# Instructions

Instructions

## Proposal Call to the Worldwide Community

International LOFAR Telescope

Cycle 18: 01 June 2022 – 30 November 2022

Submission deadline Wednesday 09 March 2022, 12 UT

Submission only via the online tool NorthStar.

** Proposers must ensure their justification files adhere to the instructions given in Northstar, including restrictions on formats and proposal length, repeated below here. **

### WORLD-WIDE ACCESS:

Time on the ILT is available to scientists from the worldwide community. The single-cycle time offered in this call is allocated in tandem between National Consortia and the ILT-PC. Scientific excellence and breadth as well as the technical strength of the proposals are taken along in the evaluations. The ILT-PC will define restricted data access rights (default period 1 year) based on the specific science goals and arguments in the proposal. Other groups may be allocated simultaneous access for different science.

### SINGLE-CYCLE ONLY:

For Cycle 18, only single-cycle proposals are invited in any supported general-user mode. Single-cycle projects should achieve their science goals with an allocation only in the upcoming semester (1 June 2022 - 30 November 2022). Proposals to supplement Long-Term science already reviewed following previous deadlines are not eligible for the present call; pursuit of follow-up science related to results already in hand may be proposed.

### LST AND OTHER RESOURCE AVAILABILITY:

LST availability: The availability of observing time as a function of LST after taking into account the already active long-term projects is presented here. Some further limitations due to tentative allocations made to Long Term proposals are not shown, since the ILT-PC may still tension off the merits of Cycle 18 proposals for that time.

Processing time and/or data storage capacity: These can be limiting resources. Each proposal must request processing time to match the observing time within appropriate documented ratios (see documentation online), or should justify how processing will proceed elsewhere.

Support staff effort required to support the proposed projects is taken into account during allocation. An online tool is available to understand whether a proposal entails a low, medium, or high support load of the Science Data Centre Operations staff. During the allocation process, the ILT-PC will be advised about the amounts of support effort requested and available, and these will be used as boundary conditions for proposal allocations; support will be treated as a scarce resource in the same way as has become customary on LOFAR for processing and data storage resources.  Advice is available online on how proposers can reduce the support load of their project by a prudent choice of observing mode. The proposal may also indicate that the support will be carried out by members of the proposing team; in that case, both the expertise and the work plan must be carefully argued in the proposal.

Priority classes: Due to ongoing upgrade work, system availability and stability will vary with time. The ILT-PC will classify observing allocations as A and/or B priority time; roughly half in each. Allocations in A priority will have a high likelihood to yield a successful observation; in case such an observation suffers substantial failures, it will be repeated (once) at a later date. Allocations in priority B will likely be realized partially; they are carried out on a best-efforts basis, where the total of all priority B allocations requires an optimistic availability scenario.

### SYSTEM CAPABILITIES:

The ILT is a powerful radio telescope for frequencies below 240 MHz that offers state-of-the-art observing capabilities thanks to its phased-array technology with digital beam-forming. LOFAR delivers correlated visibility data for synthesis imaging, plus (in)coherently-added single and multiple station data (several beam-formed modes) as well as transient buffer read-out, for example for studies of pulsars, transients, and cosmic rays. LOFAR capabilities are described in detail online. Note the restrictions on functionalities offered in Cycle 18, as described in this page. Proposals should request only the available system observing modes and functionalities described online.

### CO-OBSERVING OPTION FOR STANDARD HBA OR LBA IMAGING WITH LOFAR SKY SURVEYS:

the possibility is offered to carry out imaging in co-observing mode with the LOFAR Survey projects, in their standard operating mode. This has the advantage for co-observing PIs that calibration and standard imaging are a routine process under guidance by the survey teams (see details here for HBA and here for LBA).

### PILOT LINC PROJECT:

ASTRON is currently implementing in production LINC, the direction-independent calibration pipeline, which produces direction-independent calibrated visibilities and wide-band images of the target field, and diagnostic plots. Details about this pipeline, including its performance, are given online. While LINC cannot yet be widely offered in Cycle 18, we will select a sample of appropriate projects that will be given the opportunity to obtain data products processed through this pipeline. In this respect, PIs who are interested in taking advantage of this option for the reduction of their data should clearly indicate that in the technical justification of their proposals.

