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IGRINS-2 for Gemini Telescope:

Development and Early Performance

Young Sam Yu

and IGRINS-2 Team

21 Aug. 2024

KGMT-SP User Meeting

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Contents

Introduction

Background
IGRINS

Development

Project milestones
The team
Key upgrades from IGRINS to IGRINS-2
AIT and instrument acceptance

First light and early performance
Upcoming schedules and tasks

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Background

The IGRINS-2 project was initiated as part of the full participant agreement between KASI and Gemini Observatory in July 2018. Specifically, it is stated that KASI will provide Gemini Observatory with an instrument very similar to the original IGRINS.

Gemini's international headquarters @ Hilo

Gemini North

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IGRINS

Immersion GRating INfrared Spectrometer
KASI & Univ. of Texas Austin collaborative development, 2009 - 2014
Highly sensitive, large λ coverage in NIR 1.49 – 2.46μm
High resolving power ~ 45,000 (7 km s^-1)
5″x 0.34″ Slit (@ Gemini)
H2RG sensors, VPH gratings
Compact size ~ 1m x 0.6m x 0.4m

Optical Design

Cold Stop

Mace et al. (2018)

Immersion Grating

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Key Science Requirement

Feature	Requirement
Spectral Coverage	1.49-2.46 μm
Slit length (8.1-m telescope)	5″ (5.5″ order spacing)
Spectral Sampling	3 pixels at 40,000
Spatial Sampling	0.1″ on the 8.1-m
Resolving Power (highest)	50,000
Rθ (slit loss <50% in median seeing, R=30,000 goal at R=50,000)	21,800
Actual Resolving Power for 90% (100%) of the band at R=40,000	36,000 (32,000)
Additional Continuum within extracted stellar spectrum	<10%
Ghost intensities	<0.25% of main line
Spectral flattening	0.25% over R/20
Thermal background from dewar internal optics	<0.01 e/s
Window emissivity	<2.5%
Out of band scattered light	<0.01 e/s
Wavelength Stability	1 km/s (1/2 pixel)
Slit-less Throughput (on blaze)	0.23

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Science Cases

Utilizing NIR, high-resolution spectroscopy with high sensitivity.

Young Steller Objects (YSOs) Evolution

Fundamental stellar properties of T_eff, log g, B field
CO, Na, Mg, Ti, Ca, Al, etc.

YSO Disks

CO from inner disk, H₂O, accretion features (Br_gamma)

Stellar Population and Chemical Evolution

Metallicity from various species, carbon to oxygen ratio of metal poor star

RV Studies

Binaries, Brown Dwarf, Yong Planet with ~1 km/s RV precision

Interstellar Medium (PNe, Supernova Remnants, PDR)

Ro-vibrational H_2, UV-pumping, shocked emissions

Galactic Center
Solar System Bodies

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Project Milestones

Milestone	Date	Comment
Kick-off Meeting	2020-03-30
Final decision on optical design options	2020-05-30
Critical Design Review (CDR) for Upgrade	2020-10-30
Production Readiness Review (PRR)	2021-03-30
Slit-Viewing Camera Lab Image Acquisition (Start)	2022-03-30
Spectrograph Integration and Testing in the Lab (Start)	2022-09-30
Acceptance Test & Review	2023-07-24~28	Gemini team at KASI in Korea
Pre-shipment Readiness Review	2023-08-16~17
Shipping Instrument from KASI to Gemini	2023-08-28
Post-delivery Acceptance Review @ Hilo	2023-09-18~22	KASI team at Gemini North in Hilo, USA
First Telescope Integration Run	2023-10-02~09	KASI team at Gemini North in Hilo, USA
Second Telescope Integration Run	2024-01-03~07	KASI team at Gemini North in Hilo, USA
Commissioning Readiness Review	2024-03-27
Commissioning Run	2024-04-23~29
Systems Verification Run	2024-07-17~23
Normal Operation (Shared risk mode)	2024-11 (TBD)

COVID-19 pandemic

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The Team

+ more people helped with the project both at Gemini and KASI!

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IGRINS and IGRINS-2

The instrument specs remain the same
Reasons for change

It’s been 10 year since IGRINS was developed, some products are discontinued
To upgrade (within given timeline)

Major Change and Upgrade

Optics: Slit-view FoV upgrade

from incomplete (~60%) to full disk

Mechanics: Light tightening

One-body radiation shield, connectors, cooler assembly

Electronics: MACIE detector controller

Interface board for the original IGRINS (JADE2) has been discontinued by Teledyne.

