[daip] UVSUB: Subtracting all the Stokes contributed by point sources from the UV data

[Eric Greisen]

Wasim Raja wrote:
> Dear Eric
>   In continuation to my query below:
>   Does UVSUB do something to the ANTENNA-BASELINE
>   Numbering scheme? I get this error (last line in the output
>   below) when I try to load the FITTP-ed AIPS UVSUB data
>   into MIRIAD:
>   [The AIPS version I am working on is 31DEC10]
> 
>  >Fits: version 1.1 09-Feb-07
>  >### Warning:  Unable to guess typical system temperature
>  >### Warning:  Unable to guess typical system gain
>  >Assuming feed angle is 0 degrees
>  >### Warning:  Insufficient information to determine parallactic angle
>  >Reading AIPS AN table
>  >Decrementing times for configuration  1 by 33.0 seconds (IAT-UTC).
>  >Reading AIPS FQ table
>  >Data are circularly polarized
>  >Reading the correlation data
>  >### Fatal Error:  Illegal baseline number in antbas
> 
> thanks
> --wasim
> 
> On Tue, Aug 16, 2011 at 3:28 AM, Wasim Raja <wasimraja81 at gmail.com 
> <mailto:wasimraja81 at gmail.com>> wrote:
> 
> 
>     Dear Eric,
>       I wish to subtract from the UVDATA the contributions in all the
>       Stokes from a point source at the center of the field observed, so
>       that when I image the residual, I see the diffused emission.
> 
>       Using UVSUB seemed to me to be the right task. However it
>       seems to provide me a handle only on Stokes-I. What should I
>       use for the other Stokes?

The Miriad messages are curious.  UVSUB will not change the 
antenna/baseline indications.  The assumption that the feeds are linear 
before reading the antenna table is curious.  Is this VLA data or EVLA?
The subtraction of 33 sec to go from IAT to UTC would not be correct for 
EVLA data.

It would be convenient if the error message said what it took to be 
illegal...

I would be concerned that the FTP did not work correctly - did you say 
binary before the transfer?

Eric Greisen