### FURTHER PROPOSAL REQUIREMENTS:

•     For all proposals, the technical case must argue both the optimal and the minimal required total amount of time and other resources (and any requirements on cadence or time span). If the stated minimum time or other requirements cannot be allocated, the proposal will not be carried out at all.
•     Proposals for multiple observations must list and argue the preferred priority order; this will be considered by the ILT-PC along with other factors in making (possibly partial) allocations.
•     Proposers are required to verify whether any relevant data are already available in the LOFAR Long Term Archive.

In view of the novel and evolving character of the ILT, proposers are strongly urged to get in contact with Science Data Center Operations through the JIRA helpdesk well ahead of the deadline. Novice groups may wish to seek or request to be connected to suitable collaborators, and should also consider keeping the scope of initial projects modest while they become familiar with the complexities of data handling and analysis.

The Science Data Centre Operations group will explore the possibility for a few users unfamiliar with the reduction of LOFAR data to come to ASTRON (or have online interaction) for assistance with this. If this is desired, it must be specified in the proposal. Limited travel subsidies for eligible users can be supported through the Horizon-Europe ORP project. Further details are given online.

Dr. R.C. Vermeulen

Director, International LOFAR Telescope

## Target List Order

If proposals request multiple observations (e.g. multiple fields/pointings, or multiple instrumental settings) these will be taken in all cases to be listed in decreasing order of preference/priority of the proposers. In case only a partial allocation can be made, the ILT-PC may, based on its science assessment, decide to deviate from the proposed priorities, but the proposer priorities must anyway be clear in advance.

It will be assumed when dynamic scheduling is carried out that the list of targets is in priority order.

## Target Declination Limits

As a phased-array system installed on level ground, LOFAR has greatest sensitivity when observing at high elevations.  Below approximately 30 degrees elevation sensitivity drops significantly such that the Sun becomes the only viable target for interferometric observation below about 10 degrees elevation.

Commissioning observations have managed successful imaging of a target at -7 degrees declination, but imaging is not straightforward and the following points need to be noted:

• The thermal noise cannot be attained at these declinations;
• Short baselines have to be flagged;
• Some additional flagging of data may be required.

Furthermore, the shorter length of time that such targets are above a useable horizon can severely limit the u-v coverage attainable.  Therefore for interferometric observations, -5 degrees declination should be regarded as a lower limit and targets should preferably be above the celestial equator.  Proposers wishing to image targets below the celestial equator are expected to justify that their observing programme can attain the sensitivity and/or u-v coverage required.

Pulsar observations have been successfully carried out in beam-formed mode at declinations down to -29 degrees.  In this mode, the main limitation is the sensitivity required and the duration of observation needed to attain this sensitivity.

Support availability and User Shared Support Mode during cycle 18

To calculate the support level required for your project please use this tool.

To maximize the telescope observing hours on sky, more observing hours have been offered than can be supported by ASTRON. Therefore, users can assist in running their own projects in a “user shared-support mode”. To this aim, proposers should state it in the proposal, indicating that they are able to provide experienced personnel to the support activities of their full project (see details below). In this model, ASTRON personnel would only have a supervisory role. In addition, this page explains which functionality requires a higher or lower support load.

Project support consists of several labour-intensive or critical activities, such as

• scheduling
• preparing observations
• reporting
• data handling

Depending on the specific characteristics of a project, the amount of support required can vary. When preparing a proposal, a tool is provided to determine the support load of a project (high, average or low). A detailed assessment of the amount of support needed (in hours) will be performed in the review process itself by the ASTRON personnel. This amount will be treated as a limited resource. Projects requiring a high degree of support should really consider using the ‘user shared support’ mode. More details about the project features that can raise the degree of support are explained below.

User shared-support mode

Science teams that have proven expertise in particular LOFAR observing modes and/or observing support procedures can provide personnel to handle the support workload for their full project, i.e. users are expected to handle their own projects for the full budget of allocated telescope time. This should be clearly written in the proposal. Before the start of each cycle, these users will be updated by ASTRON on current procedures & tools to handle the data flow for their project.

