[daip] [!11645]: AIPS - Help with AIPS TYAPL, TYSMO and SY-table values:

[Michael Bietenholz]

Michael Bietenholz updated #11645
---------------------------------

Help with AIPS TYAPL, TYSMO and SY-table values:
------------------------------------------------

           Ticket ID: 11645
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/11645
                Name: Michael Bietenholz
       Email address: mbieten at yorku.ca
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template group: Default
             Created: 08 February 2018 04:39 PM
             Updated: 08 February 2018 04:39 PM
           Reply due: 12 February 2018 04:39 PM (4d 0h 0m)
      Resolution due: 04 November 2020 12:00 AM (999d 7h 21m)

I'm just wondering about the use of AIPS TYSMO, and EVLA Psum, Pdif and Tsysvalues (SY-table) which I have little experience with.I'm looking at P-band data 14-DEC-2014 (14B-373). Now I'm observing the Crab, so I expect the source to raise the system temperatures, but that should cause high but not variable Tsys. I loaded the data into AIPS using BDF2AIPS (31DEC18; obit-1.1.500-1-64b). I gather that I should apply gains derived from the SY table using TYAPL, optype 'PGN'. However looking at the Tsys values makes me think I should edit / smooth them first.The TSYS (PSYS) values in the SY table are pretty wildly variable - I attach an example plot from SNPLT: psys-1.png, showing "PSYS" for antennas 1-4, poln=X, all IFs (spw). Antenna 1 has many extremely high values (>1 MegaK) across many IFs and there are sporadic high values in other antennas mostly confined to a few IFs.Zooming in to the above by plotting only values <1000K, I get psys_2.png - concentration of values around 200-600K (except for antenna 1), but quite noisy especially in some IFs (although it doesn't seem to be the RFI-dominated IFs)Zooming in in time, I have psys-3.png, which shows short (~2min) excursions up to ~2000 K for antenna 4,5 in IF16 (472 MHz dark blue).I further attach psum.png - scaled so that sporadic high values up to ~50000 counts are not visible, but more systematic structure is. Also, pdif.png: again, sporadic outliers between ~-1000 and + 1500 counts or off the plot.Finally, there is something very non-random going on in psys-dual.png, psum-dual.png and pdif-dual.png These show only 5mins of data X-pol, IF15. There are periodic, every ~10s, values that are systematically different - even though this is all one source. I see the same pattern over much of run, so its not just over these 5 mins.It loooks like some kind of median filter on fairly short (say 30-sec) timescales is called for. Should I edit out excursions such as seen in psys_3.png? Should I just radically clip SY values antenna 1 (or just throw it out)? Any idea what is going on with the ~10-s periodicity? Any experience with APARM,CPARM values to use for TYSMO? When should I edit out visibility data?

------------------------------------------------------
Staff CP:  https://help.nrao.edu/staff
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listmgr.nrao.edu/pipermail/daip/attachments/20180208/b248ede5/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: psys-1.png
Type: image/png
Size: 46072 bytes
Desc: not available
URL: <http://listmgr.nrao.edu/pipermail/daip/attachments/20180208/b248ede5/attachment-0008.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: psys-2.png
Type: image/png
Size: 134616 bytes
Desc: not available
URL: <http://listmgr.nrao.edu/pipermail/daip/attachments/20180208/b248ede5/attachment-0009.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: psys-3.png
Type: image/png
Size: 80933 bytes
Desc: not available
URL: <http://listmgr.nrao.edu/pipermail/daip/attachments/20180208/b248ede5/attachment-0010.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: psum.png
Type: image/png
Size: 37462 bytes
Desc: not available
URL: <http://listmgr.nrao.edu/pipermail/daip/attachments/20180208/b248ede5/attachment-0011.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pdif.png
Type: image/png
Size: 117518 bytes
Desc: not available
URL: <http://listmgr.nrao.edu/pipermail/daip/attachments/20180208/b248ede5/attachment-0012.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: psys-dual.png
Type: image/png
Size: 24920 bytes
Desc: not available
URL: <http://listmgr.nrao.edu/pipermail/daip/attachments/20180208/b248ede5/attachment-0013.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: psum-dual.png
Type: image/png
Size: 15391 bytes
Desc: not available
URL: <http://listmgr.nrao.edu/pipermail/daip/attachments/20180208/b248ede5/attachment-0014.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pdif-dual.png
Type: image/png
Size: 18300 bytes
Desc: not available
URL: <http://listmgr.nrao.edu/pipermail/daip/attachments/20180208/b248ede5/attachment-0015.png>