International LOFAR Telescope
Proposal Call to the Worldwide Community
Cycle 7: 15 Nov 2016 - 14 May 2017
Submission deadline Wednesday 14 September 2016, 12 UT
Submission only via the online tool NorthStar.
** Proposers must ensure that their justification files adhere to the instructions given below and in Northstar, repeated online here. **
SYSTEM CAPABILITIES: The International LOFAR Telescope (ILT) 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 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. For Cycle 7, pipeline processing will be performed on the new CEP4 cluster, which is being commissioned at the moment. The high resolution (arcsecond) imaging capability of the array has been significantly enhanced with the addition of three stations in Poland, bringing the total number to 38 in the Netherlands and 12 in other European countries. LOFAR capabilities are described in detail online.
COMMUNITY ACCESS: Time on the ILT is available to scientists from the worldwide community. For Cycle 7 60% of the total time is allocated through Open Skies rules, while the remainder is allocated in tandem between national consortia and the independent Programme Committee (PC). Scientific and technical strengths of the proposals are taken along in the evaluations. In view of the novel and evolving character of the ILT, first-time proposers are strongly urged to get in contact with Science Support at ASTRON well ahead of the deadline, or to seek suitable collaborators; novice groups should also consider keeping the scope of initial projects modest while they become familiar with the complexities of data handling and analysis.
TIME AND DATA RIGHTS: Allocations will consist mostly of all of the remaining observing time and/or processing resources in Cycle 7. There are 630 hrs already reserved for ongoing long-term projects; this will be complemented by at least 970 observing hrs in Cycle 7, which could all be observed at night. Further observing time in Cycle 7 may be allocated by the PC at lower priority, subject to technical advice on the impact of specific observing types on the queue for post-processing; this will be calibrated in part based on early experience with running CEP4; particularly investigators with large programs in mind may wish to follow the LOFAR Status Meetings close to the submission deadline, for information explicitly addressing the likely impact of various kinds of observations. There will be 1979 processing hours available; restrictions on total data storage in the archive (3 PB available per semester) will also be taken into account. The 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.
LONG-TERM PROPOSALS: The Cycle 8 long-term time portion that was available for pre-allocation has already been fully assigned in response to the Cycle 5 deadline. The remainder of the Cycle 8 time will be filled with a proposal deadline in March 2017, which will be open to both existing and new projects. The ILT is planning to restructure its long-term observing queue to better suit the needs of its users. Cycle 9, with deadline in September 2017, is intended to allow the (re)start of significant longer-term projects. The ILT-PC has imposed conditions on all existing long-term allocation, and in particular has typically required a satisfactory progress report before releasing later parts of an assigned allocation; people with existing long-term allocations are reminded to submit such reports as needed.
PROCESSOR REQUESTS: Each proposal must request processing time to match the observing time within appropriate documented ratios, or should justify how processing will proceed elsewhere. When doing so, they should also clearly mention the amount of processing hours that the PC could safely subtract from their request, might this be needed in case of a large oversubscription in the next Cycle.
The new CEP4 cluster will replace CEP2 during the coming few weeks, after a period of commissioning. Whether or not larger amounts of processing hours than currently advertised might then become available for Cycle processing will be assessed after the characterization of the processing performance of CEP4, which will follow the commissioning phase. Results will be shared with the users in due course at the LOFAR Status Meetings.
CO-OBSERVING WITH THE SURVEYS KSP PROGRAMME: in Cycle 7 the International LOFAR Telescope encourages co-observing and co-processing of data for the Surveys KSP team and the PIs of standalone Cycle proposals requiring targeted imaging. By utilizing the multi-beam capability of LOFAR, some Surveys KSP Tier-1 pointings could be observed alongside other science targets, maximizing the telescope efficiency.
As a benefit of co-observing, the PIs of the standalone projects will receive the standard results of the data processing performed by the Surveys KSP team (see details online). There will be no requirement for joint science analysis or publications.
