmation and Photometric redshift estimation present an active research problem. I will present my thesis research results of a novel technique for redshift estimation that couples cosmological time dilation with intrinsic variability for inference. We used Gaussian processes to effectively model the optical light curves of AGN by constraining the structure function as a means to obtain their redshift priors.The redshift priors estimated from variability are then combined with those obtained from SED fitting to assess the impact of variability priors on redshift estimation. I will present a validation of this approach using the real data from SDSS, along with statistical analyses demonstrating improvements in precision, reduction in outlier fraction, as well as using simulated data to examine the effects of survey cadence and baseline on redshift estimation accuracy. | C01 - Active Galactic Nuclei Science |
30 | S09 | Swayamtrupta Panda | Exploring the potential for Active Galactic Nuclei (AGN) emission line delays using Rubin LSST | Active Galactic Nuclei (AGN) are variable sources, and analyzing the time delay of the strong broad optical emission lines relative to the underlying continuum is a crucial tool to investigate this important trait. This method aids in measuring black hole masses and deciphering the structure of the Broad Line Region (BLR) responsible for these emission lines, which can be extended to test existing cosmological models. The relationship between an AGN's absolute luminosity and the measured time delay contributes to these investigations. To facilitate time delay measurements, we have developed a pipeline that simulates the efficiency of such measurements using the survey strategies for the Vera C. Rubin Observatory's Legacy Survey of Space and Time. This code incorporates simulated light curves, incorporating strong emission lines (e.g., Hbeta, MgII, CIV), iron pseudo-continuum in the optical and UV bands, and contamination from starlight. By identifying optimal bands representing the continuum and dominant lines for a given redshift, the code enables the recovery of time delay under any available LSST cadences. Simulations are conducted for both the main survey and the Deep Drilling Fields (DDFs) using representative cadence strategies. The pipeline is modular, and multi-faceted, and can be used to determine time delays from actual data (e.g., ZTF), and can be easily extended to forthcoming surveys. I will highlight the salient features of the pipeline and discuss relevant applications and plans in anticipation of the first light of the Observatory. I will also share with you a new method that we have discovered that makes measuring the sizes of the broad-line regions in Type-1 AGNs, and hence their black hole masses up to 150 times faster! | C01 - Active Galactic Nuclei Science |
31 | S13 | Ethan Partington | Developing an SMBHB detection pipeline for LSST using null-signal templates | The “null-signal template” (NST) method is a new, data-driven approach for testing the significance of potentially periodic signals in quasar light curves. NST employs Bayesian statistics to differentiate between supermassive black hole binary (SMBHB) signals and the complex noise of individual quasars. It accounts for correlated noise and provides an alternative hypothesis for slow trends in the light curve using sinusoid-like variability with a randomized length for each period. NST is more computationally efficient than traditional significance testing methods, since it provides a testable alternative hypothesis to the periodic SMBHB signal without requiring simulations of quasar noise. I will share tests on the validity of the NST method using simulated LSST-like light curves and discuss the prospects for its application in the upcoming survey. I will also present preliminary results for a binary search with The Zwicky Transient Facility. | C01 - Active Galactic Nuclei Science |
32 | S17 | Christian Wolf | Australia-based AGN surveys and follow-up | We present recent Southern-hemisphere surveys for complete AGN catalogues including (1) the All-sky BRIght Complete Quasar Survey (ALLBRICQS), which provides a spectral atlas of a 99% complete sample of bright type-1 AGN, (2) XQz5, which provided a spectral atlas of a complete sample of z=[4.4,5.3] QSOs, and (3) three current works to establish a spectral atlas of a complete Southern type-1 and type-2 AGN sample derived from 6dFGS and updated with recent spectra. Using photometry from LSST and spectroscopic monitoring with the ANU 2.3m telescope, we conduct BLR reverberation mapping of some of the longest-lag QSOs in the sky to calibrate the R-L relation at high luminosity, in anticipation of comparisons with BLR size measurements with VLTI/GRAVITY+. | C01 - Active Galactic Nuclei Science |
33 | S23 | Zachary Steyn | Continuum Reverberation Mapping in NASA/ATLAS High-luminosity Quasars | The AGN Science Collaboration is gearing up to use the variable continuum emission from AGN to probe the structure of their accretion disks via reverberation mapping analysis. Assuming a hot inner light source irradiating the outer accretion disk, time lags between light curves in different passbands reveal light-travel times between their emission regions. Previous work on several low-luminosity AGN found 3x longer lag times than expected in standard disk theory. As a precursor study to LSST, we have analysed high-cadence light curves of 10 000+ bright quasars at redshift 0.3 to 2.5, using 2-band data from NASA/ATLAS over 7+ years. Given the large sample, we stack inference across the parameter space to improve lag detections. We find that the size discrepancy persists in our high-luminosity sample with some dependence on wavelength, possibly due to contamination from diffuse Broad Line Region and disk wind emission. In particular, we observe an inversion of the lag-luminosity relation at redshifts where our two filters straddle the Balmer jump. We also present tentative evidence that quasars with fast outflows, as evident in high CIV blueshift, have longer lags than normal quasars. | C01 - Active Galactic Nuclei Science |
34 | S60 | Maria Charisi | Searching for Supermassive Black Hole Binaries | Supermassive black hole binaries naturally form in galaxy mergers. They can be detected as quasars with periodic variability and LSST with the millions of quasars it will detect will provide a treasure trove for quasar periodicity searches. Previous searches in time-domain surveys have revealed promising candidates, but the stochastic variability of quasars can introduce false positives. I will describe the status of previously identified candidates. I will also describe a new data-driven method to assess the periodicity significance of quasars. This method does not make any assumptions about quasar variability, but estimates the null hypothesis using a non-periodic template and applying it to the data. We used this method to re-assess the statistical significance of the candidates identified in the Palomar Transient Factory. This method could relatively easily scale up for the massive LSST sample. I will also describe recent work, in which we demonstrate that traditional tools for periodicity searches, like the Lomb-Scargle periodogram, struggle to detect periodic signals in quasars and even more so, when these signals deviate from sinusoidal. This can be a significant limitation, as binaries likely produce more complex periodicity and previous searches may have missed the majority of such sources. | C01 - Active Galactic Nuclei Science |
35 | S82 | Hygor Benati Gonçalves | Exploring Quasar Variability With ZTF at $0<z<3$: A Universal Relation with Eddington Ratio | Quasars, powered by accretion onto supermassive black holes (SMBHs), exhibit significant variability, offering insights into the physics of accretion and the properties of the central engines. In this study, we analyze photometric variability and its correlation with key quasar properties, including black hole mass ($M_{\mathrm{BH}}$) and luminosities, using 915 quasars with $0\leq z<3.0$ from the AQMES sample monitored within SDSS-V. Variability metrics were derived from approximately 6-year light curves provided by the Zwicky Transient Facility -- ZTF, while SMBH masses and luminosities were obtained from the SDSS DR16 quasar catalog of \citet{wu2022catalog}. We identify a strong anti-correlation between variability amplitude and luminosity, which strengthens with redshift, and a redshift-dependent trend for $M_{\mathrm{BH}}$: a positive correlation at low redshifts, no significant correlation at intermediate redshifts, and an anti-correlation the highest redshifts. Our main finding is a robust anti-correlation between photometric variability amplitude and Eddington ratio, consistent across redshift bins. We present a general equation encapsulating this relationship, that appears to be almost free of redshift dependence, enabling predictions of quasar variability based on accretion parameters. The derived relation with the Eddington ratio provides a unified framework for interpreting variability in active galactic nuclei (AGN) and facilitates future studies of quasar variability using high-cadence surveys, such as the Vera C. Rubin Observatory's Legacy Survey of Space and Time -- LSST. | C01 - Active Galactic Nuclei Science |
36 | S08 | Paul Schechter | The Non-Simultaneous Flashes of Quadruply Lensed Supernovae: Dis-covery, Pre-covery & Re-covery | A "quadricity" has been assigned to every catalogued galaxy in the DELVE and DES surveys, using Falor's "astonishingly fast" *forward* closed form, giving a differentiable solution for the four image positions of an archetypical lens (the singular isothermal elliptical potential with parallel shear, SIEP+XS_||). The "quadricities" are calibrated using Euclid QR1 images. We propose to generate alerts for LSST transients *if* their positions put them inside the diamond caustics of near-certain quadruply lensed galaxies, allowing instantaneous followup imaging (and spectroscopy when warranted). The brightest of four lensed supernovae images is likely to be the second or third rather than the leading image or trailing one. The lightcurve for the leading image may be "pre-covered" from LSST archival exposures taken weeks or months beforehand. The trailing image, which is often the faintest, may be targeted for intensive followup weeks or months later. To assuage skeptics, we demonstrate that the SIEP+XS_|| potential successfully models quasars quadruply lensed by relatively isolated galaxies. | C02 - Transients and Variables Science |
