2022 Call for Proposals

Issued: 15 March 2022

Deadline for submission of proposals: 3 May 2022, 14:00 SAST (12:00 UTC)

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1 Introduction

The South African Radio Astronomy Observatory (SARAO) through this Call elicits observing proposals for MeerKAT, seeking to maximize the scientific impact of the telescope while contributing to South African scientific leadership and human capital development.

MeerKAT is a radio interferometer located in the Northern Cape province of South Africa (at 30 deg South, 21 deg East) consisting of 64 dishes with baselines of up to 8 km. Its superb sensitivity, ~2000 baselines, centrally concentrated distribution (~3/4 of the dishes are located in a 1 km diameter core), substantial field of view (~1 deg FWHM at 1.4 GHz), and unblocked aperture design, make it uniquely suited to a variety of studies.

Imaging results to date drawing on these capabilities include the detection of low surface brightness neutral hydrogen (e.g., de Blok et al. 2020; Healy et al. 2021), high fidelity imaging of extended Galactic structures (e.g., Heywood et al. 2022), continuum observations exceedingly sensitive to distant star forming galaxies (e.g., Mauch et al. 2020) and diffuse emission in cluster environments (e.g., Chibueze et al. 2021; Knowles et al. 2022), enabling the discovery of unexpected features in radio galaxies (e.g., Ramatsoku et al. 2020), absorption line detections in both L and UHF bands (e.g., Combes et al. 2021), neutral hydrogen intensity mapping studies (e.g., Wang et al. 2021), efficient imaging in snapshot mode (e.g., Condon et al. 2021), broadband spectro-polarimetry across a large FoV (e.g., Cotton et al. 2020), and numerous image-plane time-domain discoveries (e.g., Bright et al. 2020).

This is the third ‘Open Time’ Call for Proposals (CfP) on MeerKAT. It is open to PIs with any affiliation. Compared to previous CfPs, we provide a more streamlined proposal submission process, backed up by updated documentation and tools (e.g., sensitivity calculators), more capabilities are offered (e.g., correlator modes), and there are fewer restrictions on observing time limits, alongside a larger overall amount of time to be awarded.

It is very important that prospective proposers begin preparations early, and that they contact SARAO with any questions well in advance of the deadline for submission on 3 May 2022. Also, it is essential that all instructions related to this CfP be adhered to, as non-compliant proposals will not be reviewed. We also encourage prospective users to familiarize themselves with the general guidelines on MeerKAT telescope and data access.

2 Who Can Submit Proposals

Proposals submitted under this CfP may be led by any researcher (including postdocs and PhD students), regardless of affiliation.

The basic MeerKAT imaging data product consists of interferometric visibilities, at high rates (the 32K correlator mode yields at least 1 TB of data per hour). Also, MeerKAT has some particular characteristics that may require adaptation during processing by researchers only familiar with other radio interferometers. In the preparation of proposals, SARAO therefore encourages collaboration between new users and those who have prior MeerKAT experience.

3 Available Capabilities and Constraints

This CfP is open for imaging projects only. It is expected that at least 1500 hours of telescope time will be available through this CfP, with all approved projects to be scheduled over a period of one year (to start during the last third of 2022, as soon as reviews conclude).

3.1 Time limits

Individual proposals are limited to a maximum request of 125 hours, including calibration and slewing overheads. The maximum time on-source for the science target(s) is 100 hours.

3.2 Bands/receivers

  • UHF: digitized band of 544–1088 MHz (RF band of approximately 580–1015 MHz);

  • L band: digitized band of 856–1712 MHz (RF band of approximately 900–1670 MHz).

Both bands are suitable for full-Stokes polarimetric work (although there are limitations for wide-field polarimetry as noted in the documentation); and individual proposals can request the use of multiple bands (note that in some tools UHF is referred to as U-band).

3.3 Correlator modes

  • 4K: 4096 channels across the digitized band;

  • 32K wide: 32,768 channels across the digitized band;

  • 32K narrow (also known as NE107): 32,768 channels across 1/8 of the digitized band (107 MHz at L band; this mode is not yet available with the UHF band).

