[daip] Pbcor

[Marina Kounkel]

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.

Marina


On Thu, Jan 17, 2013 at 7:01 PM, Eric Greisen <egreisen at nrao.edu> wrote:

> Marina Alexandrovna Kounkel wrote:
>
>> Hello,
>>
>> We are producing 4 fields for each object using imagr. Then we are trying
>> to use pbcor to correct photometry for the primary beam, however, it treats
>> each quadrant as an individual image while doing so. If we were to
>> explicitly specify observed ra and dec of the pointing center within the
>> header of the image, pbcor works fine, but as it is, this information
>> appears to be missing. What exactly should we do?
>>
>
> The pointing position should not be missing from image headers.  Where did
> these images come from and I suspect I may even need to know when?
> We are trying to carry the pointing position around carefully now but this
> was treated badly in the past.  The code in IMAGR certainly tries to copy
> the pointing position from the UV file to the image.  But I remain a bit
> uncertain about whether this all works.
>
> Note that you can use PUTHEAD to correct the headers (try GETHEAD to see
> what is in the parameters before you do).  IMHEADER will show a pointing
> position only if it is not the reference position (and not 0,0).
>
> Eric Greisen
>
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