37 | S39 | Riley Clarke | Measuring the Temperature Profile of an M Dwarf Flare with DECam and the Future of Flare Studies with LSST | We present the first derivation of a stellar flare temperature from single band photometry. Stellar flare DWF030225.574-545707.45129 was detected in 2015 by the Dark Energy Camera as part of the Deeper, Wider, Faster Programme. The brightness (∆g = -6.12) of this flare, combined with the high air mass (1.45 < X < 1.75) and blue filter (DES g, 398-548 nm) in which it was observed, provided ideal conditions to measure the zenith-ward apparent motion of the source due to differential chromatic refraction (DCR) and, from that, infer the effective temperature of the event. We model the flare's spectral energy distribution as a blackbody to produce the constraints on flare temperature and geometric properties derived from single-band photometry. We additionally demonstrate how simplistic assumptions on the flaring spectral energy distribution, as well as on the evolution of flare geometry, can result in solutions that overestimate effective temperature. As shown in Clarke et al. 2024, this novel technique will enable similar temperature constraints for large samples of objects in upcoming photometric surveys, notably LSST where the number of flare detections is expected to number in the millions over its 10 year lifespan. | C02 - Transients and Variables Science |
38 | S44 | David Sand | Shadowing LSST: Extremely Early Supernova Discoveries in the Nearby Universe | What are the explosion mechanisms and progenitor star systems of supernovae? In the early hours to days after explosion, supernovae provide clues to how they explode, and what their progenitor star systems were. Here we will discuss the science that will open up by `shadowing’ LSST with either Blanco+DECam or another moderate aperture telescope in the hours or day after the Wide, Fast, Deep survey has observed a nearby galaxy structure (such as the Virgo, Fornax or Hydra cluster). Opportunities that were possible only once or twice per year will increase by an order of magnitude, and will benefit from direct ties between discovery and follow-up facilities. We will discuss specific examples of ephemeral, but critical, signatures in early supernova data (e.g. early light curve ‘bumps’, flash spectroscopy, shock breakout cooling) and what they are teaching us about these cosmic explosions, with an eye towards what even deeper/fainter observations might provide. `Shadowing’ LSST will provide many opportunities and we hope to begin discussions of what might be possible. | C02 - Transients and Variables Science |
39 | S54 | Tatiana Acero-Cuellar | Creating a Light Echoes dataset with the LSST Science Pipelines | Light Echoes (LEs), the reflection of cosmic explosions off interstellar dust, are rare, faint, and extended variable sources that exhibit a variety of shapes, making them one of the hardest astrophysical transients to detect. While their detection provides unique opportunities to study transients and dust, their faintness, variability, and evolving morphology present challenges. The cadence and data volume of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) can enable the detection of rare and faint transients and variable objects, but the Rubin Alert Production pipeline focuses on point sources and will entirely miss these faint extended transients. Artificial Intelligence (AI) techniques are well-suited to the challenge of detecting LEs. However, successful models required a large dataset for training. In this talk, I will briefly introduce the theory behind LEs' observable properties and show how I am using the LSST Science Pipelines to inject LE simulations into DC2 data. The LSST Science Pipelines are both robust and yet flexible, allowing this workflow to be extrapolated to use with DP1/Rubin data. The ultimate goal is to generate a realistic set of simulated LE images to be used as training data for AI models designed for LE detection. | C02 - Transients and Variables Science |
40 | S56 | Shar Daniels | Fast Transients: Discovery and Characterization Potential with LSST | As transient science has advanced over the past decades, we have extensively mapped the week- and month- transient timescales and discovered phenomena that are characterized by increasingly faster evolution, shifting the horizon of the transient and variable sky yet to be explored. The serendipitous discovery and characterization of transients evolving on time scales of hours to days strains the capabilities of Rubin Observatory, yet many compelling scientific questions can be answered if we can enable coverage in these timescales and thus fulfill the promise of the fourth LSST science pillar: exploring the transient and variable Universe. I will present metrics for six new science cases that assess the LSST cadence’s capabilities of finding and characterizing fast transients. Previous LSST fast transient metrics were limited to the kilonovae, but we have expanded this work to include a morphologically diverse set of phenomena: Gamma Ray Burst Afterglows, Shock-Cooling Emission Peak in Supernovae IIb, M Dwarf Flares, Luminous Fast Blue Optical Transients, and Interacting H-poor Core-collape SNe (SNe Ib-n and Ic-n). The potential for LSST to provide transformational results for these science cases as a function of proposed LSST cadences will be discussed. | C02 - Transients and Variables Science |
41 | S69 | Xiaolong Li | Recovering the Light Curve of Eta Carinae’s Great Eruption Through Light Echoes | Eta Carinae (Eta Car) is one of the most massive binary star systems in our Galaxy. Its famous Great Eruption of the 19th century ejected about 20 solar masses, briefly making it the second-brightest star in the night sky. Eta Car is crucial for understanding the behavior of massive stars and giant stellar eruptions. However, the only direct observations of the Great Eruption (GE) were historical records of estimated visual brightness. The discovery of light echoes (LEs) from Eta Car provides a rare second opportunity to study this event using modern instruments. Using over 10 years of DECam imaging, we reconstruct the full 20-year light curve of the GE and compare it with the historical record. We also investigated the color evolution of the LEs, and found that the GE dramatically reddens during the 3rd peak, offering invaluable insights into the nature of the eruption. Based on the reconstructed light curve, we predict the future evolution of these echoes, which the Rubin Observatory’s Legacy Survey of Space and Time (LSST) is expected to observe in the coming years. | C02 - Transients and Variables Science |
42 | S74 | Daniel Perley | Orphan Afterglows and Dirty Fireballs with Rubin Observatory | A small subset of supernovae produce energetic, collimated jets that couple large amounts of energy (in excess of 10^51 erg) to a small amount of matter, accelerating it to relativistic speeds. The classical (and most extreme) manifestation of this phenomenon is gamma-ray bursts, but it is possible that a whole variety of other, related phenomena exist, including "dirty fireballs" (jets that are accelerated only to mildly relativistic speeds), or gamma-ray bursts seen off-axis, neither of which are expected to produce observable high-energy gamma-rays. Despite years of effort, previous optical surveys have so far failed to identify any unambiguous candidates of these phenomena - but Rubin's order-of-magnitude improvement in survey speed will be revolutionary in this regard, and within the first two years of science operations it should already place very strong constraints on the distribution of Lorentz factors and jet structure of collapsar jets, providing new insight into the nature of jet acceleration and collimation in these systems. | C02 - Transients and Variables Science |
43 | S48 | Claudio Antonio Lopez Cortez | Efficient Angular Mask Generation for Wide-Field Astronomical Surveys | The forthcoming Large Synoptic Survey Telescope (LSST) presents an unprecedented opportunity to study stars and galaxies through a massive dataset spanning about 20 billion images. However, the sheer scale of this data poses significant challenges to create angular masks suitable to isolate areas of interest, intersect footprints of multiple surveys, or generate synthetic sources at random positions. These are crucial tasks not only for analysis of large-scale structure such as two-point correlation functions or lensing, but also for a broad range of astrophysical investigations such as the mapping of galactic stellar streams and the identification of new Milky Way satellite galaxies. We present novel software tools and algorithms developed jointly with the LINCC Frameworks Collaboration to address these tasks by pixelizing catalog data and other geometric primitives in order to properly account for survey geometry, depth variations, completeness, among other effects. We will showcase how to build a complete mask for Subaru HSC-SSP+WISE surveys in less than a minute, and our progress toward a full angular mask for LSST. | C03 - Software and Tools for Data Analysis |
44 | S55 | Jeremy Kubica | LINCC Frameworks team DP1 Update | This talk will discuss recent work by the LINCC Frameworks team (LSST Interdisciplinary Network for Collaboration and Computing) on the application of software tools developed by our team to commissioning and DP1 data. We will discuss the use of LSDB to build lightcurve catalogues directly from Rubin DM data and then how these catalogs can be used to efficiently search for time varying sources. We will show some early results from applying LSDB to search for variable and transient events within the time series data from ComCam. We will also discuss the application of the KBMOD image-based shift and stack algorithm to ComCam images to find moving objects in the DP1 images. We will also discuss some of the expected scalability challenges as we look toward DP2. | C03 - Software and Tools for Data Analysis |
45 | S78 | Aritra Ghosh | Hyrax: A Framework for Scalable Machine Learning & Unsupervised Discovery in the Rubin Era | The Rubin Observatory Legacy Survey of Space & Time will produce an extraordinary volume of imaging and time-series data, creating both new opportunities and new challenges for discovery. To fully exploit this dataset, we introduce Hyrax, a scalable, modular framework designed to enable unsupervised discovery and anomaly detection at Rubin scales. Hyrax integrates multiple deep-learning-based approaches — including deep consistency learning, autoencoders, and adversarial anomaly detection — into a unified pipeline for the systematic exploration of extragalactic sources. It offers tools for latent-space clustering, similarity search, and interactive visual exploration of latent spaces. Hyrax is designed for flexible deployment across platforms, from individual laptops to the Rubin Science Platform. While ultimately intended for use on Rubin data, we are currently testing Hyrax on Hyper Suprime-Cam Wide data to validate performance and scalability. Early results demonstrate its ability to efficiently flag irregular extragalactic sources. By systematically surfacing such outliers, Hyrax will support a wide range of science applications, from probing dark matter substructure to mapping the cosmic evolution of galaxy morphology. We invite feedback from the community as we prepare for broader deployment and integration with Rubin-era workflows. | C03 - Software and Tools for Data Analysis |
