[daip] 3C 48 model

[Amy Mioduszewski]

Hi Jim,

Well, there is a strongish confusing source to the north of the 3C48 so that 
might have something to do with it.  What frequency (exactly) did you observe 
at?  I think this is the first model I made, so I may have put it together wrong.

Amy

Jim Ulvestad wrote:
> Hi Amy et al.,
> 
> I'm reducing a data set from 2002, A configuration, X band,
> with 3C 48 as the only flux calibrator, using VLACALIB.
> VLACALIB is clearly picking up the model, as I get a new
> image/CC file for 3C 48 showing up in my directory every
> time I run it.
> 
> But I'm getting many amplitude closure errors in the 10-20%
> range, concentrated in the antennas on the North arm.
> The source was not observed exactly at transit, but about
> 2.25 hours from transit.  There is an adjacent calibrator
> at 0151+277 (4 deg. away in RA, 6 deg. in dec.), observed
> 5 minutes apart, that shows no errors at all, leading me
> to believe this shouldn't be atmosphere.  Over a 3.5
> minute scan, the phases do reasonably well, wrapping up
> to 30-40 deg. on some baselines, more typically 20 deg.
> or so.
> 
> I can't find any bad data in LISTR, though I will look
> a little bit more.
> 
> Yes, I did run SETJY first.
> 
> So my question is, have you typically seen this level of
> amplitude closure problems on 3C 48 even with your model?
> I recall that X-band A array used to be a kind of bad
> circumstance to use 3C 48 in; the calibrator manual says
> to use only the inner 2 antennas.  Is it possible that the
> source has enough structure that the model just doesn't do
> well enough?
> 
> Thanks,
> 
> Jim
> 
> 
> 
> _______________________________________________
> Daip mailing list
> Daip at listmgr.cv.nrao.edu
> http://listmgr.cv.nrao.edu/mailman/listinfo/daip
>