Observing Software and Data reduction pipeline

Fully integrated with the Gemini SW system

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Summary of Requirement

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Summary of Requirement

SW GIAPI rqmt

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Verification Plan: Method

Total	Inspection	Analysis	Test	Demonstration
163	79	15	55	14

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IGRINS-2 Full Assembly

IGRINS-2 full assembly (June 2023)

H

K

S

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AIT Flow

Phase A

Phase B

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AIT: detector focus alignment

pin-hole in cal box

pin-hole image at slit-view camera

pin-hole + flat lamp image at sci. detector

adjustment of detector mount

yaw

pitch

defocus

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AIT: detector focus alignment – H band

Pinhole + flat lamp

IGRINS-2

Original IGRINS

FWHM:

1.21-1.48 pixel

*region 7 is 1.69

Rqmt: FWHM of the PSF of a point source < 1.53 pixels

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AIT: detector focus alignment – K band

Pinhole + flat lamp

IGRINS-2

Original IGRINS

1

2

3

4

5

6

7

9

8

FWHM:

1.23-1.45 pixel

Rqmt: FWHM of the PSF of a point source < 1.53 pixels

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Cooling Curve – Pre-shipment

Over 35 cycle was conducted during the lab test
Cool down / warm up time and the temp range is well satisfied the requirement.

Cool down: ~38 hr

Warm up: ~43 hr

Start: June 19 23:09

End: June 21 13:00

Start: June 30 14:53

*End: July 2 09:55

*Completion of warm-up was defined as when all parts were over 290 K. (temperature sufficiently higher than the dew point of the day, 285 K)

**Discrete feature around June 30 in the plot: bench temperature adjusted the during the cool state for test purpose.

**

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Pre-delivery Acceptance @ KASI

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Post-delivery Acceptance @ MK summit

Calibration system

Flat/ThAr Lamp
Pin-hole
Dark mirror
USAF target

IG-2

Chamber

TC rack

Computers

Gemini North summit 2nd floor lab

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IGRINS-2 Installation

IGRINS-2 on Gemini North (October 2023)

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IGRINS-2 Installation

IGRINS-2 on Gemini North

(October 2023)

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Summary of on-sky runs

1st and 2nd telescope integration run

10/4-10/8 2023 and 1/3-1/7 2024
~40 hours telescope time
Various sky conditions IQ 20/70/85/Any, CC 50/70/Any
Verifications of key requirement and basic tests
Software tests - Engineering tool, instrument (slow) guiding, ObsApp (Slit-view camera interface) w/ Gemini SeqExec

Commissioning (4/23-4/29, 2024)

~25 hours telescope time
Software test and acceptance
Handover to Gemini operations team
Data reduction demo

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Commissioning Task list

IGRINS-2 Requirement ID	Title	On Tel/Sky Source	Commissioning Task ID
REQ-OCD-0001	Wavelength Coverage	Sky OH emission	IG2-COMM-001
REQ-OCD-0002	Spatial Resolution (Pixel scale)	Double star (SVC)	IG2-COMM-002
REQ-OCD-0003	Field-of-View (slit length)	Double star (SVC)	IG2-COMM-002
REQ-OCD-0004a	Spectral Resolution	Sky OH emission	IG2-COMM-001
REQ-OCD-0004b	Spectral Sampling	Sky OH emission	IG2-COMM-001
REQ-OCD-0005	System Sensitivity	Point Source	IG2-COMM-003
REQ-OCD-0007	Ghost Images	Sky OH emission/Point Source	IG2-COMM-001 IG2-COMM-003
REQ-OCD-0008	Spectral Flattening	Point Source	IG2-COMM-003
REQ-OCD-0009	Wavelength Stability	Sky OH emission	IG2-COMM-004
REQ-OCD-0010b	Slit Viewer Field of View	Double star (SVC)	IG2-COMM-002
REQ-OCD-0010c	Slow guiding	Point Source	IG2-COMM-005
REQ-OCD-0010d	Guiding Error	Point Source	IG2-COMM-005
REQ-OCD-0010e	Slit Viewer Saturation Level	Double star (SVC)	IG2-COMM-002
REQ-OCD-0015a	Total System Throughput	Point Source	IG2-COMM-003
REQ-OCD-0020a	Quasi Real-Time Quick Look	Point Source	IG2-COMM-006
REQ-OCD-0020b	Separate Quick Look Displays	Point Source	IG2-COMM-006
REQ-OCD-0020c	Spectrograph Quick Look Data	Point Source	IG2-COMM-006
REQ-OCD-0020f	Quick Look Spectrum Extraction	Point Source	IG2-COMM-006
REQ-OCD-0020h	Quick Look Processing Time	Point Source	IG2-COMM-006
REQ-FPR-0201	Flexure	Sky OH emission	IG2-COMM-004
REQ-FPR-0202	Tracking Performance	Point Source	IG2-COMM-005