46 | S04 | Priyanka Gawade | A Deep Learning Approach to Model Strong Gravitational Lenses from Ground-based Surveys | Modelling strong gravitational lenses provides valuable insights into galaxy-scale mass distributions and background sources, but traditional methods are time and resource intensive. We present a deep learning framework using convolutional neural networks, trained on realistic simulations, to rapidly estimate key lens and source parameters. We focus on the inference of the Einstein radius, and ellipticity components of the mass distribution along with the source position and its effective radius. To account for uncertainties and covariances, we extend this model with a Bayesian Neural Network, for posterior inference. We also demonstrate the approach on real strong lenses from ground-based surveys like Subaru HSC. This framework offers a scalable solution for analysing the large number of lenses expected from future surveys such as Rubin LSST. | C04 - Strong Lensing Science |
47 | S101 | Alma Gonzalez | Testing Rubin Image Quality for Strong Lensing Searches | We present an analysis of the impact of different image coaddition strategies on the search for strong gravitational lenses in the first Rubin Observatory data. If lens candidates are identified in a preliminary search, we examine how various coaddition selections affect their detectability. In the absence of detected candidates, we report results based on simulated (injected) lens systems. We also assess the influence of coaddition choices on key image-processing tasks, such as deblending, which are critical for identifying strong lensing features. | C04 - Strong Lensing Science |
48 | S18 | Anupreeta More | Testing LSST DIA pipeline on HSC imaging to identify lensed transients | Gravitationally lensed Type Ia Supernovae (SNe Ia) are uniquely suited to address the Hubble constant problem in cosmology. In addition to obtaining accurate time delays, the standard candle nature of SNIa also provides further constraints on the model of the lensing object. Finding such SNe in the ground-based imaging data from the upcoming Vera Rubin Observatory is a challenge. The multiply lensed images of the SN Ia can be identified as newly appearing sources in the Difference imaging which are close together. However, these lensed SNe images are expected to be unresolved for a majority of the lenses. We test the performance of LSST difference imaging (DI) pipeline on real HSC images in identifying the injected synthetic lensed SNe Ia. We recover about 70% of the unresolved lensed SNe. We expect several of these unresolved sources to appear extended in the differece images, and study the measured properties of DI sources that estimate their shapes to find any such markers of lensing. We also check whether using any of the DI pipeline flags can help in reducing contamination from unlensed transients. We also run association on the DI sources, and identify and classify various kinds of mis-associated sources and present some ways in which we can reduce the fraction of discarded true lensed images. Finally, we show that the color-magnitude criterion for identifying lensed SNe Ia works well on measured photometry of DI sources. | C04 - Strong Lensing Science |
49 | S19 | Anindya Ganguly | Discovering (Un)Lensed Kilonovae in Rubin-LSST: Simulations and Detection Methodology | Identification and characterization of (un)lensed Kilonovae (KNe) can be instrumental in improving our understanding of various aspects of cosmology and astrophysics, such as - measuring the Hubble constant, understanding the physics of the binary neutron star (BNS) merger, and studying the abundances of heavy nuclei elements. However, detecting (un)lensed KNe poses unique challenges due to their rarity and low brightness. Upcoming telescopes, such as Rubin-LSST -- with its deep imaging capabilities and wide field-of-view -- will provide a unique opportunity to observe these rare and faint transient events. Rubin-LSST will generate a deluge of data, making it essential to develop fast and efficient methods for identifying genuine (un)lensed events while minimizing false positives. To address this, we realistically simulate both unlensed and lensed KNe and test various strategies for efficiently detecting these events in the simulated light curve and image data. I will present the results of our latest simulations and detection methods. | C04 - Strong Lensing Science |
50 | S30 | Connor Stone | Caustics: a differentiable, GPU accelerated, gravitational lensing simulator | We present caustics, a tool to accelerate the analysis of gravitational lensing systems for the next generation of astronomical data. Caustics will enable precision measurements of dark matter properties, the expansion rate of the Universe, lensed black holes, the first stars, and more. In this talk I will discuss the benefits and challenges of how we used PyTorch (a differentiable and GPU accelerated scientific python package) to allow for fast development without sacrificing numerical performance. I will demonstrate some of the powerful capabilities that come with a differentiable lensing model. Caustics is already shaping new exciting discoveries in the search for dark matter, which I will detail in this talk. Fully Bayesian pixel level analysis of strong gravitational lenses is now possible. | C04 - Strong Lensing Science |
51 | S36 | Vibhore Negi | Generating mock simulated lensed images for the Rubin LSST | Strong gravitational lensing offers a unique tool to measure the current expansion rate of the universe and map the distribution of the dark matter and dark energy in the Universe. However, current studies are limited by the relatively small number of known strong gravitational lenses. The upcoming Rubin Observatory’s LSST is expected to uncover an unprecedented number of strong gravitational lenses. Several strong lensing pipelines are under development to search for lens candidates in LSST images and model them. However, there is a need to test and benchmark these various pipelines with realistic mock lenses. We have enhanced SIMCT, a tool to generate realistic simulated lensed images for all types of static lenses. This tool has enabled us to inject simulated lensed features around potential lensing galaxies in the real survey datasets like the Hyper Suprime Cam (HSC) Survey, by making use of mass models motivated by the light profiles of the real galaxies. We are also providing the simulated datasets for the 'Static lens search challenge' in the SLSC which will be crucial in testing and characterising various lens search and modelling pipelines. I will discuss the simulation techniques employed in the pipeline and share some results obtained with the HSC data that will be used for the static lens challenges. | C04 - Strong Lensing Science |
52 | S46 | Shenming Fu | Initial catalog query for LSST Lensed AGN | LSST will contain thousands of strongly lensed AGN, and their time delay measurements provide a cosmological probe. We derive an initial catalog query for finding lensed AGN candidates by injecting synthetic lensed AGN systems into DP02 images and reprocessing the images using the LSST Science Pipelines. By analyzing the resulting DIASources and DIAObjects, we test the completeness of lens detection and search for useful flags and quantities. Finally we provide suggestions for locating lensed AGN in the LSST Alerts, Prompt Products Database, and yearly releases. | C04 - Strong Lensing Science |
53 | S01 | Samuel Wyatt | ACROSS: Enabling Time Domain and Multi-Messenger Astrophysics with NASA Missions | The Astro2020 Decadal Survey recommended an investment in Time Domain and Multi-Messenger Astrophysics (TDAMM) as the top-priority sustaining activity in space for the coming decade. One aspect of NASA’s response to this recommendation is a pilot project, the Astrophysics Cross-Observatory Science Support (ACROSS) initiative, designed to provide support to both missions and observers as they pursue TDAMM science. Here, we present our observations of needs in the community and initial plans for ACROSS activities, including services to facilitate and improve cross-observatory follow-up planning and execution; a multi-messenger web portal with links to existing observatory resources, community tools, and information targeted for TDAMM General Observers. We invite discussion to better understand their needs and concerns as ACROSS progresses, and present our efforts on our web-portal and API that will have the potential to enable space-based and ground-based collaboration as Vera-Rubin operations rapidly approach. | C05 - External Synergies and Multi-Messenger Astronomy |
54 | S29 | Andjelka Kovacevic | Multiscale Astrobiology with LSST | The Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) presents a transformative opportunity to explore astrobiologically relevant phenomena. Here we overview LSST’s unique capacity to complement and support space-based observatories in the search for biosignatures and technosignatures. We propose the formation of a dedicated topical science team to coordinate community efforts and fully realize LSST’s potential in advancing astrobiology in the coming decade. | C05 - External Synergies and Multi-Messenger Astronomy |
55 | S38 | Viviane Angélico Pereira Alfradique | Dark Standard Siren Cosmology from O1-O4: current results from Legacy Survey and LSST-era prospects with galaxy weighting | Dark sirens are gravitational wave events without identified electromagnetic counterparts, where the identification of the source's redshift can be made using a statistical method in which probabilities are assigned to all galaxies within the localization volume as potential hosts, based on their positions. This method, alongside bright sirens from multimessenger detections like GW170817, has opened the era of multimessenger cosmology. We present a statistical dark siren measurement of $H_0$ for five gravitational-wave events detected during the O4a run: S231226av, S231206cc, S230919bj, S230627c, and S230922g. A deep learning method was used to estimate the probability density function of photometric redshifts from the DESI Legacy Survey data. Combining these with 10 previous events, we found $70.4^{+13.6}_{−11.7}$ km/s/Mpc, and when the 15 well-localized dark sirens are combined with the bright siren GW170817, we achieve a $H_0$ measurement with a precision of 6%. Additionally, we explore the systematic biases that could arise from: (1) adopting incorrect GW host probability weighting schemes, and (2) the incompleteness of a magnitude-limited catalog. Our results show that the bias can be controlled if: (1) an incomplete galaxy catalog is converted into a volume-limited catalog, and (2) the mismodeling of the GW host weighting scheme is mitigated in the presence of well-localized GW events. Finally, I will present some perspectives on cosmography with dark sirens in the LSST era. | C05 - External Synergies and Multi-Messenger Astronomy |