The NE54 mode (twice the frequency resolution of NE107) is available in shared risk mode at L band. Users interested in this capability should contact SARAO to discuss possible use cases, rather than submitting a proposal in response to this CfP.

3.4 Target-of-Opportunity requests

ToO requests are for transient targets/events that could reasonably be predicted to occur within the observing span associated with the current CfP, i.e., that could be triggered within a 1 year period expiring by October 2023. Rare enough events for which reasonable prediction of rates cannot be supported should be proposed under Director’s Discretionary Time. Furthermore, a compelling ToO proposal addresses a narrow object class with well-defined science goals.

3.5 Non-standard modes

Some capabilities that prospective MeerKAT users may be familiar with using at other telescopes may not yet be available on MeerKAT (e.g., OTF mapping, particular noise-diode firing schemes, solar observations), or may have MeerKAT-specific implementations that could impact the attainment of some science goals.

Users considering potentially non-standard observing modes must discuss their plans with SARAO well in advance of the submission deadline to evaluate suitability for the current CfP. In case of doubt, please contact SARAO.

3.6 Data products

The official imaging data products provided by SARAO to MeerKAT users consist of visibilities with basic flagging, calibration solutions and reports.

Continuum and spectral image cubes are also automatically generated by the Science Data Processor (SDP) pipeline for some observations. These are primarily generated for quality assessment purposes but have already been shown to be useful for some science investigations. Proposers are encouraged to learn about the power and limitations of SDP pipeline products, and as relevant consider the feasibility of using these for specific science applications.

In any case, proposals submitted under this CfP must address the feasibility of achieving their science goals on the basis of analyzing the relevant data products (which for most current MeerKAT imaging projects are the visibilities).

3.7 Documentation on MeerKAT capabilities

Prospective proposers are directed to documentation on telescope capabilities and constraints on the External Service Desk Knowledge Base. Any questions should be addressed to SARAO well in advance of the submission deadline.

4 Determining Targets for Observation and Time Requests

MeerKAT observing projects are approved to address specific science goals, alongside the targets/fields and integration time/modes required to achieve those scientific objectives. Newly proposed projects may not unduly clash with the specific science goals of ongoing large projects.

Note that it is entirely possible to have multiple projects observing some of the same targets, to address different science goals. For instance, a project with a large sample of targets selected according to well-defined criteria may happen to observe one galaxy that is the specific focus of a separate project with distinct aims observing the same galaxy with a different integration time and/or using different telescope modes.

In order to not clash with active large projects, prospective proposers should become at least passingly familiar with those projects (LSPs, active SARAO Legacy Surveys, and the MPIfR L-band survey).

4.1 Approved projects and existing datasets

All approved MeerKAT Large Survey Projects (LSPs), Open Time (OT), and Director’s Discretionary Time (DDT) projects are listed here.

The projects dashboard provides a view of all science observations done to date. Also, the data archive search interface (which includes functionality such as a cone search) can be used to list useful information about all science observations done with MeerKAT (e.g., integration times and receiver/correlator modes, and whether those data are publicly available).

Note that the data collected for many projects are already public, and some projects have issued curated data releases which may be used for further science exploitation.

Other substantial current projects include: SARAO Legacy Surveys of the Galactic plane and of the Magellanic Clouds (all done at L band with the 4K mode of the correlator); some other SARAO Science Verification (SSV) datasets; and an MPIfR-led L-band Galactic plane survey. Prospective proposers are encouraged to learn more about these projects.

Any questions regarding the status of existing MeerKAT datasets and how they might relate to the submission of new proposals can be addressed to SARAO in advance of the submission deadline.

4.2 Time requests

The type and number of targets/fields requested in a proposal, along with the observing mode, must be suitably addressed in the context of the science case.

In addition, all time requests must be justified by appropriately motivated sensitivity calculations. To assist, a variety of sensitivity calculators are available.

