Issued: 1 June 2024

Deadline for submission of proposals: 15 July 2024, 14:00 SAST (12:00 UTC)

A printable pdf version of this document can be accessed here.

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 (HCD).

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 have included the detection of low surface brightness neutral hydrogen (e.g., Serra et al. 2023; de Blok et al. 2024), 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., 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., Cunnington et al. 2023), 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).

MeerKAT also has a variety of non-imaging capabilities enabled by User Supplied Equipment (USE). Science projects drawing on these beamformed capabilities encompass high-precision pulsar timing (e.g., Miles et al. 2023), accelerated pulsar searching (e.g., Clark et al. 2023), and real-time detection of transients (e.g., Rajwade et al. 2022).

This is the 5th ‘Open Time’ Call for Proposals (CfP) on MeerKAT (also referred to as OT5; it is planned that future CfPs will be issued yearly). It is open to PIs with any affiliation. Compared to the OT4 CfP, we offer a new proposal type (for extra-large projects), and have updated some other constraints (e.g., related to proposals using S-band receivers, and multi-year proposals). The documentation and tools have also been updated accordingly. Future MeerKAT capabilities to be available through the MeerKAT Extension project (MeerKAT+) are not relevant for this CfP.

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 15 July 2024. Also, it is essential that all instructions related to this CfP be adhered to, as non-compliant proposals will not be reviewed. Prospective users may also wish to familiarize themselves with the general guidelines on MeerKAT telescope and data access.

2 Who Can Submit Proposals

Proposals submitted in response to 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 data reduction by researchers only familiar with other 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 and non-imaging (beamformed) projects alike. It is expected that at least 3000 hours of telescope time will be available through this CfP. This refers to the amount of time to be scheduled for approved OT5 projects over a 12-month period (to start in late 2024, as soon as reviews conclude).

3.1 Proposal types and time limits

• Regular

Individual Regular proposals are limited to a maximum request of 100 hours over the entire duration of the project, including calibration and slewing overheads. Given an assumed overhead of 25%, the maximum time on-source for the science target(s) is 80 hours.

• Large

Any proposal that requests more than 100 and up to 300 hours overall, including overheads.

• Extra large

Any proposal that requests more than 300 hours overall, including overheads. The maximum time request for an eXtra-Large Proposal (XLP) is 2200 hours. 

• Multi year

Some projects (whether Regular, Large, or XLP) may also be Multi-year. 

Projects may be submitted through this CfP that must or may have to be scheduled over more than 12 months. Such Multi-year proposals will have to indicate and justify their overall time request as well as the request for the immediate 12 months covered by this CfP cycle. For planning purposes, during OT5 a Multi-year proposal can consider a time horizon of up to 4 years. Important constraints related to this topic are noted in Section 3.1.3 below.

Any proposal that requires observations over more than 12 months for scientific reasons (e.g., some monitoring projects) is of Multi-year type. In addition, any XLP that requests more than 500 hours is also Multi-year because of scheduling constraints: individual successful OT5 proposals will be limited at most to 500 hours in the immediate 12-month observing cycle covered by this CfP.

For example, a monitoring project that requests 10 hours per year over 3 years is a Regular, Multi-year project; a monitoring project that requests 40 hours per year over 3 years exceeds 100 hours and is therefore both Large and Multi-year; a project that requests 350 hours is an XLP but need not, inherently, be Multi-year (if it could be scheduled within a 12-month period); while any project that requests more than 500 hours in total is a Multi-year XLP.

3.1.1 Large proposals and pilot studies

Successful Large proposals will have to be exceptionally well motivated in all respects. This includes the clear demonstration of their feasibility. As noted in the MeerKAT telescope use guidelines, Large projects “have to first demonstrate technical and/or scientific feasibility through the successful completion of smaller pilot studies. Depending on the details, such projects might be deemed to have already demonstrated readiness by comparison to prior successful suitably analogous projects”.

In the context of the current CfP, Large proposals must clearly demonstrate that the above requirement has been met. If not, the authors should rather consider submitting a Regular proposal that may be a pilot for a future Large proposal.