56 | S70 | Gregory Paek | Synergistic Classification of Transient with Rubin/LSST and the 7-Dimensional Telescope | The era of the Rubin/LSST will present unprecedented opportunities and challenges in transient astronomy, delivering millions of transient alerts each night. Effective and rapid classification of these events is crucial, particularly in identifying rare and scientifically valuable phenomena such as kilonovae associated with gravitational-wave counterparts. Here, we explore the synergy between Rubin/LSST’s high signal-to-noise broad-band photometry and the unique capability of the 7-Dimensional Telescope (7DT), which employs 40 medium-band optical filters to obtain detailed, single-epoch SEDs of transients. We have developed a machine learning-based multi-class classifier utilizing simulated 7DT photometry and demonstrate how adding Rubin/LSST photometry enhances classification performance by anchoring continuum measurements and highlighting key spectral features by 7DT. Specifically, Rubin's r-band data notably improve discrimination among transient types. Furthermore, we address the strategy of anomaly detection to robustly identify kilonovae, whose scarcity limits direct classification training. Our results highlight the complementary strengths of Rubin and 7DT, suggesting a powerful observational and analytical framework to manage transient alert streams in the upcoming Rubin/LSST era. | C05 - External Synergies and Multi-Messenger Astronomy |
57 | S86 | Cristina Andrade | The Effect of Vera C. Rubin Observatory Cadence Selections on Kilonova Detectability | The discovery of the optical/infra-red counterpart (AT2017gfo) to the binary neutron star gravitational-wave detection (GW170817), which was followed by a short gamma-ray burst (GRB 170817), marked a groundbreaking moment in multi-messenger astronomy. To date, it remains the only confirmed joint detection of its kind. However, many experiments are actively searching for similar fast-fading electromagnetic counterparts, known as kilonovae. Fortunately, the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) provides excellent prospects for identifying kilonova candidates either from, or independent of, gravitational-wave and GRB triggers. Cadence choices for LSST surveys are especially important for maximising the likelihood of kilonovae detections. In this work, we explore the possibility of optimizing Rubin Observatory's ability to detect kilonovae by implementing a fast transient metric shown to be successful with an existing wide field survey, e.g., the Zwicky Transient Facility. We study existing LSST cadences, how detection rates are affected by filter selections, the return timescales for visits of the same area in the sky, and other relevant factors. Through our analysis, we have found that employing baseline cadences and utilizing triplet families like presto_gap produced the highest likelihood of kilonova detection. | C05 - External Synergies and Multi-Messenger Astronomy |
58 | S87 | FNU Simran | Forecasting the H₀ Constraining Power of LSST with Bright Siren Simulations | The discoveries of gravitational wave standard sirens are expected to be significant during the LSST era. We want to determine the expected contribution of such discoveries to our cosmology analyses by quantifying the constraining power of this probe. For this analysis, we investigate to mitigate selection effects like sensitivity threshold of the gravitational wave detectors, depth of the electromagnetic searches and viewing angle dependency of the kilonova emission and how this affect the accuracy of Hubble constant measurements. Considering all these factors, we plan to determine a recommendation for the DESC collaboration that can inform the subsequent follow up strategies and the Target of Opportunity (ToO) searches. | C05 - External Synergies and Multi-Messenger Astronomy |
59 | S88 | Tomas Ahumada | Gravitational wave searches with the Zwicky Transient Facility | During the fourth observing run (O4) of the International Gravitational Wave Network (IGWN), the Zwicky Transient Facility (ZTF) has conducted a systematic search for kilonova (KN) counterparts to binary neutron star (BNS) and neutron star-black hole (NSBH) merger candidates. Here, we present a comprehensive study of the high-significance (FAR < 1 per year) BNS and NSBH candidates in O4. Our follow-up campaigns relied on both target-of-opportunity observations (ToO) and re-weighting of the nominal survey schedule to maximize coverage. We describe the toolkit we have been developing, Fritz, an instance of SkyPortal, instrumental in coordinating and managing our telescope scheduling, candidate vetting, and follow-up observations through a user-friendly interface. ZTF reached a median depth of g~20.2 mag. We describe our vetting strategy as no viable KN counterpart to any of the GW events was found. Based on the ZTF non-detections of the high-significance events in O4, we used a Bayesian approach, nimbus, to quantify the posterior probability of KN model parameters that are consistent with our non-detections. Our analysis favors KNe with initial absolute magnitude fainter than -16 mag. The joint posterior probability of a GW170817-like KN associated with all our O4a follow-ups was 64%. Additionally, we use a survey simulation software, simsurvey, to determine that our combined filtered efficiency to detect a GW170817-like KN is 36%, when considering the 5 confirmed astrophysical events in O3 (1 BNS and 4 NSBH), along with our O4 follow-ups. | C05 - External Synergies and Multi-Messenger Astronomy |
60 | S57 | Seneca Bahr | An Expanded Catalog and Atlas of Galaxies with Polar Structures: Preparing for the LSST Era | Galaxies with polar structures (PSGs) - systems featuring components photometrically and kinematically decoupled from the main stellar body - offer key insights into the role of accretion, mergers, and dynamical evolution in galaxy assembly. These rare systems, including polar rings and more complex morphologies, are often difficult to identify in shallow surveys due to the faintness or subtlety of their polar components and their complex geometries. Leveraging the depth of the DESI Legacy Imaging Surveys, we conducted a systematic search for PSGs across more than 383,000 galaxies from the Siena Galaxy Atlas. This effort has yielded over 700 new PSG candidates - doubling the number previously known and showcasing the power of wide-area deep imaging for rare object discovery. We present the general properties of this expanded sample. This dataset sets the stage for future discoveries with the Rubin Observatory, where LSST’s unprecedented combination of depth and sky coverage will enable structural studies of PSGs on a transformative scale. | C06 - Galaxies Science |
61 | S58 | Jose Antonio Vazquez-Mata | Morphological Classification of Galaxies Through Structural and Star Formation Parameters Using Machine Learning | We employ the XGBoost machine learning (ML) method for the morphological classification of galaxies into two (early-type, late-type) and five (E, S0–S0a, Sa–Sb, Sbc–Scd, Sd–Irr) classes, using a combination of non-parametric (𝐶, 𝐴, 𝑆, 𝐴𝑆 , Gini, 𝑀20, 𝑐5090), parametric (Sérsic index, 𝑛), geometric (axial ratio, 𝐵𝐴), global colour (𝑔−𝑖, 𝑢−𝑟, 𝑢−𝑖), colour gradient (Δ(𝑔 − 𝑖)), and asymmetry gradient (Δ𝐴9050) information, all estimated for a local galaxy sample (𝑧 < 0.15) compiled from the Sloan Digital Sky Survey (SDSS) imaging data. We train the XGBoost model and evaluate its performance through multiple standard metrics. Our findings reveal better performance when utilizing all fourteen parameters, achieving accuracies of 88% and 65% for the two-class and five-class classification tasks, respectively. In addition, we investigate a hierarchical classification approach for the five-class scenario, combining three XGBoost classifiers. We observe comparable performance to the “direct” five-class classification, with discrepancies of only up to 3%. Using SHAP (an advanced interpretation tool), we analyse how galaxy parameters impact the model’s classifications, providing valuable insights into the influence of these features on classification outcomes. Finally, we compare our results with previous studies and find them consistently aligned | C06 - Galaxies Science |
62 | S77 | Anja von der Linden | A Rubin view of Abell 360 | Rubin is designed to excel at weak-lensing measurements. Since one of the ComCam fields is centered on Abell 360, an intermediate-mass galaxy cluster at z~0.2, these data offer an opportunity for a first test of Rubin’s weak-lensing capabilities. We use the DRP data products to identify the cluster red sequence, select a sample of weak-lensing source galaxies, and test the PSF correction to arrive at a first weak-lensing detection by Rubin. | C06 - Galaxies Science |
63 | S84 | Vivek Kumar Jha | Testing SED Fitting Tools: Galaxy Properties from Prospector and BAGPIPES | Stellar population synthesis (SPS) modeling is central to converting LSST’s deep, multi-band imaging into quantitative insights about galaxy evolution. In this work, we present initial results from a comparison of two widely used SED fitting frameworks — Prospector and BAGPIPES — applied to photometric data for nearly 10,000 galaxies from the GAMA survey. Our preliminary analysis shows that Prospector can recover stellar masses with high confidence using as few as five optical bands. However, robust constraints on star formation histories require additional coverage in the near-infrared, underscoring the importance of wavelength leverage. We are developing a scalable, modular pipeline that enables batch processing of large galaxy samples, allowing us to systematically evaluate how modeling choices — including priors, SFH flexibility, and dust prescriptions — influence recovered parameters. Looking ahead, we aim to quantify systematic differences in age and metallicity estimates between the two frameworks, with a focus on understanding the role of prior sensitivity and model selection. These comparisons are critical for guiding the use of SPS tools on LSST-scale datasets. Our work is intended to inform the Rubin community on the performance, limitations, and interpretability of photometric modeling pipelines in the lead-up to full survey operations. | C06 - Galaxies Science |
