[daip] New Ticket - [!BAD-905454]: problem with DBCON output

[Lynn D Matthews]

New Ticket: problem with DBCON output

I have been encountering some unexpected behavior in the results from
DBCON.

I have loaded into AIPS three MWA data sets with the same center
frequency. After running UVSRT on all three, I attempt to combine them
with DBCON.

The first two times I ran DBCON (i.e., to create 1+2 and 1+2+3), I got the
following messages:

MWA1  > DBCON1: Task DBCON  (release of 31DEC10) begins
MWA1  > DBCON1: Scaling u,v,w of data set 2 by  9.1752577E-01
MWA1  > DBCON1: Scaling u,v,w of data set 1 by  9.1752577E-01
MWA1  > DBCON1: RA DOES NOT MATCH, BUT NOT DOING SHIFTS!
MWA1  > DBCON1: DEC DOES NOT MATCH, BUT NOT DOING SHIFTS!
MWA1  > DBCON1: Create 3/27 1+2 R  .DBCON .   1 (UV)  on disk  1  cno  125
MWA1  > DBCON1: ANREFM: NO ANTENNA OR ARRAY RECOGNIZED
MWA1  > DBCON1: ANREFM: NO ANTENNA OR ARRAY RECOGNIZED
MWA1  > DBCON1: Consolidate AN files from vol/cno/vers  1 122  1 and  1 123  1
MWA1  > DBCON1: Appears to have ended successfully
MWA1  > DBCON1: mwa1 31DEC10 TST: Cpu=     31.7  Real=    490  IO=     12825
MWA1  > DBCON1: Task DBCON  (release of 31DEC10) begins
MWA1  > DBCON1: Scaling u,v,w of data set 2 by  9.1752577E-01
MWA1  > DBCON1: RA DOES NOT MATCH, BUT NOT DOING SHIFTS!
MWA1  > DBCON1: DEC DOES NOT MATCH, BUT NOT DOING SHIFTS!
MWA1  > DBCON1: Create 3/27 1+2+3R .DBCON .   1 (UV)  on disk  1  cno  126
MWA1  > DBCON1: ANREFM: NO ANTENNA OR ARRAY RECOGNIZED
MWA1  > DBCON1: ANREFM: NO ANTENNA OR ARRAY RECOGNIZED
MWA1  > DBCON1: DBANT: AN headers may be incompatible for version    1
MWA1  > DBCON1: Consolidate AN files from vol/cno/vers  1 125  1 and  1 124  1

If I then use UVPLT to plot u vs. v for one second of data from the
original UVSRT file and compare this with the same plot from the DBCON
file, there is a clear offset between the two (screen shot attached).

Comparing the antenna table of the UVSRT file vs. DBCON files, 
I see that the former lists Freq=   186.240000 MHz (which is the
frequency at the band center), while the latter lists Freq=
170.880000 MHz (the frequency of channel 1).

What puzzles me the most, is that if I now run DBCON again on my
original UVSRT files, it behaves differently; the messages are now as
follows:

MWA1  > DBCON1: Task DBCON  (release of 31DEC10) begins
MWA1  > DBCON1: RA DOES NOT MATCH, BUT NOT DOING SHIFTS!
MWA1  > DBCON1: DEC DOES NOT MATCH, BUT NOT DOING SHIFTS!
MWA1  > DBCON1: Create JUNK 1+2    .DBCON .   1 (UV)  on disk  1  cno  127
MWA1  > DBCON1: ANREFM: NO ANTENNA OR ARRAY RECOGNIZED
MWA1  > DBCON1: ANREFM: NO ANTENNA OR ARRAY RECOGNIZED
MWA1  > DBCON1: Consolidate AN files from vol/cno/vers  1 122  1 and  1 123  1
MWA1  > DBCON1: Appears to have ended successfully
MWA1  > DBCON1: mwa1 31DEC10 TST: Cpu=     31.1  Real=    415  IO=
12825
MWA1  > DBCON1: Task DBCON  (release of 31DEC10) begins
MWA1  > DBCON1: RA DOES NOT MATCH, BUT NOT DOING SHIFTS!
MWA1  > DBCON1: DEC DOES NOT MATCH, BUT NOT DOING SHIFTS!
MWA1  > DBCON1: Create JUNK 1+2+3  .DBCON .   1 (UV)  on disk  1  cno  128
MWA1  > DBCON1: ANREFM: NO ANTENNA OR ARRAY RECOGNIZED
MWA1  > DBCON1: ANREFM: NO ANTENNA OR ARRAY RECOGNIZED
MWA1  > DBCON1: Consolidate AN files from vol/cno/vers  1 127  1 and  1 124  1
MWA1  > DBCON1: Appears to have ended successfully
MWA1  > DBCON1: mwa1 31DEC10 TST: Cpu=     48.3  Real=    650  IO=     19255

This time, there are no u-v offsets between the original and DBCON
files, and the frequency in the resulting antenna table is the same as in the
original data (186.240000 MHz).  

I encountered the same behavior a week ago and thought it must be
pilot error, but this time I can readily trace back my steps and
cannot see an obvious mistake. Thanks in advance for any insights you can offer.

Lynn Matthews

Ticket Details
===================
Ticket ID: BAD-905454
Department: AIPS Data Processing
Priority: Default
Status: Open
Link:  https://help.nrao.edu/staff/index.php?_m=tickets&_a=viewticket&ticketid=294
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