[daip] [!9198]: AIPS - MULIF, add autocorrelations?

[Thomas Krichbaum]

Thomas Krichbaum updated #9198
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MULIF, add autocorrelations?
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           Ticket ID: 9198
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/9198
           Full Name: Thomas Krichbaum
               Email: tkrichbaum at mpifr-bonn.mpg.de
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template Group: Default
             Created: 25 October 2016 01:17 PM
             Updated: 25 October 2016 01:17 PM
                 Due: 27 October 2016 01:17 PM (2d 0h 0m)
      Resolution Due: 02 November 2016 01:17 PM (8d 0h 0m)



We need to combine two IDI-FITS files, which were created by DifX2FITS. Both files have different numbers of IF channels.
File1 has 8 IFs from the VLBA (2 Gbps, PFB mode ), File2 has only half of the bandwidth (1 GBps, 4 IFs, IF1 to IF4) from KVN.
The KVN observed with  half of the bandwidth, and its observing band is matching the lower half of that from the VLBA.
So IF1 to IF4 are matching between File1 and File2.
  
We need to expand File2 into a data file with 8 IFs, so that we can combined (DBCON) File1 and File2. 

We found the following work-around:
On File2 I run MULIF (NPOINTS=8) to change the number of IFs from 4 to 8. Then remove the frequency
table FQ1 created by MULIF and replace FQ1 using TACOP FQ1 from File1 to File2. Now both files have 8 IFs
and identical FQ tables, so DBCON can combine FILE1 and FILE2.

The disadvantage of this method is that MULIF most likely does not copy the autocorrelations into its output file, 
but only the cross-correlations (after MULIF the number of visibilities shown via IMHEAD is smaller). 
Therefore it is not possible to run ACCOR after MULIF.  I tried to run ACCOR before MULIF, but MULIF also does not copy
the SN (or CL) table over into the output file. 

Is it possible to make a fix, in which MULIF also copies the autocorrelation functions, so that after MULIF we
can run ACCOR ?
 
Or is there an alternative way to combine 2 UV-FITS  files in which in the 2nd file half of the IFs are missing ?
FITLD does not do this.

best regards,   Thomas 



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