64 | S85 | Zsolt Frei | Analyzing Images of Large Galaxies - Morphology | We have developed a Python-based tool for the detailed morphological analysis of well-resolved galaxies. Our method removes foreground stars, determines the position and inclination angles, fits structural components for spiral galaxies, models the radial light profile, and transforms the image into polar coordinates to produce a θ–log(r) representation. We then measure the opening angles of the spiral arms and analyze the power spectrum and flocculence of the galactic disk to determine the strength of the spiral structure. | C06 - Galaxies Science |
65 | S02 | Unnikrishnan Sureshkumar | Tracing the local environment of low surface brightness galaxies in the LSST era | Low surface brightness galaxies (LSBGs) being considered to account for a significant fraction of the total number density of galaxies play a crucial role in galaxy evolution. However, their connection to their local environment remains poorly understood, despite the well-established influence of the environment on the evolution of galaxies. In this talk, I will primarily present our recent results on the spatial clustering of LSBGs and the environmental correlations of various LSBG properties with the help of two-point correlation function and marked correlation function measurements. Our results are based on the LSBG galaxy samples from the Dark Energy Survey. Rubin LSST is expected to reveal an unprecedentedly large population of LSBGs. Our findings contribute to the advancement of low surface brightness science using the Rubin LSST. I will also present results from our previous studies that investigated how luminosities in optical to mid-IR bands, stellar mass, star formation rate, and galaxy merger probability are correlated with the local environment. We also compare our measurements from the observation with those from CosmoDC2, the simulated sky catalogue designed for Rubin Observatory LSST DESC. Additionally, I will present updates from our ongoing South African in-kind contribution in the LSST Galaxy Science Collaboration to cross-match the optical data from Rubin with radio data from MeerKAT. | C07 - Dwarf Galaxies and Low Surface Brightness Science |
66 | S10 | Laura Congreve Hunter | ID-MAGE: Identifying Dwarfs of MC Analog GalaxiEs | Dwarf galaxies are regarded as cosmological and astrophysical probes on small-scales, thus their discovery and characterization are among the most important goals in the field. Though much effort has been made in surveying Milky Way-mass galaxies and their satellite populations, the sample of satellites around lower-mass hosts is much less understood. I am presenting on the results of our survey to establish a statistical sample of unresolved dwarf satellites around Large Magellanic Cloud and Small Magellanic Cloud mass (10^8 ≤M* ≤ 10^10 M⊙) hosts. As part of the systematic search of the virial volumes of 36 low-mass hosts (4<d<10 Mpc), we have identified ~350 candidate satellite galaxies in the DESI Legacy Imaging Survey. With this sample, we have published quantitative constraints on the satellite luminosity function. I am presenting updates to our sample and the luminosity function based on our ongoing observational follow-up campaign. | C07 - Dwarf Galaxies and Low Surface Brightness Science |
67 | S21 | Erik Tollerud | Structural Parameters of Resolved Galaxies: connecting the small and large field limits | Rubin and the LSST will likely detect enormous numbers of resolved or semi-resolved dwarf galaxies in the Local Volume. However, *characterizing* them will be much more difficult than in the past due to crowding and a lack of spectroscopic data to confirm properties. I will discuss methods to address this, including 1) probabalistic structural modeling features that can connect alarge fields (i.e. Rubin) to small fields (i.e. HST or JWST), and 2) developments in spectroscopy with JWST to enable precision spectroscopy in fields too crowded for the ground. | C07 - Dwarf Galaxies and Low Surface Brightness Science |
68 | S28 | Aleksandr Mosenkov | Probing the Periphery of Edge-On Galaxies with Deep Imaging | We present a detailed analysis of structural asymmetries - lopsidedness, warping, and flaring — in the outer regions of edge-on galaxies from the Edge-on Galaxies in SDSS (EGIS) catalog, using deep optical images from the DESI Legacy Imaging Surveys. The sufficient depth of these surveys allow us to robustly detect and characterize low surface brightness features that trace dynamical perturbations and past interactions in the faint outskirts of galactic disks. We quantify the frequency and amplitude of these asymmetries across a statistically significant sample and investigate correlations with global galaxy properties such as mass, morphology, and environment. To interpret the physical origin of the observed features, we compare our measurements with radiative transfer models of galaxies from the TNG50 SKIRT Galaxy Atlas, which provides a theoretical benchmark for understanding disk instabilities and halo-disk misalignments in a cosmological context. Deep photometry is essential for this work, as it reveals the extended and diffuse structures that are otherwise undetectable in shallower surveys, enabling a more complete view of galactic evolution in the outer disk. The Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) will be crucial for future follow-up studies, providing deeper imaging that will dramatically enhance our ability to trace and interpret LSB structures around galaxies. | C07 - Dwarf Galaxies and Low Surface Brightness Science |
69 | S37 | Burcin Mutlu-Pakdil | A Deeper Look at Isolated Star-Forming Faint Dwarf Galaxies | The Local Group satellite dwarf galaxies are frequently used as benchmarks for testing galaxy formation and evolution theories on the smallest scales because they are the lowest-mass galaxies for which we have detailed observations. However, the vast majority of these dwarfs have been affected by the Local Group environment. If we want to understand the physical mechanisms driving the evolution of low-mass galaxies, it is essential to study pristine isolated dwarf galaxies beyond the Local Group as a control sample. Unfortunately, identifying such galaxies in the field is extremely challenging due to their extreme faintness. Until recently, Leo P was the only known example in this regime. With only one system, it is challenging to draw broad conclusions about low-mass star-forming galaxies evolving in isolation. In this talk, I will present new results from Hubble imaging of three recently discovered isolated, star-forming dwarf galaxies. These systems significantly expand the known population of isolated, star-forming dwarfs in the nearby universe, and provide a unique window into how star-forming faint dwarfs evolve in the absence of environmental quenching. I will discuss the implications of these findings in the context of reionization and the diversity of isolated dwarf galaxy evolution. | C07 - Dwarf Galaxies and Low Surface Brightness Science |
70 | S50 | Agnieszka Pollo | Low surface brightness galaxies and their environment: future with LSST | How many types of low surface-brightness galaxies exist, and how they are related to the underlying dark cosmic web and properties their host dark matter haloes, remains an open question. I will present a selection of new results from our group on relations between low surface brightness galaxy properties and their clustering, illustrating non-triviality of this topic, and the prospects for the almost coming LSST data. | C07 - Dwarf Galaxies and Low Surface Brightness Science |
71 | S73 | Kai Herron | Exploring the Dark Side: Uncovering Low-Surface Brightness Galaxies in the Dark Energy Survey | Observations from deep sky surveys have allowed us to uncover more of the universe than ever before. Hidden within these observations are elusive objects known as low-surface brightness galaxies (LSBGs), which are extremely faint, dark matter-dominated objects. Due to their faint nature, LSBGs have been incredibly hard to find, and the need for automated search algorithms has been emphasized in studies of these objects. Understanding the formation mechanisms, the true population of these objects, and what kind of environments they tend to form in are key to helping us fully grasp galaxy evolution and formation. Using observations from Y6 of the Dark Energy Survey, we have been able to develop tools to find these galaxies in a manner which emphasizes completeness of our sample of LSBGs while also removing noisy imaging artifacts. We present the results of our study, characterizing the completeness of our algorithm using simulated galaxies, the approximate size of our sample, and results related to understanding the nature of these objects, all of which will help us prepare for upcoming surveys such as LSST and Roman Space Telescope. | C07 - Dwarf Galaxies and Low Surface Brightness Science |
72 | S42 | Katarzyna Kruszynska | In preparation for the first gravitational microlensing events detected by LSST | While Rubin Observatory's LSST is expected to discover thousands of microlensing events, the average cadence is likely to be too low to characterize planetary and stellar binary events from survey data alone. Rubin's real-time alerts will enable us to trigger follow-up at other facilities to provide higher cadence photometry to constrain lightcurve features and spectroscopy to determine source properties. The OMEGA Key Project is a pathfinder follow-up program for microlensing across the Milky Way. Building on the infrastructure of Rubin's alert brokers, the project's Target and Observation Manager can conduct follow-up observations at scale. Observations of targets from existing surveys are mostly conducted by 1~m telescopes, and occasionally with the 2~m facilities, which are sufficient for currently operating surveys that produce microlensing alerts. However, Rubin's limiting magnitude in the Galactic Plane goes beyond the capabilities of small-scale observatories. I will present efforts to obtain time and build infrastructure for gravitational microlensing follow-up observations in the LSST era. For this purpose, I will focus on two Target and Observation Managers that will be used to select, prioritize, and request follow-up on LSST microlensing events: the Microlensing Observing Platform and the Microlensing Observing Program Manager, which is an in-kind contribution from the University of Heidelberg. I will give an update on the status of observations using the 4.1 m SOAR telescope during AEON queue nights and plans to obtain time on other relevant facilities. Additionally, I will discuss useful target selection and prioritization methods, as well as software designed to streamline these algorithms. Our goal is to improve our understanding of gravitational microlensing events in the upcoming LSST era. | C08 - Microlensing Science |
