MeerKAT Extension (MK+) Overview

1 Feb 2023

MeerKAT capabilities over time

• 2016: First Light (16 antennas); L-band; ROACH2 correlator
• 2018: 64 antennas; L-band; SKARAB correlator (4k imaging mode)
• 2019: Beamformed pulsar timing mode (PTUSE); 32k-wide imaging mode
• 2020: UHF band; pulsar/transient search mode (FBFUSE/APSUSE/TUSE); 32k-narrow (NE107) imaging mode
• 2021: NE54 32k-narrow imaging mode; 4 steerable beams
• 2022: S-band; BLUSE commensal mode
• Next: MeerKAT Extension…

The MeerKAT Extension (MK+) project

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• Started in 2019 as a joint SARAO/MPIfR project
• INAF joined in 2020
• Goal: to develop exciting novel capabilities for MeerKAT, in the context of eventual contributions to SKA-Mid
• Enormous project, drawing on significant resources in: systems engineering, infrastructure, dish structures, receivers, vacuum/cryogenics, fiber optic networks, digitizers, correlator, science data processor, control and monitoring, commissioning…

The future today: MK+ underway

Capabilities and project plan

MK+ capability summary

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• 13-16 new antennas, of ‘SKA design’ (each ~1.35x more sensitive than MeerKAT’s)
• Maximum baselines ~17 km (~twice as much as MeerKAT)
• Populated with L- and S-band receivers (not UHF)� ‘L’ are SKA Band-2 receivers (0.95–1.76 GHz, compared to 0.9–1.67 GHz for MeerKAT L)� Only half of the S band (1.75–3.5 GHz) processed at once
• Backend to process all 80 antennas simultaneously
• New independent GPU-based correlator for all 80
• Initial wideband correlator mode: 8k channels
• Upgraded SDP to ingest and store visibilities of this mode
• Current SKARAB-based (any) 64-antenna correlator with USE will remain fully functional

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Updated array configuration (TBC)

(One representative option; 20 foundations already built)

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System capability and phasing

Current MeerKAT capabilities�Beam, Visibilities 4k, 32k, 32k Narrowband, Calibration, Phase-up, Imaging, USE, Commensal

Capabilities on any 64 antennas�[with some limits]: Beam, Visibilities 4k, 32k, 32k Narrowband, USE, Commensal

Capabilities on all 80 antennas�Single new 8k mode: Visibilities

MK

MK+

Phase 2

~end 2024?

Now

Additional features

MK+

Phase 1

2025+

System design

64 antennas

CBF

SDP

64 antennas

CBF

SDP

16 antennas

64 antennas

CBF

Upgraded SDP

16 antennas

split

NewCBF

MK

MK+

Phase 1

MK+ Phase 2

Phase 1: ‘Any 64’ mode

Current SKARAB correlator is compatible with new antennas

New antennas will be connected to existing switch at first

Subarrays (4) can be built using any combination of new and old antennas

Visibilities recording will work normally on up to 64 antennas

However:

• Longer baselines will require a dump rate faster than 8 sec (4 s, maybe 2 s)
• Existing SDP maximum dump rate is 2 s
• Real-time imaging may not work (longer baselines and heterogeneous array)

Phase 2: ‘All-80’ mode

New correlator will process all 80 antennas

Why ‘only’ 8k at first?

• Driven by scale of SDP
• Ingest bandwidth and CPU
• Storage constraints
• Visibility storage data rate comparable to MeerKAT 32k (~2 TB/hr @ 8s, full Stokes)
• MK+ 8k @ 4s (2s) is ~ 0.8 (1.6) x MK 32k @ 8s
• Data reduction/imaging for science will be very challenging

All original MeerKAT modes still available at this phase, with 64 antennas

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Operational model

Current MeerKAT-64 backends and antennas

• Science program continues

MK+ Phase 1: Any 64

• Antennas planned to arrive in 2024
• Testing (e.g., holography)/commissioning to start when needed subsystems in place
• Once commissioning done, suitable small science projects may start

MK+ Phase 2: All 80

• Still unclear when All-80 (8k correlator mode) imaging science may start (project plan being updated)

Towards a MK+ science program

MeerKAT Extension: preparing for science

• MeerKAT extension represents a major new capability for MeerKAT
• 0) Early Science opportunities for team doing commissioning
• 1) Majority of new telescope time to be awarded through Open Time Calls
• 2) ~10% reserved share to be used by project partners (SARAO/MPIfR/INAF) to generate a MK+ Legacy Science Program
• White Paper with three ideas produced in 2021

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• Community engagement: Nov 2022 webinar; Feb 2023 science workshop

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• Preparing for science
• What science could be done with MK+ that can’t (easily) be done with MeerKAT?
• Some pilot/related work can/should be done with current MeerKAT
• It’s hard enough for MeerKAT visibilities to be turned into science; it’ll be substantially harder for MK+ – it’s crucial to address this alongside science ideas

Science use of enhanced MeerKAT by MK+ partnership

• Intent of joint collaboration is to select observing project(s) for reserved share that produce legacy science products remaining relevant into SKA era
• For planning purposes, reserved share is ~500 hr/yr, until integration into SKA-Mid
• Current White Paper (WP) presents ideas for 3 legacy science projects
• Two at L-, one at S-band; each would require more telescope time than may be available at this point, but are inherently scalable to different degrees
• Projects outlined in WP are starting point for further development/eventual downselection of collaborative science program; other projects could be considered/developed by community
• At a suitable time, proposals seeking to utilize reserved share will be evaluated based on scientific and technical merit by a review panel
• Selected project(s) will be different from PI-led projects in being inherently open to research communities of all MK+ partners (data to be ‘owned’ by partners, not PIs)
• After downselect, discussions with relevant research communities, to establish and implement end-to-end requirements for broad science exploitation of expected datasets

Next steps towards the MK+ Legacy Science Program

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• The relevant science communities should engage amongst themselves, with each other, and as relevant with SARAO staff developing backend
• Suitably assessing feasibility of proposed projects will require evaluation of science and technical risk – which can be minimized/retired through pilot projects
• It can be assumed that by early 2025 the extended MeerKAT will have substantial novel capabilities to be exploited for science – however, it should not be assumed that it will immediately have specific capabilities defined now for particular goals. Planning for science projects should be resilient against these uncertainties

2023 MK+ Science Workshop

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• 1-3 Feb 2023 at Wits Rural Facility
• Aims: preparation for MeerKAT+ science, including a focus on survey design and team coordination for the SARAO/MPG/INAF Legacy Programme
• Details at wits-astro.org/mkplus2023
• Queries: mkplus2023@gmail.com

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