[daip] question about SN table from CALIB

[Eric Greisen]

Tony Wong writes:

 > My student and I are reducing some data from the VLA archive, taken around
 > 1986.  We find that when running CALIB with the following inputs:
 > 
 >     inname 'N891-C'
 >     inclass 'CH 0'
 >     inseq 1
 >     calsour '3C84',''
 >     refant 16
 >     weightit 1
 >     solmode 'A&P'
 >     cparm(5) 1
 >     snver 1
 > 
 > followed by LISTR with optype 'gain', that the gain table has several
 > entries for the source (N891) in addition to the calibrator.  However, not
 > every source observation has an entry (see attached log).  We find this
 > puzzling.  After a GETJY (with sources='3c84', calsour='3c286') to scale the
 > gains on 3C84 by the right factor, the gains on N891 remain unscaled, as is
 > obvious from doing an SNPLT.  It's not clear that our calibration has been
 > adversely affected, but we wanted to make sure this is expected behavior.
 > 
I do not think that things are correct here.  N891 appears in the CL
table but not the SN table unless you ran CALIB with N891 as a
calibrator.  SN tables contain only calibration sources.  Note that
SNPLT will plot either of these tables (and TY etc).  After GETJY you
clearly were looking at the CL table not SN - after that ???  To get
the data from the SN table after CALIBs and GETJY you must run CLCAL.

Note too that when you specify SNVER to CALIB, it appens its latest
output to that SN table.  This may well not be what you want.  CLCAL
will gather up the SN tables that you need into one before applying
the result to the CL table.

Eric Greisen