3.1.2 XLPs and response to Expressions of Interest survey

As for Large proposals, successful XLPs will have to be exceptionally well motivated in all respects. In addition, XLPs will have to demonstrate that they are ready to reduce and analyse their data at scale from day 1. That is, XLP proposals will have to show that the required teams, hardware, software, pipelines, etc, are in place and demonstrably ready for the intended data throughput and science goals of the proposal. In effect this likely means that successful XLPs will have started as successful very closely related prior (or currently active) MeerKAT projects. Large Survey Projects (LSPs) that will remain active as of the start of scheduling successful OT5 proposals (estimated in late 2024) are not eligible to submit XLPs for OT5.

In order to assist with the management and review of XLPs during OT5, SARAO required that prospective XLP PIs respond to a survey with a deadline of May 2, 2024. Only those that did so are eligible to submit XLPs for OT5. 

Authors of would-be proposals that do not currently qualify to be submitted as an XLP may rather consider submitting another proposal that could in future form the basis for an XLP.

3.1.3 Multi-year proposals and future CfP cycles

MeerKAT will be integrated into the SKA-Mid telescope, now under construction. The timelines for this will be milestone dependent and are subject to considerable uncertainty. However, it is possible that MeerKAT will no longer be available as a standalone instrument by ‘Year 4’ in the context of Multi-year proposals under the current CfP (i.e., for telescope time to be scheduled from late 2027). This imposes constraints on what telescope time SARAO will currently award for future years.

In addition, SARAO wishes to retain flexibility to consider potentially exciting and entirely new substantial requests for telescope time in future CfPs. This implies that not too much time for future years should be pre-allocated on the basis of OT5 Multi-year proposals.

Considering the above constraints, a substantial but capped amount of ‘Year 2’ telescope time is expected to be conditionally pre-allocated during the current review cycle for some exceptional OT5 Multi-year proposals. All other projects that wish to obtain time for Year 2, and all projects wishing to continue thereafter, will need to (re)submit proposals that will be evaluated against all proposals received in response to future CfPs.

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)

• S band: any of 5 sub-bands (S0–S4), each digitizing an 875 MHz-wide band, can be selected within the 1750–3500 MHz range

L band and UHF are suitable for full-Stokes polarimetric work (although there are limitations for wide-field polarimetry as noted in the documentation).

 The newer S-band capability is offered in shared-risk mode. The time limit for proposals requesting it is increased with respect to that during OT4: up to 100 hours (including overheads) of S-band time can be requested for proposals submitted during the OT5 cycle (this is inclusive of any possible Multi-year requests).

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, USE backends, and sub-arrays

3.3.1 Correlator modes for imaging observations

• 4K: 4096 channels across the digitized band

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

• 32K narrow: 32,768 channels across 1/8 (107 MHz; NE107) or 1/16 (54 MHz; NE54)  of the digitized band (these modes are available only for L band)

3.3.2 USE for beamformed observations

The following User Supplied Equipment backends are available for a variety of beamformed time-domain applications:

• PTUSE: Pulsar Timing USE (for pulsar timing and searching with up to 4 steerable beams)

• FBFUSE: Filterbanking Beamformer USE (generating up to hundreds of independently steerable beams)

• APSUSE: Accelerated Pulsar Search USE (to record, and in limited circumstances do off-line processing of, multi-channel fast-sampled time series produced by FBFUSE)

• TUSE: Transient USE (for real-time searching/studies of transients, alongside FBFUSE)

These backends have many options (e.g., number of beams, channelization, sample times) and constraints that must be understood first by consulting the relevant USE technical documentation. Then, any team contemplating submitting a proposal using any of these backends must consult with the relevant contact point(s) indicated in the documentation for a technical evaluation. In addition, any proposal requesting any USE backend must contain at least one experienced user of the relevant backend(s) who also has the ability to access the collected data.

Additionally, APSUSE availability for projects selected through this CfP is limited, owing to its need for ongoing large projects. In the aggregate, approved projects requesting APSUSE will be limited to recording data from no more than 100 hours of observations during the immediate 12-month cycle covered by this CfP.

Note also that the TUSE backend is used in commensal mode alongside most MeerKAT observing projects. Unless a proposal explicitly requests the use of TUSE for its key science goals, or justifies why its use by others in commensal mode would clash with core science goals and should be excluded, such commensal use will generally proceed by default.

