[daip] [!8340]: AIPS - wrong RDBE Tsys for BC204A, HN: what can be done?

[Yuri Kovalev]

Yuri Kovalev updated #8340
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wrong RDBE Tsys for BC204A, HN: what can be done?
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           Ticket ID: 8340
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/8340
           Full Name: Yuri Kovalev
               Email: yyk at asc.rssi.ru
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template Group: Default
             Created: 03 May 2016 10:32 AM
             Updated: 03 May 2016 10:32 AM
                 Due: 05 May 2016 10:32 AM (2d 0h 0m)
      Resolution Due: 11 May 2016 10:32 AM (8d 0h 0m)



Dear colleagues,

I am taking about the following experiment: http://www.vlba.nrao.edu/astro/VOBS/astronomy/dec13/bc204a/

If you take a look at RDBE Tsys values which I must use for data processing, you will realize that there are issues with the last several hours of HN: http://www.vlba.nrao.edu/astro/VOBS/astronomy/dec13/bc204a/MARK5C/jobs/tsys -- the Tsys values become negative.
For your convenience, I attach an AIPS printout of Tsys values taken from the FITS IDI file (TY table) of the correlator output for this experiment.

One can see in the logs of the experiment: 
2009-2101 *HN out. converting pack from mk5a to mk5c.            TAPE   100   52

After this, the HN Tsys became negative for the last 5 hours of the experiment.

It seems to me that the HN Tsys values make sense if one simply makes them positive.
I do not want to lose 5 hours of HN if data are OK.

Here come my questions:
1. Do you have an idea, why did HN Tsys values became negative?
2. Does it mean that HN data are bad for the last 5 hours of this experiment?
3. If the HN data are fine and the only thing which I need to do is to change Tsys values from negative to positive, what is the best way to do it in AIPS?

Cheers,
Yuri

P.S. Sorry that I have accidentally clicked the Submit button and generated a bogus ticket some minutes ago. I have marked it as closed since I did not find how to delete it.

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