[daip] [!4910]: aips - DBCON

[Lynn D Matthews]

Lynn D Matthews updated #4910
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DBCON
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           Ticket ID: 4910
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/4910
           Full Name: Lynn D Matthews
               Email: lmatthew at haystack.mit.edu
             Creator: User
          Department: AIPS Data Processing
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template Group: Default
             Created: 12 May 2014 07:08 PM
             Updated: 12 May 2014 07:08 PM
                 Due: 14 May 2014 07:08 PM (2d 0h 0m)
      Resolution Due: 20 May 2014 07:08 PM (8d 0h 0m)



I have noticed a couple of issues with DBCON.

First, it gets confused if FQCENT=0 and the reference pixel of the input data is 1.0. In the case of two continuum datasets where the header frequencies are identical, it complains:

FREQUENCIES DIFFER BY TOO MUCH:  4.33440000D+10  4.32800000D+10
MULTI-FREQUENCY DATA BASES INCOMPATABLE

(Actually, the first frequency listed is what it should be at the band center, while the second one is the input file's value at the reference pixel).

For spectral line data, where the frequencies at the reference pixel are actually slightly different, it simply complains:
MULTI-FREQUENCY DATA BASES INCOMPATABLE

These errors messaged are eliminated if one sets FQCENT=1. However, in that case, it reports that it is using the same scaling factor for the two data sets. Shouldn't these be different?

For example, it says:
DBCON1: Scaling u,v,w of data set 2 by  1.0000881E+00
DBCON1: Scaling u,v,w of data set 1 by  1.0000881E+00

While the respective headers show the following:
Input Header 1:
FREQ       128   1.4192776E+09       1.00  1.9531250E+03    0.00
Input Header 2:
FREQ       128   1.4192149E+09       1.00  1.9531250E+03    0.00
Output header:
FREQ       128   1.4194026E+09      65.00  1.9531250E+03    0.00

So I would expect scaling factors of 1.0000881 and 1.0001323.

Thanks,
Lynn Matthews




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