Table 1. List of requirements requiring On-Telescope or On-Sky tests

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Commissioning Task list

Table 2. List of commissioning task IDs and titles derived from requirement

Commissioning Task ID	Title	On Tel/Sky Source
IG2-COMM-001	Sky OH emission	Sky OH emission
IG2-COMM-002	Slit-view Camera	Double star (SVC)
IG2-COMM-003	Point sources Spectra	Point source
IG2-COMM-004	Wavelength Stability	Sky OH emission
IG2-COMM-005	Instrument Guiding	Point source
IG2-COMM-006	Quick Look	Point source

Commissioning Task ID	Title	On Tel/Sky Source
IG2-COMM-007	Detector Checkout	N/A
IG2-COMM-008	Dark and Read noise	Inst. Cover closed
IG2-COMM-009	Telescope Offsets	N/A
IG2-COMM-010	Flats	GCAL Flat
IG2-COMM-011	PWFS-2 Focus Offsets	Point Source
IG2-COMM-012	Cardinal Directions	Point Source
IG2-COMM-013	Instrument Origin	Point Source
IG2-COMM-014	Instrument Alignment Angle	Double Star
IG2-COMM-015	Plate Scale	Double Star
IG2-COMM-016	Blind Offset	Double Star (target + user1)
IG2-COMM-017	Source Acquisition and Nodding	Point Source
IG2-COMM-018	Slit Angle	Double Star
IG2-COMM-019	Facility Guiding	Point Source
IG2-COMM-020	Data reduction	-
IG2-COMM-021	Pupil Alignment	Point Source

Table 3. List of tasks requiring On-Telescope or On-Sky tests that are not covered in Table 1.

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First Light

Scene of the Gemini North control room on first light

Very first light Spectra

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First Light Spectra

2D spectra after initial pipeline process

Planetary Nebula NGC 7027

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Press Release - NOIRLab

IGRINS-2 resolves the dynamic gaseous bubble surrounding NGC 7027, the Jewel Bug Nebula. The bright lines in the rainbow are like the fingerprints of the gasses present in the nebula.

Credit:

International Gemini Observatory/NOIRLab/NSF/AURA/NASA/ESA/J. Kastner (RIT)

Image Processing: M. Zamani (NSF’s NOIRLab)

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First Light Spectra

H- and K-bands first point source spectra (HBC 722)

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First Light

Chan Park

Woojin Park

Now in Yokohama!

Ueejeong Jeong

Charlie Figura

Hyewon Suh

Sanghyuk Kim

Hye-In Lee

Ruben Diaz

Pablo Prado

Hwihyun Kim

Heeyoung Oh

John White

Francisco Ramos

Jen Miller

Emma Kurz

Hawi Stecher

Hyun-Jeong Kim

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Sample spectra: TW Hya

Gemini Focus (July 2018)

Mace et al. SPIE 2018

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Sample spectra: TW Hya

IGRINS @ GS: 64s, S/N=337(H), 330(K), AM 1.02
IGRINS-2 @ GN: 96s, S/N= 418(H), 395(K), AM 1.74

Na I doublet

CO bandhead

*Not for absolute SNR comparison

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Performance Verification

with early result

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Wavelength Coverage

[REQ-OCD-0001] Wavelength Coverage: 1.49-1.80 m (H band) and 1.96-2.46 m (K band)

1.49-1.80 μm

H

K

1.96-2.46 μm

Reduced data with IGRINS pipeline

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Line width measurement - OH emission

FWHM of line is measured in pixel unit over the detector area. (data from Jan. 2024)

H

K

[REQ-OCD-0004a] Spectral Resolution: Spectral resolution 36,000 (<4.07 Pixels) over 90% of each band and 32,000 (4.58 pixels) over 100% of the band

[REQ-OCD-0004b] Spectral Sampling: Spectral Sampling: average line width on the blaze is 3.66 pixels

< 3.5 pixel

<3.2 pixel

No OH lines beyond 2.3 μm

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K-band longer λ orders

Lab data is consistent with on-sky data

Well resolved narrow lines down to

Δv ~7 km/s (spectral resolution)

CO bandhead

(FU Ori type YSO)

