Content-type: text/html Manpage of gplist


Section: User Commands (1)
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gplist - List gains table and optionally overwrite calibration  






GpList is a Miriad task to list the amplitude gains in a gains table and (optionally) replace the amplitude information in a gains table with constants of the users choosing, and/or simultaneously
  setting the phase corrections to zero.

WARNING: if you modify the gains, the resulting amplitude gains will be

         constant with time! The original gains table is overwritten.

The motivation for this routine arose from BIMA datasets in which the calibrator is weak so that conventional amplitude calibration was not very successful. This was compounded by old BIMA ant3 being blown about by the wind. The source, on the other hand, was strong but time variable, hence not susceptible to self-cal. From observations of strong planets before and after it was observed that the amplitude scale was reasonably stable, and certainly more stable than implied by the phase-calibrator data, so that only phase calibration really needs to be applied to the source. This program allows the amplitude scale to be forced to the desired values (in this case, obtained from the planet observations) without changing the phase calibration.

This routine is specific to CARMA, hardcoded for 15 antennae.  


The input visibility file, containing the gain file to list/massage
amp List the amplitude gains: default option
         The mean, median and rms (about the mean) are reported.
phase List the phase corrections. complex List complex gains for 10 antennas only (2 lines per soln) all List all complex gains (one line per antenna per solution
         for all antennas; lots of output, better than
         options=complex if you want to grep one one antenna.)
replace Replace the amplitude gains with the list supplied
         Unless OPTIONS=FORCE is also set, only antennas with 
         non-zero values in the list are affected
         so if jyperk is not set, nothing happens. Phases are
         preserved unless options=zerophas is also specified
force If set, then all values in jyperk are enforced when
         doing a replace, even if they (or the initial gains)
         are zero
limit Impose an upper limit on the amplitude gains using the
         list specified in jyperk
multiply Multiply existing sqrt(Jy/K) values in a gains table by
         the list supplied in the jyperk variable. Only antennas
         corresponding to nonzero jyperk elements are changed.
         No effect on phases.
zerophas Zero all phase corrections (no antenna selection method) addphase Correct gains by antenna based phases supplied in the
         jyperk array, units degrees. Note that these phases
         are added to the existing phase gains, except when 
         OPTIONS=ZEROPHAS is also used.
clip Set to zero all gains outside range jyperk(1),jyperk(2)
         Useful for pseudo-flagging of bad data, e.g.,
         gplist vis=dummy options=clip jyperk=0.5,2.0
         effectively flags data with gains outside 0.5-2 (default 
         range). However, data are not really flagged. The next
         option is an alternative "flagging" option.
sigclip Set to zero all gains more than jyperk(1)*rms away from
         median on each antenna

Use options=replace,zerophas with suitable jyperk list to both set amp scale and zero phases (the two steps are carried out sequentially with the amplitudes being set first)

Use options=addphase to add phases to the existing ones.

Use options=addphase,force to replace phases.

If given, this is the list of ants you want to see displayed. Useful if you want a less wide screen display. By default all are displayed, within limits.
Array of 15 numbers (1 per antenna) giving the Jy-per-K values. Array elements default to zero so you don't have to give 15 numbers. Action will only be taken for antennas corresponding to nonzero elements of jyperk. Used for options=replace or options=multiply. For options=replace, if any of the numbers are zero then the amp gains in the pre-existing table will not be changed, so you can change the gains on a single antennna without changing the others by setting all the other values to zero. However, be aware that your one bad antenna will have affected the solutions for the other antennas as well. For options=multiply, jyperk supplies a list of multiplication factors (one per antenna) which will be used to multiply the sqrt(Jy/K) amplitude gains in the existing table.




This document was created by man2html, using the manual pages.
Time: 18:35:38 GMT, July 05, 2011