Examples of project features requiring high levels of support include, but are not limited to:

• Short observations or sets of observations, especially when scheduled on different days. e.g., 2 hour interferometric observations, “lucky imaging” and “interleaved observations”.
• Parallel observations (e.g. commonly used setups for scintillometry and solar studies.
• Restrictive scheduling constraints, e.g., at specific orbital phases; commensal with other telescopes;
• Responsive Telescope
• Updates to target lists during the cycles
• Manual execution of system tasks (e.g. dynamic spectrum pipeline, manual ingests)
• Multi-beam observations with >4 beams

Projects can lower the required level of support by ASTRON by adopting the following criteria:

• Large fraction of user support in administering the project [ “user shared support mode”, explained in the previous Section]
• In particular, projects satisfying all or most of the requirements below are considered low support:
• can use randomly occurring time slots with no LST constrain and flexible duration
• can be rapidly started, e.g. because their setup does not require changes or can be automatically selected
• are conducted almost entirely by the project team with little or no involvement from Observatory staff.
• have significant independent processing resources and place little or no pressure on the ILT data processing queue.
• have significant flexibility in terms of the minimum number of stations required.

## Instructions for Justification File Preparation

Instructions for the NorthStar justification file:

The proposers should make their case in a fully self-contained science justification, uploaded as an A4 pdf file. The page-limit for the pdf-file varies per call for proposals. The document should include the science justification, additional technical information that is not provided in the "technical questions" section within the Northstar tool, and any desired ancillary material such as figures and tables.

Page limits are dependent on the amount of observing time requested. The total of the science and technical justification, including any desired figures and tabular material, will have page limit of 4 pages for small requests, and the following rules may increase this limit to at most 10 pages:

1. Single-Cycle proposals: the base allowance is 3 pages, plus 1 page per 250 hours of observing time requested (request 1 hour: 4 pages, from 251 hours: 5 pages, ... from 1001 hours: 8 pages).
2. Long-term proposals follow the same rule as above, but 2 extra pages are allowed.
3. Progress reports for long-term active project have a limit of 3 pages.

EXAMPLE: the maximum, in case>1000 hrs are requested, is 8 pages for single-cycle proposals, 10 pages for for long-term proposals.

Proposals exceeding the page limits will be rejected.

For long-term proposals, any specific requirement about how the observing time should be distributed between the four cycles must be clearly specified in the justification document. If this information cannot be found, it will be assumed that the observing time can be distributed equally between the four cycles.

Northstar accepts uploads of a single pdf file with a minimum font size of 11 pt (12 pt recommended). The pdf can be generated from, e.g., Microsoft Word, LaTeX and through several other routes at the proposer's choice. An example latex template is provided below with the appropriate sections and descriptions. Note: all PI's should check the pdf of the proposal BEFORE submission, making sure that text is not overlapping with headers and, in general, that no layout issues are present that make text unreadable. Proposals affected by layout issues may be rejected.

For a proposal to be fully considered submitted, the pdf file should contain at least the following sections:

1 Scientific Rationale

Scientific justification of the proposal

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%% Example TEX file %%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%% Howto generate the pdf %%%%%%
%-> latex template.tex
%-> dvipdf template.dvi
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\documentclass[a4paper,12pt]{article}
\oddsidemargin=-0.54cm
\evensidemargin=-0.54cm
\topmargin=-1cm
\textwidth=17cm
\textheight=22cm
\pagestyle{empty}
\begin{document}
%%%% Title of proposal
\begin{center}
{\bf \Large Proposal Title} \\*[3mm]
\end{center}

\section{Scientific Rationale}

%%%% TEXT OF JUSTIFICATION HERE!

%%%% Non-mandatory sections

% \section{Technical Addendum}

%%%% Additional technical justification which is not covered in the "Technical questions" section of the Northstar tool

%%%% Example sections for additional technical information

% \subsection{Sensitivity and instrument setup}
% \subsection{data volumes/rates}
% \subsection{Processing requirements}
% \subsection{Data storage and LTA requirements}
\end{document}