[daip] New Client Reply - [!VFT-650742]: EVLA Data In AIPS

[John Michael Cannon]

New Client Reply: EVLA Data In AIPS

I have now attempted to calibrate the program 10B-187 data obtained on June 22 without applying FRING and without spectrally averaging via SPECR, and have had no success.  The poor phases remain in the final solutions.  I include my work log as a pdf attachment, showing inputs to the various task for one calibration attempt, if they are useful.  

I executed SPFLG on all sources prior to BPASS.  Some minor RFI was apparent on short baselines and was excised, but I would not deem it to be particularly serious.  A few strange effects were present in the data, however, that I have not seen before:

1.  A wavy pattern of amplitude vs. time in a given channel (see images of baselines 5-15 and 8-27 in the PDF file, showing screenshots of SPFLG amplitude displays on baselines 5-15 and 8-27 in RR) on the primary calibrator.  Almost all antenna 5 RR baselines have this effect & I simply flagged that antenna/stokes completely; other antennas show it on some baselines but not others (e.g., antenna 23 in LL).   This does not appear in weaker sources (phase cal, source).

2.  Antenna 2, LL stokes, all sources, shows a pattern of obviously high amplitudes at all times on every 32nd channel.  The image of baseline 2-26 shows the SPFLG display of amplitude for LL stokes on baseline 2-26.  I simply flagged those 8 channels (33, 65, 97, 129, 161, 193, 225, 256).

Returning to the issue of calibrating the data, I have tried both suggestions in Appendix E of the AIPS Cookbook (page E-6) to modify the execution of BPASS.  The differences between the two techniques was negligible.

A summer student of mine has tried the same approach with the data obtained on June 12 and finds the same unacceptable CALIB solutions.  He also finds the same data symptoms described above. 

Do you have any further suggestions to calibrate these data?  In the meantime I am attempting another calibration solution, applying SPECR. 

Thanks for your help,
John

Ticket Details
===================
Ticket ID: VFT-650742
Department: AIPS Data Processing
Priority: Default
Status: Open
Link:  https://help.nrao.edu/staff/index.php?_m=tickets&_a=viewticket&ticketid=321
-------------- next part --------------
A non-text attachment was scrubbed...
Name: cannon.july21.pdf
Type: application/pdf
Size: 646440 bytes
Desc: not available
URL: <http://listmgr.nrao.edu/pipermail/daip/attachments/20100721/69c91bab/attachment.pdf>