3.3.3 Sub-arrays

Most MeerKAT projects use as many of the 64 antennas as are available to observe one target at one band at a given time. However, it is also possible to create up to 3 simultaneous ‘sub-arrays’ whereby one target can be observed at multiple bands by using a portion of the antennas for each band; or multiple targets (e.g., bright pulsars) can be observed at one band by using a portion of the antennas for each target. Details are provided in the on-line documentation.

3.4 Target-of-Opportunity requests

ToO requests are for transient targets/events that could reasonably be predicted to occur within the immediate observing span associated with the current CfP, i.e., that could be triggered within a 1 year period expiring by November 2025. Any request for a Multi-year ToO project must be exceptionally well justified, and directly connected to reliable event rates. 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 Proposals connected to ongoing MeerKAT LSPs

As of this CfP, 6 of the 8 original MeerKAT Large Survey Projects (LSPs) are ongoing. In general, proposals that could be considered an extension of ongoing LSPs will not be accepted through this CfP. Any potential exceptions must be discussed with and approved by SARAO well in advance of the submission deadline. It is also recommended that any other proposals that may be closely linked to ongoing LSPs be first discussed with SARAO.

3.6 Non-standard modes

Some capabilities that prospective MeerKAT users may be familiar with from other telescopes may not currently be available on MeerKAT (e.g., 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 or those not yet commissioned for regular use 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.

3.7 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 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. Beamformed projects, as noted in Section 3.3.2, must in addition demonstrate that their team has the expertise required to collect the data.

3.8 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 unduly clash with active large projects, prospective proposers should become at least passingly familiar with them (see Section 4.1).

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 (and in some cases approved) 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.

Apart from LSPs, substantial active large projects include: a SARAO Legacy Survey of the Large Magellanic Cloud (done at L band with the 4K mode of the correlator); some other SARAO Science Verification (SSV) datasets; and MPIfR-led Galactic plane surveys. Prospective interested 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(s), must be suitably addressed in the context of the Science Case.

Other than through suitable ToO requests (Section 3.4), all individual observing requests must be for already known objects (i.e., a proposal cannot request telescope time to study specific objects whose existence has not yet been established).

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

Section 5.1 addresses the components of Regular and Large proposals. OT4 proposers will be familiar with much of the description, although there are some modifications introduced for OT5. Extra-large proposals (XLPs) have some substantially different requirements, and are addressed in Section 5.2.

5.1 Regular and Large proposals

All Regular and Large proposals consist of three (3) mandatory sections (cover sheets; Science Case containing scientific & technical justification; data analysis/management plan). Important information on these components follows in the remainder of this subsection.

5.1.1 Cover sheets

These are to be completed directly through the proposal submission system, which contains instructions. Both pdf 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 SARAO with reviews), team details, telescope modes, source lists, and overall time requested. All Multi-year proposals must also indicate the number of years (up to 4) that their current plans are based on, and the time requested for the immediate 12-month period covered by this CfP. 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).

i. 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.

ii. Pilot results for Large projects

As noted in Section 3.1.1, a Large project must first have retired technical and/or scientific risk via prior pilot studies/results. This must be indicated in the body of the proposal and a summary must be included in the cover sheets.

iii. Integration times: per target, and overall

The cover sheets require an indication of requested integration time per target, exclusive of overheads, as well as overall proposal time request including overheads. (Time allocations are based on requested time on target, and overall proposal time is an estimate, to be refined for successful proposals on submission of schedule blocks.) In addition, all Multi-year proposals require an indication of the time request for the immediate 12-month cycle covered by this CfP, and overall.

5.1.2 Science Case: scientific justification & technical justification

This section consists of one pdf document (maximum size 10 MB) using font size no smaller than 11 pt and with standard margins. Any abstract, relevant figures/tables, and references must be included within its page limit. The page limit for the Science Case is:

• Three (3) pages for Regular proposals

• Four (4) pages for Large proposals

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. (2023)’, write rather ‘As shown by Author et al. (2023)’, or better yet ‘As shown in [Ref. #]’. Note that anonymization does not preclude teams from incorporating their prior work in proposals where relevant, it rather requires careful attention to how this is done.

This is the only section that may contain the scientific and technical justification for the proposal, in a self-contained fashion – it is the only section that the science reviewers will be asked to consider (e.g., they are not asked to review the cover sheets and their abstract). 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. Also indicate and justify why you’re proposing to do this work on MeerKAT: e.g., is it the most suited instrument available for this investigation?