5 Components of Proposal

All complete proposals consist of 3 mandatory sections (cover sheets; scientific & technical justification; data analysis/management plan). Information on these components follows in the remainder of this section.

5.1 Cover sheets

These are to be completed directly through the proposal submission system, which contains instructions. Both attachments noted in the following sections are also submitted through the proposal submission system.

The cover sheets include fields for information such as proposal title and abstract, broad proposal scientific category (to assist with review), team details, telescope modes, source lists, and overall time requested. Tools are available to assist with the completion of some of these items (e.g., sensitivity calculators; observing run simulation tools, including selection of suitable calibrators and estimated slew time).

5.1.1 Proposal for PhD thesis?

If the proposed project is to form a core component for the PhD thesis of a listed PI/co-PI, this should be indicated under Team Details. Otherwise, this field should be answered No.

If any key member of the current proposal team (including, but not limited to, the PI and technical lead) has been a key member of any previous MeerKAT Open Time or DDT project that is closely related to the new proposed project, a brief status update must be included for up to the 3 most relevant projects.

If the project has already resulted in any publication, provide paper title(s) and standard bibliographic information; optionally, also add a sentence about the contents of the paper(s). If paper(s) have been submitted or are in advanced states of preparation, indicate so and outline the main results (and any technical issues if relevant). Otherwise, indicate the current status, and as relevant any issues – especially as they might connect to the current proposal (e.g., data analysis).

5.2 Science case: scientific justification & technical justification

This section consists of one pdf document (maximum size 10 MB), with a limit of three (3) pages using font size no smaller than 11 pt and with standard margins. An abstract, and relevant figures/tables and references must be included within this page limit.

There can be no explicit identification of team members within this document, as it will be reviewed in dual-anonymous fashion. In addition, refrain from style that indirectly identifies teams – e.g., instead of ‘As we have shown in Author et al. (2021)’, write rather ‘As shown by Author et al. (2021)’.

This is the only section that may contain the scientific and technical justification for the proposal, in a self-contained fashion (the scientific reviewers will not have access to the cover sheets including the abstract therein, or any other section of the proposal). The following considerations apply:

i. This document should be written for an astronomer who is not an expert in the sub-field (e.g., it may be assumed that the reviewer has expertise in some continuum science if they are reviewing such a proposal, but particular expertise should not be assumed on, say, galaxy clusters or star forming galaxies).

ii. The scientific justification portion should provide context for the science goal(s) being proposed, and it should be explicit (no generalities) as to what it aims to achieve science-wise, and also how the proposed observations, if successful, will do so. Why are these interesting questions to address, and how does the proposed work advance on the current state of the art? Previous relevant work on the topic, regardless of telescope used, should be noted. If MeerKAT is the most suited instrument available for this investigation, indicate how.

iii. The technical justification portion should make a clear connection between the specific science goals to be achieved and the observing request (e.g., flux density or flux density per synthesized beam solid angle limits, target(s), areal coverage, number of visits – which in turn quantitatively drive the overall requested time). The RFI environment should be taken into consideration as relevant. Also, any requested integration period of less than 8 seconds or night-time observations must be justified.

This section should also succinctly note the time(s) requested on-source for the science target(s) as well as overall request including overheads, band(s)/mode(s) to be used, and identity of source(s)/field(s) to be observed. For large source lists, only the criteria need to be indicated here. If the default overhead fraction of 25% is not selected in the cover sheets, this section must note the expected fraction, backed up by Observation Planning Tool simulations.

As relevant, note additional requirements (e.g., dynamic range) and discuss possible constraints (for instance, bright sources in the field, and how they’ll be dealt with – e.g., by addressing direction-dependent effects – if they might otherwise impact attainment of the science goals).

As noted in Section 3.4, Target-of-Opportunity requests must be narrowly tailored. Apart from addressing the specific science goals, proposals with ToO classification have to address in this section predicted event rates (reasonably expected to be triggered within a 1 year period), provide a sense of their brightness, and the triggering criteria, including what facilities will generate them. 

