[Difx-users] How to read difx2fits output

[Rebecca Lin]

Hi Adam and Harro,

Adam: It may be useful to take a look at your  fits_compare.py script if
it's not too much trouble for you to put it on github. I can try to see if
it works with the helper functions.

Harro: Thanks, I'll give this a try!

Cheers,
  Rebecca


On Sun, 29 Aug 2021 at 08:23, harro verkouter <hverkouter at gmail.com> wrote:

> Hi all,
>
> For the verification of sfxc postprocessingtools (to generate e.g.
> FITS-IDI files) we have a comparisontool for the meta-data. The one for
> numerical equivalence of two FITS-IDI files is currently lacking (it does
> work for MeasurementSets):
>
> https://code.jive.eu/verkout/jive-toolchain-verify
>
> Specifically look at the ‘compare-ms-idi-meta.py’ script. Despite it’s
> name it can compare any number of FITS-IDI and/or MeasurementSet files -
> including zero of either 😄
>
> Cheers,
> h
>
> Op zo 29 aug. 2021 om 10:17 schreef Adam Deller via Difx-users <
> difx-users at listmgr.nrao.edu>
>
>> Hi Rebecca,
>>
>> I have a script called fits_compare.py that diff's two FITS-IDI files
>> that are supposed to be identical (i.e., same antennas, integration time,
>> etc).  It was always a bit of hack/check code and is probably not very user
>> friendly.  If you want I can put it on github so you can get it - it also
>> has a dependency on some helper functions that are available in
>> https://github.com/dingswin/psrvlbireduce/, but there's every chance
>> that it won't work out of the box and I don't have any time to debug it at
>> the moment.  But let me know if you'd like me to make it available and try
>> investigating it.
>>
>> Cheers,
>> Adam
>>
>> On Sun, 29 Aug 2021 at 07:57, Rebecca Lin via Difx-users <
>> difx-users at listmgr.nrao.edu> wrote:
>>
>>> Hi Leonid,
>>>
>>> Thanks for pointing me to the documentation! I'm hoping to compare
>>> visibilities from my correlation pipeline to the output from DiFX.
>>>
>>> Best,
>>>   Rebecca
>>>
>>> On Sat, 28 Aug 2021 at 13:16, Leonid Petrov <Leonid.Petrov at lpetrov.net>
>>> wrote:
>>>
>>>> Rebeca,
>>>>
>>>> > I'm wondering if there is documentation on how information is stored
>>>> in the
>>>> > fits file
>>>>
>>>>   Sure:
>>>>
>>>> ftp://ftp.aoc.nrao.edu/pub/software/aips/TEXT/PUBL/AIPSMEM114.PDF
>>>>
>>>> > and how to plot the visibilities.
>>>>
>>>>   Usually, these plots are useless. There are exceptions, but generally,
>>>> you need process the data first to see any signal. You can develop your
>>>> own software for visibility analysis or try to use existing packages,
>>>> whichever you prefer. But it is not easy. Depending on the problem,
>>>> mastering data analysis may take from months (though this sounds
>>>> very optimistic) till ... all your life. Good luck.
>>>>
>>>> > I'm mainly wondering where the
>>>> > complex visibilities are stored in the fits file.
>>>>
>>>>   In section UV_DATA. See AIPSMEM114.PDF for details.
>>>>
>>>> Leonid
>>>> 2021.08.28_13:09:41
>>>>
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>>>
>>
>>
>> --
>> !=============================================================!
>> A/Prof. Adam Deller
>> ARC Future Fellow
>> Centre for Astrophysics & Supercomputing
>> Swinburne University of Technology
>> John St, Hawthorn VIC 3122 Australia
>> phone: +61 3 9214 5307
>> fax: +61 3 9214 8797
>>
>> office days (usually): Mon-Thu
>> !=============================================================!
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>
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