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SVC FoV

Diameter of the field = 1,160 pixel
Plate scale of SVC = 0.04 arcsec/pixel
FoV ~ 46 arcsec

Diameter of the unvignetted field:

1,160 pixel

[REQ-OCD-0010b] Rqmt: 40 arcsec +/- 5% diameter

Orion BN field, Jan. 2024

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Sensitivity: Early result

~80 point source observations from test runs are listed and reduced
Peak SNR from pipeline result vs. requirement (and ITC) compared

IGRINS-2 S/N Estimation

Table screenshot (part)

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Sensitivity: Early Result

Rqmt: IGRINS-2 shall be capable of achieving a signal-to-noise ratio (S/N) of 100 in a 3600 s (6 x 600 s) exposure for point sources with H- and K-bands brightness of 13.8 and 13.2 mag, at R=40,000 spectral resolution and at typical wavelengths along the blaze.

Sensitivity requirements

(CC50 / IQ70 conditions) at AM < 1.2

m_HorK	S/N (H)	S/N (K)
m_HorK	8 m	8 m
9
10
11	380	299
12	238	187
13	148	115
14	90	68
15	52	38
16	28	17

In average, sensitivity satisfy the requirement with S/N is ~30% higher than rqmt.

Note: the rqmt assumes IQ 70 while the sky condition was variable during the test
The actual magnitude of the target could be different from that of 2MASS.

Comparison and analysis with ITC output based on as-built data is underway.

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Instrument Flexure

Success Criteria: Spectral spectral shift <1/2 pixel with the change of dewar orientation of 15 degrees.
On-sky test: 300s blank SKY spectra at different position

30, 60, 90 degrees telescope elevation
0, 90, 180, 270 degrees IPA

K band: The maximum line displacement between all position is ~1.2 pix, but when we consider 15 degrees change (=1 hr), the maximum displacement should be <0.2 pixel.

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Ghost Check

Raw images of NGC 7027 with bright emission lines ~4,000 counts (first spectra)

We had some unresolved K-band ghost feature in the lab data

Appeared only in Th-Ar lamp image which has many bright, saturated emission lines
On-sky source with bright emission lines is good test target, ex) NGC 7027
No feature found in NGC 7027 with max ~4,000 counts, also no ghost in point source with high count

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Pupil Image

IGRINS-2

(Ks band slit-view)

Telescope axis (acquisition camera)

IPA 90, M2 = +2000 μm

IPA 180, M2 = -2000 μm

Pupil images showed no signs of tilt in alignment.

(Jan. 2024)

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Upcoming Schedules and Tasks

Detector issues : Noise, Ghost + Additional Maintenance – TBD

Data reduction pipeline

Update with detector noise improvement
Transition to the Gemini DRAGONS version

Normal operation at Gemini North – November (TBD)

November: IGRINS-2 Shared Risk Call for Proposals for the Fast Turnaround
Regular operations in 2025A and beyond

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Thank you!

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Backup slides

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IGRINS Science Example

“A Precise Carbon and Oxygen Abundance Determination in a Hot Jupiter Atmosphere” Line et al. (2021, Nature)

Exoplanet

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IGRINS Science Example

ISM Studies

“Detection of pristine circumstellar material from Cas A” (Koo et al. 2020)

"Discovery of Rubidium, Cadmium, and Germanium Emission Lines Planetary Nebulae” (Sterling et al. 2016)

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IGRINS-2 Echellogram

H

K

Spectral order number and free spectral range is marked on the IGRINS-2 flat images.

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Post-shipment – H

Pre-shipment

Post-shipment

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Post-shipment – K

Pre-shipment

Post-shipment

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	Conversion Gain (mean)		Full Well Capacity		Readout noise
Requirement ▶	N/A		> 60,000 e-		< 20 e- @ CDS		< 7 e- @ Fowler-16
Detector ▼	(e-/ADU)	(ADU)	(e-)	Compliance (O or X)	(e-)	Compliance (O or X)	(e-)	Compliance (O or X)
H	2.5	40,000	100,000	O	14.4	O	5.46	O
K	1.7	52,000	93,600	O	13.3	O	4.83	O

	Dark Current		Bias (reference) variation / hr		Gain variation / hr
Requirement ▶	e-/pix/sec		< read noise		< 1%
Detector ▼	(e-/pix/sec)	Compliance (O or X)	(e-)	Compliance (O or X)	% in CV	Compliance (O or X)
H	0.0225	TBD	0.088	O	0.23	O
K	0.0238	TBD	0.060	O	0.89	O

Summary