5.3 Data analysis/management plan

This section consists of a 1-page pdf document.

Turning large amounts of MeerKAT data into science can be challenging. A proposal with a compelling science case but an unrealistic or unclear data analysis management plan is unlikely to be ranked highly overall.

In this section the proposers should outline their intended analysis plan and indicate the resources that they have at their disposal for the relevant tasks. These resources include:

i. Personnel with the necessary expertise. The role of identified key team members, whether technical or scientific, should be outlined, and relevant experience with MeerKAT data analysis if any should be noted.

ii. Software. The status of any relevant software (e.g., pipelines still under development) should be indicated.

iii. Hardware. It’s important to note whether access to the required tools and computing resources has been secured. This will also have been outlined in the cover sheets.

In this context (especially for larger/more challenging projects), it may not be sufficient to state that the data will be processed at ‘X institute’; rather, the proposers should seek to make quantitative estimates of their storage and compute requirements, and indicate either that they already have access to those specifically required resources, or outline how they reasonably intend to acquire them.

6 Review of Proposals

All valid proposals received under this CfP will be evaluated on the merits of their science case and feasibility. In addition, proposals that form a core component for the PhD thesis of South African-based students, or that build South African capacity for Key Science with SKA1, will be advantaged compared to otherwise similarly meritorious proposals.

First, different sections of proposals will be reviewed in a non-conflicted manner as follows:

i. The full science case (Section 5.2) will be reviewed by anonymous domain experts in dual-anonymous fashion (i.e., the reviewers will not have explicit knowledge of the identity of the proposing teams), according to guidelines provided by SARAO.

ii. The technical justification of the science case, data analysis/management plan (Section 5.3), and if relevant status of previous closely related projects (Section 5.1.2), will be reviewed by SARAO, with input from external experts as needed.

These reviews will inform the assessment of the overall feasibility of the proposed project.

A Review Panel appointed by the SARAO Managing Director will then incorporate the above inputs and recommend to the MD a rank-ordered list of proposals suitable for scheduling on MeerKAT, together with other recommendations as relevant (e.g., partial time allocations).

After taking into account any other relevant constraints (e.g., pressure for particular LSTs or day/night-time observing), SARAO will group proposals into three classes: A (will be observed); B (may be observed); C (will not be observed). Following this, all PIs will receive feedback on the disposition of the proposals.

Suitable sections of the cover sheets of approved projects may be made public.

7 Timelines

This CfP is being issued on 15 March 2022.

All documentation and tools required to prepare proposals in response to the CfP are available as of this date.

Proposals may be submitted on the submission system until 12:00 UTC on 3 May 2022.

Successful proposals will start being scheduled on MeerKAT as soon as the review process is completed and communication on outcomes is provided to PIs. This is expected to happen in the last third of 2022.

8 Proprietary Periods

By default, the data associated with any project approved under this CfP will have a proprietary period of 12 months, counting from the date of last data collection for the project. After the proprietary period expires, the visibilities, and data cubes produced automatically by the SDP pipeline if any, will become freely available through the MeerKAT data archive interface.

Approved projects that form a significant component of the thesis work of PhD students may be considered by SARAO for proprietary periods of up to 18 months.

Note that currently SARAO does not guarantee the storage of either visibility data or any associated image cubes substantially beyond the proprietary period of the observations. Teams may wish to arrange their own storage should they see longer term value in retaining the data.

9 Publications and Acknowledgements

We request that authors inform SARAO of refereed papers accepted for publication, or theses, that include MeerKAT data. These will be added to the MeerKAT ADS Library.

Such publications should contain the following acknowledgement statement:

The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation.

10 Contact Information

Any questions pertaining to the current MeerKAT Call for Proposals should be addressed to SARAO as soon as possible in advance of proposal preparation/submission by raising a ticket on the SARAO External Service Desk. Feedback on the documentation and tools associated with this CfP is also welcome.