[daip] Recent changes in DBCON seen in TST in Green Bank

[Bob Garwood]

Thanks.  Good to hear.

On April 20, 2015 3:36:25 PM EDT, Eric Greisen <egreisen at nrao.edu> wrote:
>On 04/15/2015 01:50 PM, Bob Garwood wrote:
>> Hi Eric,
>>
>> We've seen some changes in DBCON as used by the GBT pipeline in the
>TST
>> version.  These may indicate long standing mis-uses of pseudo-uvdata
>to
>> hold GBT data prior to gridding with SDGRD but at any rate, TST is
>> currently unusable by the GBT pipeline so we need to sort out what
>the
>> fix is before TST becomes NEW next year.
>>
>> We get calibrated GBT data into AIPS by converting SDFITS files to
>> random group/pseudo-uvdata using a program that Glen Langston wrote
>> called idlToSdfits (that we have the code for, but haven't done much
>> work inside it since Glen left NRAO).  For multi-beam data, we
>calibrate
>> the beams separately, producing a separate SDFITS file, and then a
>> separate uvfits file which we read into aips and then use DBCON in
>aips
>> to produce one data set to be used by SDGRD.  The DBCON step now
>fails
>> in the TST version of AIPS, producing either this message:
>>
>> DBCON1: UVPGET: RANDOM PARMS NOT ALL THERE:  0  1  0 -1  2 -1 -1 -1
>-1 -
>>          1 -1 -1
>>
>>
>> or this ...
>>
>> DBCON1: I CAN ONLY HANDLE STANDARD FORMS OF STOKES AXES
>>
>>
>> We believe both of these errors have to do with the STOKES axis,
>> depending on what idlToSdfits has done.
>>
>> In the first case, the input SDFITS files are all single polarization
>> and so the STOKES axis (which is the 3rd axis in the uvfits file) is
>just
>>     NAXIS3 =  1
>>     CRVAL3 = -1
>>     CRPIX3 =  1
>>     CDELT3 = -1
>>
>> And DBCON is being asked to combine 2 of those.
>>
>> In the second case, idlToSdfits has combined 2 polarizations so the
>> STOKES axis has 2 elements on it and looks like this:
>>     NAXIS3 = 2
>>     CRVAL3 = -1
>>     CRPIX3 = 1
>>     CDELT3 = -1
>>
>> Using "imh" in AIPS, the "uv" data files all reflect those values
>from
>> the original fits files.
>>
>> Any advice on how we should proceed (e.g. modifying the output of
>> idlToSdfits) would be appreciated.  Thanks.
>>
>> Bob
>
>
>A MNJ tomorrow will fix the DBCON issues.
>
>Eric
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