73 | S71 | Rachel Street | Enhancing Rubin Galactic Science With Roman | Rubin will provide groundbreaking photometric timeseries for millions of stars across the Galactic Plane, and detect an extraoridinary wealth of stellar variables and transients that will revolutionize our insight into galactic populations and evolution. Rubin's deep imaging will inevitably experience blending in these densely populated fields. This will lead to ambiguity in the identification of distinct objects and in the measurement of the spectral properties. However, as Rubin enters its second year of science operations, NASA will launch the Roman Space Telescope. This mission's primary instrument is the Wide-Field Imager, capable of deep (~24.5 mag in 57s), imaging between 0.62 - 2.13micron with a resolution that will rival that of Hubble. Among the surveys that Roman will perform are the Galactic Bulge Time Domain Survey and the Galactic Plane Survey. Data from both Rubin and Roman is highly complementary in wavelength, resolution and timescales. I will discuss how we can enhance the Rubin source catalog using Roman data to deblend crowded fields, and the corresponding improvements we can gain in variable and transient classification. | C08 - Microlensing Science |
74 | S75 | Natasha Abrams | Searching for Black Holes with Rubin Microlensing | Gravitational microlensing provides a unique opportunity to probe the mass distribution of stars, black holes, and other objects in the Milky Way. Historically, microlensing events have been discovered primarily in the Galactic bulge by surveys designed solely for that purpose. As we enter the age of visible all-sky surveys, such as that of the Zwicky Transient Facility (ZTF) and Vera C. Rubin Observatory (Rubin), we gain the ability to probe microlensing events throughout the Galaxy. This allows us to analyze galactic structure and how the stellar and black hole mass functions vary across the Galaxy. I will discuss some of the challenges we will face when searching for black hole microlensing. The source star can be magnified from ~100 days to over a year when it is lensed by a black hole and microlensing events occur most often in crowded fields. These effects can cause issues in both alerting events, which is critical for triggering follow-up opportunities, and in analyzing the bulk data releases. I will present these results in the context of the microlensing events we discovered in ZTF data and microlensing population simulations. The simulations were performed with PopSyCLE (Population Synthesis for Compact-object Lensing Events) to simulate microlensing events including black holes throughout the Galactic bulge and plane. | C08 - Microlensing Science |
75 | S102 | Erin Nothdorf | Searching for Supernovae Associated with Fast Radio Bursts with Rubin/LSST | Fast Radio Bursts (FRBs) are a rising class of energetic transients with diverse observed properties. While their origins are still known, the association of a Galactic magnetar with an FRB suggests that magnetars may be responsible for at least some FRBs. Since magnetars are predominantly born in core-collapse supernovae (SNe), and FRBs are often found near star-forming regions, a connection to young, recently formed magnetars is compelling. However, despite the discovery of thousands of FRBs to date, no past SN or historical optical transient has been definitively associated with any FRB. To provide direct evidence to this FRB progenitor model, recent work by Dong et al. (2025) systematically searched for positional and redshift coincidences between all known optical transients and well-localized FRBs. In this project, I build on that work by expanding the search to include future transient discoveries from Rubin/LSST. I also help develop and implement an alert system that routinely searches for possible FRB-SN associations. By understanding how Rubin/LSST will detect and report new transients, this project lays the groundwork for future efforts to uncover FRB origins in the upcoming era of thousands of VLBI-localized FRBs and Rubin/LSST optical transients. | Posters: Monday and Tuesday |
76 | S103 | Quinn Page Sullivan | Determining the Nature of an Unidentified X-ray source in the CDF-S Rubin LSST Deep-Drilling Field | In the 7Ms Chandra Catalog(Luo et al. 2017), only one source was detected significantly and had no counterpart. This source, XID 912 in the 7Ms Chandra Catalog, had a log, final no source probability of -13. XID 912 had 73.2 soft band counts (0.5-2.0 keV), no hard band counts (2.0-7.0 keV), and 77.3 full band (0.5-7.0 keV) counts. It had an effective power-law photon index of 2.9 and a simple power law fit of 3.1±0.5. The X-ray photon distribution was relatively uniform among the 7 Ms observations, with some low-amplitude variability apparent. At the time of the publication of the 7Ms Chandra Catalog, no multiwavelength counterpart in the radio, IR, NIR, or optical was found. XID 912 is also located 7.5” away from a known AGN, XID 916. There were two possibilities for the nature of XID 912. The first was an X-ray binary residing approximately 15 kpc away from XID 916. The other possibility proposed was that XID 912 was a high-redshift dusty AGN. Since the publication of the 7Ms catalog, new data in the U, R, I, J, H, K, L bands have been released, covering XID 912’s position. Additionally, the Rubin Observatory is set to receive first light soon and will give us excellent optical coverage as our source resides in one of its Deep-Drilling Fields(the Chandra Deep Field-South). With this added coverage in the optical, we will have coverage across the infrared, optical, and UV bands of our source, and we will construct the spectral energy distribution(SED) using aperture photometry. Then, we will apply SED fitting techniques to determine the origin of the source. | Posters: Monday and Tuesday |
77 | S104 | Alexander Mendoza | SED-based classification of accreting white dwarfs | Cataclysmic Variables (CVs) are binary systems in which a white dwarf accretes matter from a companion main sequence star, while AM CVns are accreting white dwarf binaries with helium rich donors. We will investigate whether is possible to distinguish between evolved CVs from AM CVn systems by analyzing their spectral energy distributions (SEDs) using archival data. Building on previous analysis of AM CVn systems, in this work we will focus on CVs near the minimum orbital period. We aim to complement the already available archival observations with incoming LSST data. We will also capitalize on LSST's capability to detect fainter objects to study the SEDs of systems that are too faint for current observatories. | Posters: Monday and Tuesday |
78 | S105 | Greyson Klein | Exploring Gaia-LSST Synergies for Milky Way Open Clusters | Star clusters are ideal laboratories for stellar astrophysics, providing a snapshot of a population of stars all at the same age and metallicity. These populations can help observationally constrain many outstanding questions about stellar and binary evolution. The Gaia mission has dramatically expanded the sample of known galactic open clusters, and yielded kinematic memberships, parallaxes, and high precision photometry for their populations down to a limiting magnitude of g~ 20. Rubin/LSST will offer unprecedented photometric depth and coverage of the Southern sky, and for a subset of galactic clusters the Gaia and LSST photometric and astrometric datasets can be combined to provide more complete and precise sampling of faint cluster members. Here we explore the Gaia cluster catalog of Hunt & Reffert (2023) to identify a sample of open clusters for which the blue straggler and main sequence turnoff regions can be jointly analyzed with Gaia and LSST photometry. These clusters will be high-priority targets for detailed analysis using currently available Gaia data, and for future study using upcoming Rubin/LSST data releases. | Posters: Monday and Tuesday |
79 | S106 | Lyrick Bartista | Accretion disc images from light curves | Active galactic nuclei (AGN) are incredibly useful objects to study, as they give insight to some of the most compelling physics surrounding black holes. The Event Horizon Telescope has been invaluable for observing Super Massive Black Holes (SMBH). However, it is somewhat limited in its effective range and observation capacity. Gravitational lensing provides a powerful probe for more distant astronomical objects that would otherwise remain unresolved. In particular, microlensing induces a variation in brightness of a background source due to stars in a foreground galaxy acting as lenses. This offers a unique opportunity to study the several specific regions of AGNs. When an AGN crosses a caustic (a region of high magnification) in a magnification map, the resulting high-resolution light curve encodes spatial information about the accretion disk on microarcsecond (10e-6) scales. Our project aims to exploit this by using light curve data from such caustic-crossing events to reconstruct two-dimensional images of AGN accretion disks. By modeling the time-dependent magnification of an accretion disk as it crosses a caustic region, we seek to recover fine structure in the disk's profile. This approach will not only resolve the size and shape of AGN accretion disks with unprecedented detail but also be able to constrain fundamental models of accretion disk physics and black hole structure. | Posters: Monday and Tuesday |
80 | S107 | Luigi Silva | Building a Compiled Spectroscopic Redshift Catalog for LSST-Related Science | We present the development of a compiled spectroscopic redshift catalog built from a comprehensive list of publicly available datasets, such as DESI DR1, OzDES DR2 and JADES DR3. As a first step, we propose a standardized quality flag schema inspired by the DES Science Portal, which translates the heterogeneous classifications from individual surveys into the OzDES flag system—ranging from 1 (no reliable features) to 4 (redshift with >99% confidence). Once the flags are harmonized, we apply the Combine Spec-z Catalogs pipeline—currently under development—to crossmatch and merge the datasets, leveraging parallel computing with Dask and potentially LSDB for efficient spatial crossmatching and duplicate resolution. The resulting high-confidence spectroscopic compilation will be integrated into the LSST Photo-z Server and will support the training and validation of photometric redshift models within the LSST ecosystem as part of LIneA’s Brazilian In-Kind Contribution to the Vera C. Rubin Observatory. | Posters: Monday and Tuesday |