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 for imaging projects 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)/USE backend(s) to be used, and identity of the source(s)/field(s) to be observed. For large source lists, only the criteria need to be indicated here. Calibration plans should be outlined as relevant. If the default overhead fraction of 25% is not selected in the cover sheets (and it shouldn’t be, if the expected overhead is significantly different), this section must note the expected fraction, with justification (e.g., 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).

For Multi-year proposals, time requests should be clearly stated and justified for both the overall project and the immediate 12-month cycle covered by this CfP. For Large projects, relevant findings from prior pilot studies must be incorporated into the proposal; also, due consideration must be given to the matter of scalability (what would be the impact on science return if substantially less than the full time request could be awarded).

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. 

5.1.3 Data analysis/management plan

This (non-anonymized) section consists of a 1-page pdf document. It will not be shared with the science reviewers, but will be used to help assess the feasibility of the proposed project. 

Turning large amounts of MeerKAT data into science can be challenging. A proposal with a compelling Science Case but an unclear or unrealistic 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:

a) Personnel with the necessary expertise and availability. The role of named key team members, both technical and scientific, must be outlined, and relevant experience with MeerKAT data analysis if any (and data collection/access for any requested USE) must be noted. Other team members need not be noted here.

b) Software. The data reduction and analysis plan must be outlined in sufficient detail to provide confidence that the required outcomes can be achieved. The implications of any software (e.g., pipelines) still under development must be addressed.

c) Hardware. It’s important to note whether access to the required tools and computing resources has been secured (and if not to indicate a timely plan to do so). This will also have been indicated 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 in short order.

Note that the contents of this section of the proposal (addressing in detail how data will be turned into science) are distinct from what needs to be included in the technical justification section of the Science Case (Section 5.1.2), and they will be reviewed differently (Section 6).

As noted in Section 3.1.1, Large proposals will have to be exceptionally well motivated in all respects. This includes the clear demonstration of their readiness to deliver the proposed science at scale. Is it critical that this be comprehensively addressed in the data analysis/management plan section of the proposal.

5.2 Extra-large proposals (XLPs)

All XLPs consist of two (2) mandatory sections (cover sheets; body of the proposal/Science Case including scientific & technical justification, previous observations/results as relevant, data management/analysis/release plan, HCD plan). Important information on these components follows in the remainder of this subsection.

5.2.1 Cover sheets

These are to be completed directly through the proposal submission system, which contains instructions. The pdf attachment noted in the following section is 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 SARAO with reviews), team details, telescope modes, source lists, and overall time requested. All Multi-year proposals must also indicate the number of years (up to 4) that their current plans are based on, and the time requested for the immediate 12-month period covered by this CfP. 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).

i. Proposal for PhD thesis?

In general, it is expected that in addition to papers and Data Releases, XLPs will result in PhD theses. 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.

ii. XLPs, response to Expressions of Interest survey, and prior projects

As noted in Section 3.1.2, an XLP project PI must first have indicated their intent by responding to a SARAO expressions of interest survey, and this must be confirmed in the cover sheets. The proposal also has to demonstrate that the team is ready to reduce and analyze their data at scale from day 1. This must be justified in the body of the proposal. Typically, XLPs will have started as successful related prior (or currently active) MeerKAT projects of suitable scale, in which case the corresponding project code and title must be indicated in the cover sheets; for continuing projects only, the amount of previously allocated time must also be indicated in the cover sheets.

iii. Integration times: per target, and overall

The cover sheets require an indication of the requested integration time per target, exclusive of overheads, as well as the overall proposal time request including overheads. (Time allocations are based on requested time on target, and overall proposal time is an estimate, to be refined for successful proposals on submission of schedule blocks.) In addition, all Multi-year proposals require an indication of the time request for the immediate 12-month cycle covered by this CfP, and overall.

5.2.2 Science Case

This section, the body of the proposal, consists of one pdf document (maximum size 10 MB) using font size no smaller than 11 pt and with standard margins. All contents noted below, as well as any abstract, relevant figures/tables, and references must be included within its page limit. The limit for the body/Science Case of XLPs is eight (8) pages.