To apply for this option, the observing setup of the standalone project should be the same as that of Surveys KSP Tier-1 observations (see details online). Any of the Cycle 7 proposers interested in this opportunity should clearly state so in the technical section of their proposals. Moreover, they should confirm that their observations can adopt the Surveys KSP Tier-1 observing and processing setup.
Important further instructions and information
Cycle 7 will run from 15 November 2016 to 14 May 2017.
There are 630 hrs already reserved for ongoing long-term projects; this will be complemented by at least 970 observing hrs in Cycle 7, which could all be observed at night. Further observing time in Cycle 7 may be allocated by the PC at lower priority, subject to technical advice on the impact of specific observing types on the queue for post-processing; this will be calibrated in part based on early experience with running CEP4. There will be 1979 processing hours available.
Allocations will consist of observing time and/or processing resources in Cycle 7 only; no multi-cycle allocations will be made resulting from proposals for this deadline. The Cycle 8 long-term time portion that was available for pre-allocation has already been fully assigned in response to the Cycle 5 deadline.
Proposals must be self-contained (except that proposals that aim to share parts of surveys or other larger overlapping sets of observations may have an Envelope Sheet as an additional technical supplement).
Proposals must be typeset in 11pt font, or larger.
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 8 pages:
1. 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. For any proposal that has an associated Envelope Sheet, 2 pages are subtracted from the allowance for the main proposal, but at least 4 pages will always be allowed for the main proposal
3. For a Long-Term proposal, the observing time requested is added up over all cycles to determine the page limit
4. A Long-Term proposal that has no associated Envelope Sheet may take 2 additional pages, but devoted only to information project phasing, management plan, etc. The total allowed is never more than 8 pages
5. An Envelope Sheet has a limit of 5 pages
Proposals exceeding the page limits will be rejected.
Proposers must use the online submission tool NorthStar.
Science and Technical justifications
All Proposals must contain a cohesive, focused science justification for a specific research project.
All projects also require a careful technical justification, referring to the baseline performance and data quality described online, and, where appropriate, discussing expertise, tools, manpower, and computing capacity required either from the ILT and/or supported within the proposing team. In particular, the proposals must include detailed information on (i) instrument setup, (ii) desired sensitivity, (iii) data volume, (iv) processing strategy through automatic pipelines, (v) post processing strategy. Proposers should take careful note of guidelines and limitations, such as on maximum field sizes, resolutions, and achievable noise levels in automatic pipeline runs. The technical justification should be entered by completing the "technical questions" section within the Northstar tool and by adding any remaining technical detail in the justification file.
Requests for night time must be explicitly indicated and justified.
Each proposal must be self-contained except that an "Envelope Sheet" may additionally be used as a joint TECHNICAL supplement, when several proposals aim to share parts of surveys or other larger overlapping sets of observations; these can explain the broader observing and processing setups and plans, but not the individual science cases.
Data processing resources
In addition to observing time requests, all proposals also must include requests for required data processing and storage resources. Access to the CEP3 cluster for advanced processing by users should be mentioned in the proposal, as well as any envisioned additional use of ILT-related facilities in Amsterdam or Juelich for offline processing (see details online). Central computing and storage for data processing will be a limiting resource for many projects.
Automatic pre-processing and imaging pipeline run times scale strongly with field size and resolution, and in many cases considerably exceed the observing time (see details 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. 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.
The standard capabilities and performance published online 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 6 the ILT does not guarantee any availability beyond that published online. 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.
Proprietary time and other data policies
Groups will obtain from the PC specific rights to use LOFAR data in response to their proposals. The data themselves, as observed and as obtained from the standard pipelines run on ILT computers, remain the property of the ILT. Data rights for specific science 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 "derived" data products into the ILT archive may be offered by the proposers, or can be stipulated by the PC; by default these further products are the property of the proposers.
The same observed data or standard pipeline products may be assigned to different teams, to be used for different science 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. When doing this, the request should obviously be in line with the current capabilities of the instrument (see the online documentation). 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 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.
Further questions can be addressed to the Radio Observatory science support group: sciencesupport [at] astron [dot] nl