[daip] bad amplitude

[Leonia Kogan]

Hi Krzysztof,

I think the only explanation of the jump of your source flux at 31 Dec is snow.

I hope that 3C138 is the secondary calibrator at your experiment.
Otherwise it is difficult for me to explain the variability of the
primary calibrator.

The fluxes found by GETJY would be correct if the snow on the antennas 
has the same level during observation of the primary and secondary calibrators.
It looks like it is not true: the snow level was different.

>Could you advise me what to do, please?

You can apply for the repeat of the third stage of observation, if the delay 
of one year is OK for you.

Leonia
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>From chris at nac.oa.uj.edu.pl Mon Sep 23 06:54 MDT 2002
From: Krzysztof Chyzy <chris at oa.uj.edu.pl>
Subject: bad amplitude
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Dear Analyst,

I'm not sure if you have got my previous e-mail about some problems with
data reduction so I enclose it again below. I will appreciate
very much if you can help.

Best regards,

Krzysztof
-----------------------------------------------------------------
Forwarded message:
> From chris Sun Sep 15 15:49:16 2002
> Subject: bad amplitude
> To: analysts at nrao.edu
> Date: Sun, 15 Sep 2002 15:49:16 +0200 (CEST)
> X-Mailer: ELM [version 2.5 PL3]
> Content-Length: 2015      
> 
> Dear Analyst,
> 
> In our recent project AU88-01 we observed with the VLA D-config. 
> in C-band a dwarf galaxy IC10. Our study is mainly devoted to detailed
> polarization study of this BCG galaxy so we obtained 3 times
> 8h observing time on: 4 Dec 01, 28 Dec 01, 31 Dec 01 to make
> a sensitive search for regular magnetic fields.
> 
> The data quality from the first two days are acceptable, but I cannot
> properly calibrate the data from 31 Dec to have similar results to 
> the first 2 days. Some numbers to show possible error of the corruption 
> (the data were carefully inspected and flagged):
> 
>                  4 Dec      28 Dec     31 Dec
> 
> getjy task       3.74Jy    3.75Jy    8.18Jy 
> sour 3C138    
> 
> getjy task       1.14Jy    1.13Jy    2.04Jy
> sour 0059+581     
> (phase calibrator)
> 
> task edita       60-70A    60-70K    60-160(or -200)K - all antennas!
> range of Tsys
> 
> tvstat, IC10,    1.2e-5Jy  1.2e-5Jy  3.1e-4Jy
> rms in TP map
> 
> total flux       152mJy    150mJy    221mJy
> IC10                                 less extended
>                                      structure visible
> 
> The SN table (also TY) shows a gradual huge increase of the signal (amplitude) 
> from the beginning (31 Dec 2001 20:29) up to about the middle of the 
> observation (01 Jan 2002 00:30) and then similar decrease to the end of the 
> observing run (01 Jan 2002 04:28). From the observing log I know that it was 
> snowing and for a half of hour the operator was running the SNOW program to
> dump snow from dishes. 
> 
> Could you advise me what to do, please? At this stage the data from the
> third day is useless. What was the cause of this big rise and the fall down
> of the amplitude? The phase signal is O.K. 
> 
> Best regards,
> Krzysztof
> 
> -----------------------------------------------------------------------
> Dr. Krzysztof T. Chyzy                       e-mail: chris at oa.uj.edu.pl
> Astronomical Observatory                          uochyzy at cyf-kr.edu.pl 
> Jagiellonian University
> ul. Orla 171, 30-244 Krakow, Poland
> tel (+48 12) 4121771
> fax (+48 12) 4251318
> 
> 



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