1934-638 Calibration Issue

Got a calibration problem? Discuss it here.

Moderator: Mark.Wieringa

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julie
Posts: 12
Joined: Tue Mar 22, 2011 2:53 pm

1934-638 Calibration Issue

Post by julie »

I am calibrating some CABB data from 2009 (500 MHz band) and I seem to have stumbled onto something odd. Below I have plotted the baseline pairs as a function of time and amplitude. The data is from IF2 (IF1 looks the same) and of XX (YY looks similar). The data is not averaged in frequency. This data has not been bandpass calibrated, only the calibration at the time of the observations was completed.

Couple of questions:

1. Has anyone ever seen something like this before?
2. What would cause this?
3. I'm assuming that this data is garbage. Or does anyone know how to fix this?

Cheers,
Julie
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Mark.Wieringa
ATCA Expert
Posts: 297
Joined: Mon Feb 08, 2010 1:37 pm

Re: 1934-638 Calibration Issue

Post by Mark.Wieringa »

Hi Julie,

Since the observation is in the 1.7 GHz area, I would first suspect interference.
Try making a uvspec plot of the same data and see if the bad stuff is concentrated in a few channels.
Alternatively, reload the data with options=birdie,rfiflag in atlod and see if that improves things.

Cheers,

Mark
julie
Posts: 12
Joined: Tue Mar 22, 2011 2:53 pm

Re: 1934-638 Calibration Issue

Post by julie »

Hi Mark,

I ran uvpsec to look at the data and found something odd at the beginning of the 1934-638 scan. I don't think that this is RFI and maybe why I missed it before when I loaded the data with options=birdie,rfiflag in atlod. I flagged it out and we are back up and running. Thank you!

Cheers,
Julie
uvspec1.png
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