CHECK AND ANALYSE UV VARIABLES

Miriad task smacheck can be used to check, analyse uv variables for SMA data and flag uv-data if variables or data are out of range. Here is an exmaple to check the variable systemp, give a report on simple statistical analysis, and flag the uv data if systemp is outside of the range specified.

  Task:   smacheck
  vis      = gc_rx1.lsb
  flagval  = flag
  var      = systemp
  range    = 1,1200
  options  = histo

The MIR data taken from the SMA online system essentially stores all the interferometer data including the data from the iPointing. The calibrator used for iPointing might be the same as that for the antenna gain calibration. It would be wise to flag the iPointing data. By default the integration time for iPointing is 5 sec. If the integration time used for normal scans differs from 5 sec, say 10 sec, then it is convenient to use smacheck to flag the iPointing scans:

  Task:   smacheck
  vis      = uvtest_rx1.lsb
  flagval  = flag
  var      = inttime
  range    = 7,15

In the case of polarization observations, MIR data might also contain non-polarization data (ipol=0), in addition to the four polarization components. smalod loads every data point from MIR data by converting MIR polarization state label (ipol) to the Miriad convention and retaining the non-polarization data unchanged. The non-polarization data might cause problem to the polarization calibration process in Miriad and needs to be flagged. For the circular polarization case, smacheck can gracefully flag the non-polarization data:

  Task:   smacheck
  vis      = uvtest_rx1.lsb
  flagval  = flag
  options  = circular