User Parameters - Data Location & Beam SelectionΒΆ

The following parameters determine where the measurement sets are that hold the data to be processed. The default behaviour is to read the MS from the given Scheduling Block (SB) directory. If SB numbers are given, this is where to look. The location for these SB directories is given by DIR_SB. If SB numbers are not provided, however, the MS_INPUT variables give the filename for the relevant MS. The full path must be specified here.

The measurement sets presented in the scheduling block directories have a variety of forms:

  1. The earliest observations had all beams in a single measurement set. For these, splitting with mssplit is required to get a single-beam MS used for processing.
  2. Many observations have one beam per MS. If no selection of channels or fields or scans is required, these can be copied rather than split. Note that splitting of the bandpass observations are necessary, to isolate the relevant scan.
  3. Recent large observations have more than one MS per beam, split in frequency chunks. The pipeline will merge these to form a single local MS for each beam. If splitting (of channels, fields or scans) is required, this is done first, before merging the local subsets.

In the multiple-file modes, the metadata for the observation is taken from a single MS (although they should all be the same for a given observation).

If no channel or scan selection is being made (that is, CHANNEL_RANGE_SCIENCE or SCAN_SELECTION_SCIENCE are not given), there is only a single field in the dataset, and the observation used the MS-per-beam mode, then instead of splitting the dataset the pipeline simply copies the archive MS to the output directory. This should run faster than using mssplit.

The bandpass calibration datasets are treated the same way, although mssplit is always used (since the relevant scan needs to be split out).

It may be that the SB you wish to process has been removed from /astro. You can follow the instructions on Commissioning Archive Platform to request it be reinstated. If you have already started processing it and wish to continue, you can specify the measurement set name it would have (this forms the metadata/mslist_ filename), using the parameters MS_INPUT_1934 or MS_INPUT_SCIENCE, and the scripts will recognise the metadata file and continue. For anything to be done, it requires you to have already run the splitting, so that there is a local copy of the individual beam data.

Variable Default Description
DIR_SB /askapbuffer/payne/askap-scheduling-blocks Location (on galaxy) of the scheduling blocks. This is used when specifying SB numbers - the default is the standard location for ASKAP operation. If blank (""), the MS used will be given by MS_INPUT_SCIENCE and MS_INPUT_1934.
SB_1934 no default SB number for the 1934-638 calibration observation.
MS_INPUT_1934 no default MS for the 1934-638 observation. Ignored if the SB number is provided.
SB_SCIENCE no default SB number for the science field observation.
MS_INPUT_SCIENCE no default MS for the science field. Ignored if the SB number is provided.

These parameters determine which beams in the data to process. The beams can be listed explicitly via the BEAMLIST parameter, given as a comma-separated list of beams and beam ranges, such as "0,1,4,7,8-10". Alternatively (and if BEAMLIST is not provided), the BEAM_MIN and BEAM_MAX parameters are used to specify an inclusive range. Note that in all cases the beams are numbered from zero (ie. beam 0 is the first beam in the measurement set).

The beams used for the bandpass calibrator will be all beams up to the maximum beam requested for the science dataset (either BEAM_MAX or the largest number in BEAMLIST).

The beam list will be limited by the number of beams available in the footprints for both the science and bandpass calibrator datasets. If more beams are requested via BEAMLIST or BEAM_MAX, then a warning message is given and the list trimmed to match the limits from the relevant scheduling blocks.

Variable Default Description
BEAMLIST "" A comma-separated list of beams and beam ranges (for instance "0,1,4,7,8-10"), to specify the set of beams than should be processed from the science observation. Beam numbers are 0-based.
BEAM_MIN 0 First beam number (0-based). Used when BEAMLIST is not given. All beams from BEAM_MIN to BEAM_MAX inclusive are used for the science processing.
BEAM_MAX 35 Final beam number (0-based), to go with BEAM_MIN.