hifa_bpsolint

hifa_bpsolint(vis=None, field=None, intent=None, spw=None, phaseupsnr=None, minphaseupints=None, evenbpints=None, bpsnr=None, minbpsnr=None, minbpnchan=None, hm_nantennas=None, maxfracflagged=None) → ResultsList[Results][source]

Compute optimal bandpass calibration solution intervals.

The task estimates the optimal time and frequency solution intervals needed to achieve the required signal-to-noise ratio. This estimation is based on nominal ALMA array characteristics and the observation's metadata.

The phaseup gain time and bandpass frequency intervals are determined as follows:

  • For each data set the list of source(s) to use for bandpass solution signal-to-noise estimation is compiled based on the values of the field, intent, and spw parameters.

  • Source fluxes are determined for each spw and source combination.

  • Fluxes in Jy are derived from the pipeline context.

  • Pipeline context fluxes are derived from the online flux calibrator catalog, the ASDM, or the user via the flux.csv file.

  • If no fluxes are available the task terminates.

  • Atmospheric calibration and observations scans are determined for each spw and source combination.

  • If intent is set to 'PHASE' are there are no atmospheric scans associated with the 'PHASE' calibrator, 'TARGET' atmospheric scans will be used instead.

  • If atmospheric scans cannot be associated with any of the spw and source combinations the task terminates.

  • Science spws are mapped to atmospheric spws for each science spw and source combination.

  • If mappings cannot be determined for any of the spws the task terminates.

  • The median Tsys value for each atmospheric spw and source combination is determined from the SYSCAL table. Medians are computed first by channel, then by antenna, in order to reduce sensitivity to deviant values.

  • The science spw parameters, exposure time(s), and integration time(s) are determined.

  • The phase-up time interval, in time units and number of integrations required to meet the phaseupsnr are computed, along with the sensitivity in mJy and the signal-to-noise per integration. Nominal Tsys and sensitivity values per receiver band provided by the ALMA project are used for this estimate.

  • Warnings are issued if estimated phase-up gain time solution would contain fewer than minphaseupints solutions.

  • The frequency interval, in MHz and number of channels required to meet the bpsnr are computed, along with the per channel sensitivity in mJy and the per channel signal-to-noise. Nominal Tsys and sensitivity values per receiver band provided by the ALMA project are used for this estimate.

  • Warnings are issued if estimated bandpass solution would contain fewer than minbpnchan solutions.

  • If strong atmospheric features are detected in the Tsys spectrum for a given spw, the frequency interval of bandpass solution is recalculated to meet the lower threshold minbpsnr, i.e., a lower snr is tolerated in order to preserve enough frequency intervals to capture the atmospheric line.

Parameters:

  • vis --

    The list of input MeasurementSets. Defaults to the list of MeasurementSets specified in the pipeline context.

    Example: vis=['M82A.ms', 'M82B.ms']

  • field --

    The list of field names of sources to be used for signal-to-noise estimation. Defaults to all fields with the standard intent.

    Example: field='3C279'

  • intent --

    A string containing a comma delimited list of intents against which the selected fields are matched. Defaults to 'BANDPASS'.

    Example: intent='PHASE'

  • spw --

    The list of spectral windows and channels for which gain solutions are computed. Defaults to all the science spectral windows for which there are both 'intent' and TARGET intents.

    Example: spw='13,15'

  • phaseupsnr --

    The required phase-up gain time interval solution signal-to-noise.

    Example: phaseupsnr=10.0

  • minphaseupints --

    The minimum number of time intervals in the phase-up gain solution.

    Example: minphaseupints=4

  • evenbpints -- Use a bandpass frequency solint that is an integer divisor of the spw bandwidth, to prevent the occurrence of one narrower fractional frequency interval.

  • bpsnr --

    The required bandpass frequency interval solution signal-to-noise.

    Example: bpsnr=30.0

  • minbpsnr --

    The minimum required bandpass frequency interval solution signal-to-noise when strong atmospheric lines exist in Tsys spectra.

    Example: minbpsnr=10.0

  • minbpnchan --

    The minimum number of frequency intervals in the bandpass solution.

    Example: minbpnchan=16

  • hm_nantennas --

    The heuristics for determines the number of antennas to use in the signal-to-noise estimate. The options are 'all' and 'unflagged'. The 'unflagged' options is not currently supported.

    Example: hm_nantennas='unflagged'

  • maxfracflagged --

    The maximum fraction of an antenna that can be flagged before it is excluded from the signal-to-noise estimate.

    Example: maxfracflagged=0.80

Returns:

The results object for the pipeline task is returned.

Examples

1. Estimate the phaseup gain time interval and the bandpass frequency interval required to match the desired signal-to-noise for bandpass solutions:

>>> hifa_bpsolint()