81 | S108 | Ashley Ortiz | Detecting and Characterizing the Largest Cosmic Structures with Rubin/LSST | The most massive cosmic structures at z>2, destined to evolve into today's richest galaxy clusters, host extreme physical processes during their formation. These include intense starbursts, merger-driven black hole activity, gravitational cooling, and rapid quenching of star formation—manifesting as rare astrophysical sources such as Lyman-alpha blobs, submillimeter galaxies, quasars, and ultra-massive quiescent galaxies during Cosmic Noon, the peak era of galaxy formation. While current and upcoming facilities like JWST, Euclid, and the Roman Space Telescope are well equipped to study these sources in detail, identifying and confirming their large-scale environments—massive protoclusters—remains difficult due to their rarity. To understand how environment shapes galaxy evolution, it is not enough to detect these structures; we must resolve their internal composition—differentiating dense cores, extended outskirts, connecting filaments, and field regions—and determine where rare phenomena occur within the cosmic web. In this study, we explore optimal strategies for using Rubin/LSST data to detect massive protocluster candidates photometrically and combine these detections with targeted spectroscopy to map their three-dimensional structures. Our goal is to develop an efficient approach that will enable the discovery and detailed characterization of rare, massive protoclusters. This combined strategy will lay the groundwork for statistical studies of cluster formation and for understanding the role of large-scale environments in shaping galaxy evolution. | Posters: Monday and Tuesday |
82 | S109 | Alexis Ortiz | Unveiling Atypical Tidal Disruption Events with Rubin Observatory | Tidal disruption events (TDEs) occur when a star is sheared into a stream by the differential gravity of a black hole, producing luminous emission as the debris self-intersects, circularizes, and accretes onto the central object. These energetic transients serve as unique probes of massive black holes and the stellar populations and dynamics of nuclear clusters. While canonical TDEs involve the total disruption of a sun-like star by a one million solar mass black hole, there are a range of other parameters that can affect the observed transient: namely, stellar properties (especially density) and penetration factor (the ratio of pericenter to tidal radii). In this work, we consider TDEs from massive stars and from dense white dwarfs at a range of penetration factors with the goal of determining their observability with Rubin and what we can learn from a new, wider view of TDEs. | Posters: Monday and Tuesday |
83 | S110 | Jose "Diego" Monje Gastelum | Type Ia Supernova Rates in Dwarf and Giant Galaxies from the ZTF Bright Transient Survey | We present a measurement of the local volumetric Type Ia supernova (SN Ia) rate using 4,503 spectroscopically confirmed SNe Ia from the Zwicky Transient Facility Bright Transient Survey (ZTF BTS), covering redshifts up to z ≈ 0.14. To account for the survey’s flux-limited nature, we scale Hsiao spectral templates to a fixed absolute magnitude and simulate each SN’s brightness through the R-band filter across various phases and redshifts. Detection efficiency corrections are applied, accounting for high completeness (~80%) at low redshift, which declines significantly at higher redshifts. The volumetric SN Ia rate is computed by dividing the number of observed detections by the comoving volume as a function of redshift, the survey time, and the detection efficiency. We apply this calculation separately for different host galaxy populations, classifying hosts as giants or dwarfs based on an absolute magnitude threshold of M_i = -19 mag. A comparative redshift analysis within the BTS sample shows that supernovae in dwarf hosts are more frequently observed at higher redshifts than those in giant hosts, which may reflect a selection bias. Our calculated rates are compared with previous studies in the literature. Ongoing refinements of our efficiency corrections and observational completeness are expected to further enhance these measurements. | Posters: Monday and Tuesday |
84 | S111 | William “Alex” Huff | Synergy Between the TOROS and LSST Surveys | The Transient Optical Robotic Observatory of the South (TOROS) was designed to search for the optical counterparts of gravitational waves detections provided by LIGO. The survey uses two half meter telescopes (one to generate reference frames of the total Southern sky and one to provide high precision color follow-up of transients) which operate out of the Carlos Ulrrico Cesco Astronomical Station (EACUC) in San Juan Argentina. Starting in Fall of 2025, TOROS will begin providing color follow-up of important LSST transient events and interesting LSST variable stars. This work describes some of our initial estimates for how we will modify TOROS survey cadences to improve transient and variable star classification. | Posters: Monday and Tuesday |
85 | S112 | Colin Macrie | JWST and Ground Based Observations of the Type Ia Supernova 2023qov | I present observations and analysis of the “normal” Type Ia Supernova, 2023qov, from near explosion to nebular times (~280 Days post explosion). The well sampled early lightcurve from ground-based surveys, DLT40, ATLAS and Las Cumbres Observatory, shows the object to be normal, but slightly red and fast declining when compared to other SNIa. Two epochs of JWST near- and mid-infrared spectra reveal dust emission and line profiles which may hint to the progenitor and explosion mechanisms of thermonuclear supernovae. LSST will allow for earlier discovery of transients, as well as the collection of later light curve sampling than previously possible at a high cadence. | Posters: Monday and Tuesday |
86 | S113 | Daniel Cano Morales | Light curve classification of Superluminous Supernovae: from ZTF to LSST | Superluminous supernovae (SLSNe) are an extreme and rare class of supernovae. The Vera Rubin Observatory Legacy Survey of Space and Time (LSST) will discover a large number of SLSNe up to very high redshifts. I'll review some of the light curve classifiers that have been developed for the analysis of time-domain surveys like the Zwicky Transient Facility (ZTF) and LSST and their performance to discover SLSNe. I'll show results on the selection of SLSN candidates using our code to filter the ZTF alert stream with the ZTF/LSST broker Lasair and its annotator capability, which gives access to the NEEDLES and ALeRCE light curve classifications. We plan to extend this work to other LSST brokers (e.g. ANTARES and Fink) and light curve classifiers (e.g. Superphot+) and to apply the methods to the selection of SLSN candidates for spectroscopic follow-up programmes. | Posters: Monday and Tuesday |
87 | S114 | Anastasia Wei | Constraining Supernovae Progenitor Systems via Their Local Environments Within Their Host Galaxies | Wide-field time-domain surveys like the Zwicky Transient Facility (ZTF) have greatly accelerated supernova (SN) discovery rates, but for many subtypes, we still do not know exactly which stars produce the explosions that we observe. Host galaxy studies, particularly of explosion-site environments, provide a powerful avenue for understanding the stars that have exploded. We present a detailed local host galaxy environment analysis of 2,403 spectroscopically classified SNe of six subtypes with redshifts z ⩽ 0.03, discovered between 2018 – 2024 by the Bright Transient Survey (BTS) and Census of the Local Universe (CLU) projects within ZTF. We measure observed-frame surface brightness and colors within 0.4 kpc apertures using Pan-STARRS g, r, i, z, y imaging, and model host galaxy spectral energy distributions to derive local stellar masses. Our results indicate that SNe Ic preferentially occur in regions of higher surface brightness than other SN subtypes, with color distributions statistically indistinguishable from SNe Ib across all Pan-STARRs filters. This suggests SNe Ic prefer environments with higher stellar density rather than higher star formation rates. We also find that SNe II explode in significantly bluer environments compared to SNe Ib, Ic, IIb, and broad-line Ic; this difference likely arises from enhanced dust extinction for stripped-envelope SNe rather than intrinsic variations in stellar populations. The upcoming Legacy Survey of Space and Time (LSST) at the Vera C. Rubin Observatory, discovering ~2,000 new SNe nightly, will provide a far more complete and unbiased dataset to robustly characterize environmental differences among SN subtypes and place stronger empirical constraints on their progenitor channels. | Posters: Monday and Tuesday |
88 | S115 | Sarah Gelven | Measuring Precipitable Water Vapor for the Rubin Observatory | We have taken measurements from dual-band GPS system deployed at CTIO, KPNO, and Allegheny Observatory and successfully calculated precipitable water vapor in the atmosphere. Measuring PWV is important for accuracy and precise calibration of astrophysical observations with Rubin Observatory/LSST, particularly for source such as supernovae whose spectra have significant features and a science need for accurate and precise calibration. | Posters: Monday and Tuesday |
89 | S116 | Brittany Shavor | Impact of tree rings in LSSTCam | Using on-sky and in lab LSSTCam data, we characterize the lateral electric fields in LSSTCam sensors, such as tree rings or the mid-line break. These effects are indeed important to control as they displace electrons in the sensor in turn impacting the photometry and astrometry. We will thus assess their statistical impact, especially on measurements of the weak lensing effect. | Posters: Monday and Tuesday |
90 | S117 | Ruyi Xu | LSST, Dust and Complex Molecules | The Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) offers an unprecedented resolution map of cosmic dust in star-forming regions, key sites for the synthesis of complex organic molecules. Over its ten-year, six-band (u, g, r, i, z, y) survey of ∼20,000 deg², LSST will deliver deep, high-resolution photometry capable of detecting minute spatial variations in interstellar reddening. By constructing detailed extinction and color-excess maps across diverse Galactic environments, LSST can systematically identify dust-rich filaments and dense cores where complex organic molecules is most likely to develop. Combining LSST with with sub-millimeter and infrared molecular line surveys will enable cross-validation of dust column densities against observed abundances of species such as NH₃, C₂S, and HC₅N. Ultimately, LSST’s Looking forward, LSST could give more accurate coordinates to detect such molecules in the southern Hemisphere. | Posters: Monday and Tuesday |
