[daip] [!7751]: AIPS - AIPS does not correctly recognize the unit of fits keyword BUNIT produced with CASA

[Misato Fukagawa]

Misato Fukagawa updated #7751
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AIPS does not correctly recognize the unit of fits keyword BUNIT produced with CASA
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           Ticket ID: 7751
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/7751
           Full Name: Misato Fukagawa
               Email: misato.fukagawa at nao.ac.jp
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template Group: Default
             Created: 21 December 2015 09:49 AM
             Updated: 21 December 2015 09:49 AM
                 Due: 23 December 2015 09:49 AM (2d 0h 0m)
      Resolution Due: 30 December 2015 09:49 AM (9d 0h 0m)



Dear AIPS helpdesk, 

I would like to forward a user's report below on the issue related to the header keyword BUNIT, 
which we received at ALMA helpdesk. 
A fits file created with CASA 'exportfits' has a BUNIT with a unit of 'Jy/beam' with >=CASA 4.3, 
while 'JY/BEAM' with CASA 4.2 and earlier. This change was made since 'JY/BEAM' is not correct 
according to the FITS standard and caused problems in other tools (CAS-6551). Unfortunately, 
this improvement caused an issue with the AIPS task as reported by the user. 

Could you see if you can fix the problem in AIPS? 

Best regards,
Misato Fukagawa (ALMA helpdesk in EA ARC)

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Dear ARC members and CASA (AIPS) developers, 

I made a image cube data by the CASA task clean and the data was exported in the fits format by using the CASA task exportfits. 
The fits file was loaded to my AIPS 13DEC13 version to plot spectra by the AIPS task ISPEC (with optype='flux' to show flux density). 
When I used the fits file from the CASA version 4.2.30986, the ISPEC showed the flux density in unit of Jy. 
It was consistent with the flux density measured in the spectral profile tool of the CASA viewer. 
However, when I used the fits file from the CASA version 4.4.0 and 4.5.0, the ISPEC showed the intensity in unit of Jy/beam. 
This value seemed to be consistent with the Sum in the spectral profile tool of the CASA viewer. 

I checked the fits files and found that the header information were different between 4.2.30986 and 4.4.0/4.5.0. 
The BUNIT in the fits files were JY/BEAM and Jy/beam for the 4.2.30986 and 4.4.0/4.5.0 versions, respectively. 
To solve this problem, I run the AIPS verb PUTHEAD with keyword='BUINIT' and keystrng='JY/BEAM'. 
After the PUTHEAD command, the ISPEC showed the correct flux density in unit of JY. 

It this a bug in the CASA exportfits or the AIPS ISPEC? 
Or is it a correct operation?

Thank you for your suggestion. 

Best regards, 
Tomoya

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