Unlike Regular and Large proposals, XLPs are not anonymized – any relevant information about team members and their prior work must be explicitly indicated in the proposal.

This section must contain the scientific justification, technical justification, data analysis/management/release plan, and HCD plan for the proposal, in self-contained fashion – it is the only section that reviewers will be asked to consider (i.e., they are not asked to review the cover sheets and their abstract). 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 pulsar science if they are reviewing such a proposal, but particular expertise should not be assumed on, say, high-precision pulsar timing).

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. Also indicate and justify why you’re proposing to do this work on MeerKAT: e.g., is it the most suited instrument available for this investigation? XLPs should also be placed in the context of other relevant ongoing/planned large projects at other telescopes.

iii. Previous relevant results must be incorporated into the proposal, both for scientific context and to help demonstrate the readiness of the team to produce the proposed scientific outcomes. For proposals that are adaptations/extensions of prior large projects, only relevant components of those projects should be considered; for proposals that are continuations of ongoing projects, their status to date must be addressed. Publications to date from the ongoing projects or relevant ones from the prior projects should be noted.

iv. 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 for imaging projects 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)/USE backend(s) to be used, and identity of the source(s)/field(s) to be observed. For large source lists, only the criteria need to be indicated here. Calibration plans should be outlined as relevant. If the default overhead fraction of 25% is not selected in the cover sheets (and it shouldn’t be, if the expected overhead is significantly different), this section must note the expected fraction, with justification (e.g., 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).

For Multi-year proposals, time requests should be clearly stated and justified for both the overall project and the immediate 12-month cycle covered by this CfP. Due consideration must be given to the matter of scalability (what would be the impact on science return if substantially less than the full time request could be awarded).

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.

v. Data analysis/management/release plan. As noted in Section 3.1.2, XLPs will have to be exceptionally well motivated in all respects. In particular, they must demonstrate that the team is ready to reduce and analyze their data at scale from day 1. That is, XLPs will have to show that the required teams, hardware, software, pipelines, etc, are in place and demonstrably ready for the intended data throughput and all science goals of the proposal.

An XLP that cannot demonstrate the above will not be selected, regardless of its other strengths.

If the above cannot be demonstrated with a high degree of confidence, the authors should rather consider submitting a Regular or Large proposal that may be a pilot for a future XLP.

The proposal must contain in suitable detail the intended data analysis plan and indicate the resources at the disposal of the team for the relevant tasks, which must match the needs. These resources include:

a) Personnel with the necessary expertise and availability. The role of named key team members, both technical and scientific, must be outlined, and relevant experience with MeerKAT data analysis (and data collection/access for any requested USE) must be noted. The key team members must be available as required for this project, without undue impact to other ongoing MeerKAT projects.

b) Software. The data reduction and analysis plan (including the description of pipelines and workflow for all components of the project as relevant) must be outlined in sufficient detail to provide confidence that the required outcomes can be achieved, with reduction at scale proceeding from the start of the project.

c) Hardware. Established access to the required tools and computing resources must be demonstrated. In this context, the proposers must indicate quantitative estimates of their storage and compute requirements.

The above must be connected as relevant to ongoing/previous activities with existing/prior MeerKAT large projects for which the current proposal is a continuation/adaptation.

By design, the foregoing is a very steep set of requirements. Experience has shown that ~300 hours on MeerKAT (or, depending on details, even ~100 hours) is a major project. The only XLP projects that will be selected are some of those that can demonstrate that they can deliver on their exceptional scientific promise, while starting suitable data reduction at scale immediately.

In this regard, the following are some generic examples that do not (necessarily or at all) demonstrate the required readiness: successful completion of a related MeerKAT project of a vastly different scale; ongoing reduction/analysis of a related MeerKAT project that has not yet yielded suitable scientific results; intent to use pipelines that have been successfully used for another ongoing large MeerKAT project (e.g., is the required hardware also available? Does the relevant team also have availability for the new project without slowing down the ongoing project?); successful analogous project at another telescope. 