91 | S99 | Aaron Romanowsky | Studying galaxies at low surface brightness with early Rubin data | The Vera C. Rubin Observatory presents unique opportunities to study the nearby Universe at low surface brightness (LSB) with deep, multi-wavelength imaging. I will present LSB objects such as ultra-diffuse galaxies in early Rubin imaging data. | Posters: Monday and Tuesday |
92 | S118 | Zac Coustier | Star Clusters Around Local Group Dwarf Galaxy NGC 6822: Subaru + Euclid Imaging and Keck Spectroscopy | Star clusters are a useful tool to study galaxy formation and stellar evolution. We present work on globular and extended clusters around the Local Group dwarf galaxy NGC 6822. We use deep, wide-field imaging from Subaru Hyper Suprime-Cam (HSC) and the Euclid Space Telescope as a preview of the data quality expected from the Vera C. Rubin Observatory and the Roman Space Telescope. We analyzed Keck Cosmic Web Imager (KCWI) spectroscopy of these clusters and measured radial velocities, ages (young and old), as well as metallicities. These results provide unique insights into the dynamical evolution of the galaxy and its star formation history. | Posters: Monday and Tuesday |
93 | S100 | Yumi Choi | 47 Tuc in Rubin Data Preview 1 | We present analyses of the early data from Rubin Observatory's Data Preview 1 (DP1) for the globular cluster 47 Tuc field. The DP1 dataset for 47 Tuc includes four nights of observations from the Rubin Commissioning Camera (LSSTComCam), covering multiple bands (ugriy). We address challenges of crowding near the cluster core and toward the SMC in DP1, and demonstrate improved star-galaxy separation by fitting fifth-degree polynomials to the stellar loci in color-color diagrams and applying multi-dimensional sigma clipping. We compile a catalog of 3,576 probable 47 Tuc member stars selected via a combination of isochrone, Gaia proper-motion, and color-color space matched filtering. We explore the sources of photometric scatter in the 47 Tuc color-color sequence, evaluating contributions from various potential sources, including differential extinction within the cluster. Finally, we recover five known variable stars, including three RR Lyrae and two eclipsing binaries. Although the DP1 lightcurves have sparse temporal sampling, they appear to follow the patterns of densely-sampled literature lightcurves well. Despite some data limitations for crowded-field stellar analysis, DP1 demonstrates the promising scientific potential for future LSST data releases. | Posters: Wednesday and Thursday |
94 | S12 | Bryce T. Bolin | Twilight Discovery of near-Sun Asteroids and Naked-eye Comets at Palomar Observatory | While the majority of solar system objects discovered by wide field surveys are ordinary, they also provide the opportunity to discover hidden gems such as interstellar objects, near-Sun asteroids, and bright comets. These provide opportunities to characterize extrasolar planetesimals, search for new sources of asteroids in the inner solar system, and study the composition of the protoplanetary disk. I will describe survey techniques used to discover these hidden gems in observations of the near-Sun sky during twilight in current and next-generation surveys, such as the Zwicky Transient Facility and the Rubin Observatory. I will describe three examples of twilight solar system results: 1.) the discovery and follow-up observations of (594913) 'Ayló'chaxnim, the first known asteroid possessing an aphelion entirely within the orbit of Venus, 2.) the recovery of interstellar comet 2I/Borisov, and 3.) the discovery of naked-eye comet C/2022 E3 (ZTF). I will discuss the behind-the-scenes work of using machine learning in these results and their implications for the formation of the solar system and the composition of extrasolar and solar system planetesimals. | Posters: Wednesday and Thursday |
95 | S15 | Christina Adair/Douglas Tucker | Absolute Photometric Calibration in Rubin Data Preview 1 with HST CalSpec C26202 | The ComCam commissioning observations of the ECDFS field included the HST CalSpec standard C26202, which is faint enough to avoid saturation in ComCam science images. This standard was previously used for the absolute AB calibration of DES DR2. Two analyses were performed on ComCam data: (1) measurement of the absolute system throughput for the u,g,r,i,z,y bandpasses, and (2) determination of AB magnitude offsets for these bandpasses. The absolute system throughput analysis involved calculating expected counts for C26202 across various airmasses and comparing them with observed counts. The AB offsets were derived by comparing calibrated ComCam AB magnitudes with synthetic magnitudes. Results indicate consistency between measured and predicted counts. Here we present results from the final Data Preview 1 processing. | Posters: Wednesday and Thursday |
96 | S24 | Claudia M. Raiteri | Chasing blazars with Rubin-LSST | Blazars are known as extremely luminous and variable active galactic nuclei. Their properties are due to relativistic motion of particles in a plasma jet pointing towards us, with consequent Doppler beaming of the emitted radiation. The central engine is thought to be a supermassive black hole of the order of billion solar masses. However, blazars are hosted in early-type galaxies, which are expected to be the result of galactic mergers, so they may actually be powered by a binary system of black holes, which should be detectable through periodic modulation of the jet emission. Blazars are also formidable particle accelerators and can be responsible for at least some of the very high-energy neutrinos detected by the IceCube neutrino observatory. Rubin-LSST will be a powerful tool to study blazars as a population up to unprecedented redshift and catch single objects during peculiar activity states that can reveal the underlying physics. These strengths will be exploited by the Blazars Follow Up Task Force born within the AGN Science Collaboration. In this poster we will review the milestones that we plan to reach as LSST progresses. | Posters: Wednesday and Thursday |
97 | S26 | Mahmud un Nobe | Cosmic evolution of supermassive black hole mass and their accretion rate in the last 10 billion years (z~2). | Supermassive black holes (SMBH) lie at the heart of nearly every large galaxy, and their appearance varies greatly depending on their properties, our point of view, or a combination of these two factors. Because of our incomplete understanding of how matter is distributed around these black holes, it is unclear which factor dominates in regulating this matter. Previous work indicates that the factor that regulates the distribution of matter around SMBH is its accretion rate, at least in the local Universe. We are extending this work further back in time to see if the scenario is consistent throughout the evolutionary history of SMBH. Specifically, we used a sample of 998 X-ray-selected SMBH from the Stripe82X survey, for which we obtained the spectroscopic masses and the obscuring column densities. Then using bayesian Markov Chain Monte Carlo (MCMC) model, we estimate the distribution function for accretion rates, black hole masses, and X-ray luminosities of unobscured SMBH in the last 10 billion years (redshift up to 2). | Posters: Wednesday and Thursday |
98 | S27 | Wendy Mendoza | Compact Objects and the Physics of Accretion Survey (COPAS) | Accreting white dwarf (WD) binaries, including cataclysmic variables (CVs; H-rich binaries) and AM Canum Venaticorum (AM CVn; He-rich binaries) stars are systems in which a WD accretes material from a close companion. These systems are important sources of gravitational waves and are essential for studying stellar evolution and accretion physics under extreme conditions. In this work, I will discuss how using high-cadence observations from the Transiting Exoplanet Survey (TESS), we have identified a variety of outbursts profiles for several of these accreting systems with unprecedented detail. Our findings indicate that several of these objects belong to the elusive family of AM CVns. I will also mention how our TESS results will help us to implement strategies to identify and characterize both classes of accreting white dwarfs using data from the Legacy Survey of Space and Time (LSST). | Posters: Wednesday and Thursday |
99 | S33 | Peter Plavchan | The NASA Landolt mission | The NASA Landolt mission is an astrophysics PIONEERS program small satellite that will provide significant improvement in the accuracy of photometric measurements of absolute stellar fluxes. This will be accomplished with a NIST-calibrated suite of single-mode fiber-fed laser beacons. The satellite will be placed in a near-geosynchronous orbit with a one-year primary mission with launch no earlier than October 2028. After commissioning, Landolt will point to scheduled ground-based observatories for calibration observations. Landolt has a level 1 mission requirement to improve the photometric accuracy to <0.5% at visible and near-infrared wavelengths for >65 target stars. Such measurements can only be achieved by a space-based orbiting artificial "star", where the emitted physical photon flux is accurately known. Accuracy of absolute flux zero points is now the leading error budget term in the characterization of stars, be they standard stars or exoplanet hosts. Landolt will enable the refinement of dark energy parameters, improve our ability to assess the properties of terrestrial worlds, and advance fundamental constraints on stellar astrophysics and evolution. | Posters: Wednesday and Thursday |
100 | S59 | Melissa DeLucchi | LSDB: LINCC Frameworks software for analysis of large catalogs | Rubin data will introduce unprecedented challenges in the joint analysis of astronomical datasets. We present Hierarchical Adaptive Tiling Scheme (HATS, formerly referred to as hipscat), an advanced spatial partitioning of large datasets using Parquet storage. LSST Interdisciplinary Network for Collaboration and Computing (LINCC) Frameworks has built the LSDB framework on top of HATS format for efficient and scalable cross-matching and analysis of big datasets, to enable catalog builders to provide archival and future catalogs in HATS format. We have created a global partnership to provide survey data in HATS (including STScl, IPAC, CDS, and S-PLUS), and provide the Rubin DP1 catalog to rights-holders. In this poster, we will showcase: an overview of the tiling scheme and its power in driving massive cross-matches; an introduction to the LSDB API; a demonstration of its use on DP1 and crossmatches to publicly-available HATS catalogs like Gaia, ZTF, and PanStarrs. | Posters: Wednesday and Thursday |