[daip] sensitivity

[Matthew Sharp]

hi Amy,

   Thanks for getting back to me.  I've scrapped my data to try
recalibrating.  I'll try again to find any messages indicating an
error when it tries to calibrate the data, but I thought it was
working fine.  Also, when I run SPLIT with identical arguments except
for setting source to only one target, it seems to calibrate without
problem, so I assume that a) the calibration exists and is findable by
the task, and b) SPLIT knows to use the calibration when only one
source is asked for...I'll get back to you if there are any messages
generated when I am able to repeat the experiment...

    Standing in my way is a separate calibration question.  My data
spans four separate days, and I used 3C147 to flux calibrate on each
day.  When I read the data in using FILLM, I immediately plot the
amplitude of my calibrator vs time, and see tremendous variation with
time.  Attached is an example of a single baseline, in which 3C147
varies from 3Jy to half a Jy over short timescales.  GetJY tells me
that the flux at 8GHz should be 4.7Jy.

     Previously, I've just ignored this variation and allowed it to
calibrate it away, but I can't believe that the VLA has this much
variation over a day...is it possible that I'm misusing FILLM in some
way that is screwing up my entire calibration?  Are you surprised by
amplitude fluctuations on the flux calibrator of nearly an order of
magnitude, or by the fact that the pre-calibration flux is a tenth of
the true value?  I'm not very clear on what has been done to the raw
data files from the VLA to put them into units of Jy, and whether i
should expect it to be in less dramatic disagreement with reality...

    Below I've included my command for reading and plotting the data.

thanks again

Matthew





default 'fillm'
task 'fillm'
INFILE     'MYAREA:as882/AS882_
NFILES        0
DOWEIGHT      1
DOUVCOMP     -1
band ''
calcode ''
timer 0
bchan 1
echan 0
CPARM(8)=1/60
QUAL         -1
INDISK        1
OUTNAME    ' '
OUTSEQ        0
OUTDISK       1
APARM         0
BPARM         0
DPARM         0
VERSION       ''
VLAOBS        ''
GO



TASK 'UVPLT'
default UVPLT
BPARM 5,1,0
source '0542+498'''
timer 0
dotv 1








On 5/29/07, Amy Mioduszewski <amiodusz at nrao.edu> wrote:
> Hi Matthew,
>
> Eric is out sick today.  You are right, when you SPLIT with blank SOURCES and
> there is calibration for all the sources in your highest CL table then the each
> source should be calibrated.  What are the messages?  Does it say it is applying
> the calibration?  Are any of the sources calibrated when you leave SOURCES
> blank?  I did some testing on data of mine and it seemed to do the right thing,
> but I didn't use the exact same inputs as you did.
>
> Cheers,
>
> Amy
>
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