In addition, XLPs must include a detailed public data release plan. Data Releases provide curated data products of scientific value to the broader astronomical community. The proposed DR plans must be specific: what types of data products are expected to be released, and on what timelines. The proposed timelines may be milestone dependent and/or calendar based. If an XLP has multiple themes (e.g., based on continuum, polarization, and HI data products), the DR plan must address all of the themes.

vi. Human Capital Development. It is expected that XLP projects will be used to train early career researchers. In particular, specific plans for PhD (and as relevant MSc) students should be indicated. Student names and affiliations as well as working project/thesis titles must be provided if available.

6 Review of Proposals

All valid proposals received under this CfP will be evaluated on the merits of their feasibility and Science Case. Large proposals and XLPs will receive particular scrutiny. 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.

Regular and Large proposals (Section 6.1) will be reviewed differently from XLPs (Section 6.2), and the corresponding reviews may proceed on somewhat different timelines.

6.1 Regular and Large proposals

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

i. The full Science Case (Section 5.1.2) will be reviewed by multiple Science Reviewers (anonymous domain experts), according to guidelines provided by SARAO. This will be done in dual-anonymous fashion (i.e., the reviewers will not have explicit knowledge of the identity of the proposing teams).

ii. The technical justification portion of the Science Case, and data analysis/management plan (Section 5.1.3), 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. The status of previous MeerKAT projects led by the PI and Technical Lead of the current proposal may also be considered.

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

6.2 XLPs

First, all submitted XLPs will be assessed to determine whether there are any that clearly do not meet the criteria of demonstrating that “the team is ready to reduce and analyze their data at scale from day 1” (Section 5.2.2). This will be done by SARAO with the assistance of external experts as needed.

Next, the full Science Case (Section 5.2.2) of all XLPs that pass the above assessment will be reviewed by multiple domain experts, according to XLP-specific guidelines provided by SARAO. The technical justification portion of the Science Case will also be reviewed by SARAO.

A Review Panel appointed by the MD will then consider the above inputs in light of specific guidelines and recommend to the MD a rank-ordered list of XLPs suitable for scheduling on MeerKAT. This panel may include non-conflicted members of the Review Panel considering Regular and Large proposals (Section 6.1) and draw on additional experts as needed.

6.3 Final disposition of proposals

SARAO aims to implement an appropriately balanced science program with a broad user base. 

As such, it is foreseen that the fraction of competed telescope time allocated to ‘very large projects’ (XLPs and remaining LSPs) will not exceed 50% of the time available for LSPs and OT5 projects during the immediate 12-month cycle covered by this CfP. In practice this implies that the aggregate time allocation for XLPs during the current cycle will likely not exceed ~1000 hours. In addition, depending on proposal pressure, XLPs may be limited in how much time they can be allocated within a particular LST range in order to retain flexibility for other projects. Also, otherwise meritorious XLPs may be considered against the specific science goals and status of MeerKAT LSPs, as well as the science goals of other XLPs, in order to select a balanced science portfolio of very large projects on MeerKAT.

The overall rankings of recommended Regular, Large, and XLP projects will be proposed to the MD by non-conflicted members of both the Regular/Large and XLP panels as needed.

Once the relevant review processes outlined above are completed, and after taking into account other relevant constraints (e.g., pressure for particular LSTs or night-time observing), SARAO will group proposals into three classes: A (will be observed); B (may be observed); C (will not be observed). As noted in Section 3.1.3, some Multi-year proposals may be conditionally pre-allocated time for ‘Year 2’ of their request in the context of OT5 reviews. All other Multi-year proposals will need to be resubmitted and evaluated against all proposals received in response to future CfPs. 

Following the above, all PIs will receive feedback on the disposition of their proposals, and suitable sections of the cover sheets of approved projects will be made public.

7 Timelines

This CfP is being issued on 1 June 2024.

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 15 July 2024.

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 late 2024. It is possible that A-rated Regular and Large projects will be announced before other approved projects.

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 (a) the date of last data collection for single-year projects; (b) the completion of yearly ‘observing seasons’ as relevant for Multi-year projects. 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. Relevant beamformed data will also become available at that time.

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 SARAO does not guarantee the storage of either visibility data or any associated image cubes substantially beyond the proprietary period of the observations. Teams are expected to download data from the MeerKAT archive soon after the observations, and 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.

Publications making use of the S-band receivers should in addition contain the acknowledgement statement provided in the S-band capability page; while publications making use of any User Supplied Equipment (USE) should also contain the relevant acknowledgement statements provided in their technical pages.

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.