[daip] Assistance with Flagging Issues in AIPS {External}

[Eric Greisen]

It is a long holiday weekend for us so it will be until next week for me to look more deeply into this.  When I have TY table troubles I use TYSMO to replace the bad TY values with good ones and then use the new TY table in the calibration.

Eric Greisen


________________________________
From: Daip <daip-bounces at listmgr.nrao.edu> on behalf of Lieuwe de Regt via Daip <daip at listmgr.nrao.edu>
Sent: Thursday, November 28, 2024 7:18 AM
To: daip <daip at nrao.edu>
Cc: Pikky Atri <atri at astron.nl>
Subject: [daip] Assistance with Flagging Issues in AIPS {External}

Dear designated AIP,

I am a PhD student at ASTRON and Radboud University, working with my supervisor, Dr. Pikky Atri (cc’ed), on reducing VLBA data using AIPS. However, I’ve encountered some issues related to flagging, and I would appreciate your advice.

In my data, there are sudden variations in the system temperature, which I have flagged using UVFLG (see figure BM500_SystemTemperatureSpikes.png in the attachments).
When I run the task VLBAAMP, the output indicates that the subtask ACSCL is using the FG table I created. However, upon examining the CL table with the gain corrections produced by VLBAAMP, it does not seem like any areas have been flagged, i.e., the flagged spikes still persist (see figure BM500_PersistentAmplitudeSpikes in the attachments).

To circumvent this, I attempted to flag the TY table directly using SNEDT. This created a new version of the TY table with the flagged areas removed. However, running VLBAAMP again results in the same outcome, with the flagged areas seemingly not being applied.

At this point, the only way forward I can see is to flag the CL table produced by VLBAAMP. However, this would mean the sudden variations in system temperature would have already influenced the amplitude calibration, which is not ideal.

Am I missing something in the procedure, or could this be a potential issue in AIPS?

Thank you for your time and for maintaining AIPS!

Kind regards,
Lieuwe de Regt


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