Swedish LOFAR station proposals

For information about ​proposals for Directors Discretionary Time (DDT): see the general proposal page​.

Call for proposals

Proposals are invited for observations with the Swedish LOFAR station, located at Onsala Space Observatory, in the period April – August 2020.

Deadline: Friday 18 October 2019 (23:59:59 UTC)
(If you are considering submitting close to the deadline, please note that support will only be available during normal office hours.)
 
The Swedish LOFAR station, in the stand-alone configuration offered here, covers the frequency ranges 10–90 MHz and 110–240 MHz in two orthogonal linear polarisations. The maximum bandwidth is 100 MHz and can only be used for one of the frequency ranges mentioned above at a time.

Observing period and operations:

This Call for proposals is for the observing period 1 April – 31 August 2020. There is maximum 1 day/week available for the stand-alone observations.
 
The telescope is open for scientists from all countries. Co-operation with Swedish scientists is encouraged (but proposals will be evaluated solely on scientific merit).
 
Observations can be carried out remotely. There are observation tools available which are relatively easy to use, so detailed knowledge on how to operate a LOFAR station is not needed.​

Technical information

There are several data products that can be recorded from the station:

 
1.) The high data rate streams:
Up to 244 synthesized beams in the form of complex wave data delivered as individual streams in UDP packets over a 3 Gbit/s connection. Each stream is a subband of width 195 kHz at a cadence of 5.12 µs. In the normal operations mode, the maximum bandwidth for the high data-rate output is 48 MHz if all streams are beam-formed in the same direction. Alternatively, in the other extreme case, 244 different beams can be formed but will then only cover 195 kHz of bandwidth. There is thus a trade-space between number of digital beams and bandwidth per beam.
(Note: In an alternative operations mode, the subbands are 156 kHz wide at a cadence of 6.4 μs, and the high data-rate output is 38 MHz.)
 
2.) Low-cadence visibilities:
Station visibility matrices can be dumped in files integrated over one second, but only for a single subband at a time.
 
3.) Low-cadence beam-formed data:
This is the total power of each data stream integrated over one second, dumped in files.
 
4.) Low-cadence antenna/tile total power:
These are the total powers in all 512 subbands (80 or 100 MHz) of each antenna or tile signal integrated over one second and dumped in files.
 
5.) Full array temporal burst data:
Triggered capture of complex waveforms from all antenna elements in the array at 200 MHz sampling up to 8 s in duration.
 
At Onsala, we offer the possibility to record the high data-rate streams in continuous runs of durations of up to a maximum of 48 h (in practice, to leave disk space for data reduction, not more than 36 hours is recommended). After that, it is up to the project team to promptly reduce the observation so that the raw data can be removed to free up memory for subsequent observations. Processing capacity on the computers storing the data is available (proposers should check with local contacts before submitting if this processing capability is sufficient for their needs). In addition to CPU processing, we also provide a GPU capable of processing 2 of out 4 data lanes in real-time.
 
For data recording and analysis (such as dedispersion), we provide several options including LuMP, DSPSR, PSRCHIVE, and TEMPO2. On-the-fly data reduction may be possible as well. State clearly in the proposal what software you would like to use in that case and how much it would reduce the footprint of the data needed to be stored.
 
The sensitivity of the LOFAR station is exemplified in the following table (but see also the ASTRON web page Sensitivity of the LOFAR array):
 
Freq (MHz)​ ​15 ​30 ​45 ​60 ​75 ​120 ​150 ​180 ​210 ​240
​Sensitivity (mJy) ​1266 ​234 ​101 ​78 ​130 ​4.5 ​3.5 ​4.0 ​4.6 ​5.1

 

Theoretical LOFAR sensititvity (rms noise level) for 1 hour integration time, an effective bandwidth of 6 MHz and dual polarisation. A weighting factor of 1.3 is applied.

Proposal preparation and submission:

Onsala Space Observatory uses the NorthStar system for preparation and submission of proposals. NorthStar is used by several radio and optical observatories.
 
In NorthStar, information about applicants, instruments, targets, etc., is to be provided "on-line", and the scientific justification is to be prepared "off-line" and uploaded as a pdf file (also target lists can be uploaded). NorthStar then produces one pdf file with all information. NorthStar includes information on how to use it.
 
The proposal must contain a proper and concise scientific justification including an explanation for how the requested observing time was calculated, in total no more than two A4 pages long, plus figures and tables if needed (for a total of maximum six pages). Proposers should mention relevant previous observation with Onsala telescopes, and clearly show preliminary results. If observations are for Ph.D. work, this should be stated.

Further information


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Published: Fri 15 Aug 2014. Modified: Thu 19 Sep 2019