[daip] Pbcor

[Eric Greisen]

On 1/17/2013 9:00 PM, Marina Kounkel wrote:
> This is EVLA data observed July and August 2011 in three epochs.
>
> None of the keywords for GETHEAD that I tried return anything. Not 
> even something as simple as IMNAME, not to mention OBSRA or OBSDEC. 
> This works on neither the original UV file nor on IBM/ICL images.
>
> Interestingly enough, though, if I use IMHEADER in UV image, then 
> there is this:
> RA           1    00 00 00.000 1.00       3600.000    0.00
> DEC          1    00 00 00.000 1.00       3600.000    0.00
>
> Same thing in the quadrant produced by IMAGR lists actual ra and dec 
> for the central pixel of each quadrant.
>
> When these data were worked on this summer, there was no problem in 
> this regard, whether it was by default and something has changed since 
> then, or through some sort of command that was forgotten to be recorded.
>

Did you load these data with BDF2AIPS or through the archive?

I am suspecting that we now have a problem with the pointing position
- my latest data came through BDF2AIPS and the new-format SU file lists 0.0
for the pointing position.

GETHEAD should work fine:
    keyw='crval1'; geth;
should show the RA in degrees at the reference pixel in KEYVAL.

You can do PUTHEAD for OBSRA and OBSDEC (both in degrees).

Multi-source UV data shows what you list above in the UV header since
in fact multiple RAs and Decs are in the file.  Single-source UV data will
have the correct RA and Dec in the header and should have the OBS position
in the header too.  I think there is a bug for me to fix here - but you need
to do the work-around of putting the obs position in each header.

Eric Greisen