International LOFAR Telescope Regular Proposal Call
Open to the Worldwide Community
Submission deadline: Monday September 17, at 12 UT.
(this file in PDF format)
Cycle 0 will run from 01 December 2012 to 31 May 2013.
LOFAR is a powerful next-generation radio telescope for frequencies below 240 MHz that offers revolutionary new observing capabilities thanks to its phased-array technology with digital beam-forming. LOFAR Version 1 already allows novel and cutting-edge science projects, while considerable development is ongoing to reach the full potential of the International LOFAR Telescope (ILT).
Summary: Capabilities, Limitations
Detailed information about LOFAR’s capabilities is available online at www.astron.nl. On the main ASTRON website, navigate to Radio Observatory, LOFAR.
For Cycle 0, there is a limited but diverse set of standard observing capabilities. LOFAR software version 1 is now ready. It 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.
Proposers should take careful note of current limitations, such as on noise levels, field sizes and resolutions; examples of imaging sensitivities reached thus far in commissioning observations by experienced radio astronomers are given online.
Also, central computing and storage for data processing will be a limiting resource for many projects, and must be requested separately in addition to observing time; current indicative numbers are given online. Allocations of observing time and of central processing time to a given project will often be unequal, based on technical considerations and optimisation of the overall science yield of the ILT.
Vigorous work is ongoing to extend the performance, and to incorporate improvements into a standard imaging pipeline. On 01 September 2012, the Observatory will place a status update online. All projects require a careful technical justification, referring to that baseline performance and data quality, and, where appropriate, discussing expertise, tools, manpower, and computing capacity required either from the ILT and/or supported within the proposing team. Further details are given below.
Regular Proposals are solicited from any group in the worldwide community. These will be uniformly reviewed for 1058 hours of observing and 1058 hours of central processing in total, which is all remaining unallocated time in Cycle 0.
Of this, 817 hours of observing and 817 hours of processing will be allocated in tandem between national consortia and the independent Programme Committee (PC); these allocations may reflect national interests (detailed mechanism online).
The remaining 241 hours of observing and 241 hours of processing will be allocated by the PC alone, under an Open Skies policy based solely on scientific merit and technical feasibility. The Open Skies fraction will rise in future years.
Earlier, in response to Reserved Access proposals, another 1351 hours have been allocated already at an “umbrella” level. Now, the PC and the national consortia will be detailing those allocations for Cycle 0. This will be done on the basis of the Regular Proposals submitted by the involved teams; those PIs will receive further instructions separately. Particulars of the Reserved Access proposals and umbrella allocations can be viewed publicly online.
Important further instructions and information
Data processing resources needed
In addition to observing time requests, Regular Proposals also must include requests for required processing and storage resources. Information for various use cases is given online. In particular, the benchmarked automatic pre-processing and imaging pipeline run times scale strongly with array size, field size and resolution, and in many cases considerably exceed the observing time.
Allocations of processing times on the ILT central processing system far in excess of observing times will only be possible for exceptionally interesting science projects of modest size. In addition, proposals may justify a data reduction plan where, after initial steps on the ILT central processors, data is copied from the ILT archive to privately maintained external resources and software for further processing.
Advanced use; experts and non-experts
The standard capabilities and performance published on 01 September 2012 must be used as the baseline in the technical justification of the proposal. It is expected that the capabilities and user-friendliness of LOFAR will significantly improve in the coming cycles. Expert users may already be able to profit from some of these improvements earlier, but for Cycle 0 the ILT does not guarantee any availability beyond that published on 01 September 2012. If further functionality or performance is crucial for their proposal, the ability of the group to reach their extended goals must be appropriately demonstrated.
Groups with relevant expertise may include a carefully argued technical request to carry out other/further analysis steps on the ILT central processing system for any imaging or non-imaging application, bearing in mind the scarcity of these resources. Of course, as above, the technical case may in addition justify how, starting from the standard initial data or pipeline products, or after some particular central processing, the group will carry out specific additional processing on data from the archive with privately maintained external computing resources and software.
A few of the most meritorious proposals from less experienced groups can be earmarked by the PC for (semi)manual further central data processing steps and Observatory support staff assistance, on a best-efforts basis and limited by scarcity of processing resources.
Data policies; shared observations
Groups will obtain from the PC specific rights to use LOFAR data in response to their proposals. The data themselves remain the property of the ILT. Data rights are by default granted for a one-year proprietary period, after which the data become public. Exceptions can be proposed to the PC; extensions of the proprietary period will only be granted in rare cases. Furthermore, deposition of refined “final” data products into the ILT archive may be offered by the proposers, or can be stipulated by the PC.
The same data may be assigned to different teams, to be used for different purposes. Proposals may include “commensal observing”, for example to allow certain forms of transient patrols or cosmic ray event monitoring during imaging or beamformed observations for another primary project. The PC will assign conditions such as precedence with regard to observing setup, interrupt rights, and so on. Proposals may also be for purely offline use (but possibly with processing time) for different science goals using data in the archive that is to be obtained with Reserved Access project allocations, or with other proposals known to the proposers. Hence the intended observing strategy and data use have to be clearly delineated by the proposers. If teams foresee the likelihood of conflicts, it is advisable to address this in the respective proposals up-front; jointly preferred solutions may be suggested in both proposals.
Detailed rules for each case will be set by the PC, based on the PC mandate to maximise the overall science output of the ILT, and covering the circumstances that can be foreseen with the proposals at hand. The ILT Director will decide on any further eventualities.
Proposers must use the online submission tool NorthStar and adhere strictly to the instructions concerning format and content given online. The proposals should make their case in a fully self-contained science and technical justification, uploaded as an A4 pdf file of at most 6 pages in minimally 11pt font. A second file of at most 3 pages can be uploaded with ancillary material, such as tables, additional figures, publication lists, etc. Titles and abstracts of allocated Regular Proposals will become public, the rest of the proposal materials will remain confidential.
Further questions can be addressed to the Radio Observatory science support group: sciencesupport [at] astron [dot] nl
Director International LOFAR Telescope