[daip] Calibration

[Eric Greisen]

Johan van der Walt writes:
 > In the AIPS Cookbook on p 4-14: Paragraph starting with "If the
 > secondary calibrators ...."
 > 
 > Are secondary and phase calibrators the same thing? My observing run
 > had the following sequence:
 > 
 > 1331+305
 > 
 > Cal1
 > Program source 1
 > Cal1
 > Cal2
 > Program Source 2
 > Cal2
 > etc.
 > 
 > Do I have to run CALIB also on Cal1, Cal2 etc before running GETJY?
 > 
 > Also does section 4.4 refer to the editing of Cal1, Cal2 etc?
 > 
 > Thanks
 > 
 > Johan
 > 
 > Due to an unfortunate event I lost all my AIPS data on disk and had
 > to start all over again! - from there the question.
 > 
 > 

Primary calibrators are ones like 3C286 for which one has a good guess
as to the flux.  Secondary ones are those for which one does not
necessarily know the flux.  You need to run CALIB on all cal sources
before running GETJY so that GETJY will have both some real fluxes
(from SETJY on primary cal sources) and all pseudo fluxes that it will
need to fit and correct.

Sec 4.4 refers primarily to your cal sources since you know aht they
should look like - e.g. after cal the same flux on each baseline, all
phases near zero.  Editing of the unknown source comes partly from
things like ant 6 LL is bad in 2 consecutive cal scans so it must be
bad in between on the source.  If your program sources have lots of
structure then you do not know what to expect for them other than
upper limits to fluxes and the like - one can edit on that now or
later in the self-cal (if appropriate) stage .

ERic Greisen