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: http://www.atnf.csiro.au/computing/software/miriad/doc/selfcal.html
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Task: selfcal Purpose: Determine self-calibration of calibration gains. Categories: calibration, map making SELFCAL is a MIRIAD task to perform self-calibration of visibility data. Either phase only or amplitude and phase calibration can be performed. The input to SELCAL are a visibility data file, and model images. This program then calculates the visibilities corresponding to the model, accumulates the statistics needed to determine the antenna solutions, and then calculates the self-cal solutions. Key: vis Name of input visibility data file. No default. Key: select Standard uv data selection criteria. See the help on select for more information. Key: model Name of the input models. Several models can be given, which can cover different channel ranges and different pointing and sources of the input visibility data. Generally the model should be derived (by mapping and deconvolution) from the input visibility file, so that the channels in the model correspond to channels in the visibility file. The units of the model MUST be Jy/pixel, rather than Jy/beam, and should be weighted by the primary beam. The task DEMOS can be used to extract primary beam weighted models from a mosaiced image. If no models are given, a point source model is assumed. NOTE: When you give SELFCAL a model, it will, by default, select the data associated with this model from the visibility data- set. This includes selecting the appropriate range of channels and the appropriate pointing/source (if options=mosaic is used). If you use a point source model, if it YOUR responsibility to select the appropriate data. Key: clip Clip level. For models of intensity, any pixels below the clip level are set to zero. For models of Stokes Q,U,V, or MFS I*alpha models, any pixels whose absolute value is below the clip level are set to zero. Default is 0. Key: interval The length of time, in minutes, of a gain solution. Default is 5, but use a larger value in cases of poor signal-to-noise, or if the atmosphere and instrument is fairly stable. Key: nfbin The number of frequency bins. The default is 1. Use nfbin>1 to solve for variation across the band in the gains. Works best for uv files with a single spectral window, i.e., after uvsplit. Key: options This gives several processing options. Possible values are: amplitude Perform amplitude and phase self-cal. phase Perform phase only self-cal. mfs This is used if there is a single plane in the input model, which is assumed to represent the image at all frequencies. This should also be used if the model has been derived from MFCLEAN. mmfs Same as mfs, but with multiple input models, each applying to a subset of the bandwidth. For use with nfbin>1: models will be allocated to bins based on their centre frequency. relax Relax the convergence criteria. This is useful when selfcal'ing with a very poor model. noscale Do not scale the gains. By default the gains are scaled so that the rms gain amplitude is 1. In this way, the total flux is not constrained to agree with the model. If you are using nfbin>1 you may need this to make the data follow the spectral shape of the model. mosaic This causes SELFCAL to select only those visibilities whose observing center is within plus or minus three pixels of the model reference pixel. This is needed if there are multiple pointings or multiple sources in the input uv file. By default no observing center selection is performed. Note that "amplitude" and "phase" are mutually exclusive. The default is options=phase. Key: minants Data at a given solution interval is deleted if there are fewer than MinAnts antennae operative during the solution interval. The default is 3 for options=phase and 4 for options=amplitude. Key: refant This sets the reference antenna, which is given a phase angle of zero. The default, for a given solution interval, is the antenna with the greatest weight. Key: flux If MODEL is blank, then the flux density (Jy) of a point source model can be specified here. The default is 1. Additional spectral parameters can be specified as follows: Reference frequency in GHz, spectral index, up to two higher order alpha terms (as produced by uvsfit or uvfmeas with options=mfflux) Key: offset This gives the offset in arcseconds of a point source model (the offset is positive to the north and to the east). This parameter is used if the MODEL parameter is blank. The default is 0,0. The amplitude of the point source is chosen so that flux in the model is the same as the visibility flux. Key: line The visibility linetype to use, in the standard form, viz: type,nchan,start,width,step Generally if there is an input model, this parameter defaults to the linetype parameters used to construct the map. If you wish to override this, or if the info is not in the header, or if you are using a point source model, this parameter can be useful. Revision: 1.19, 2016/01/28 22:07:15 UTC