[daip] Re: FRING (fwd)

[Ketan Desai]

I'm afraid I don't have the time to give a good detailed reply.
I seem to remember his original situation.  KRING was finding good
fringe-fit solutions only between antennas in two disjoint groups.
I don't think he has any good options but I will let you guys respond to
him.

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Date: Fri, 28 Apr 2000 16:48:26 +0900
To: "K. Desai" <kdesai at zia.aoc.NRAO.EDU>
From: zshen at hotaka.mtk.nao.ac.jp (Zhi-Qiang Shen)
Subject: Re: FRING
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Hi Ketan,

I come again after a quite long time. I expected to meet you in China
during the IAU Coll 182, but you didn't appear. So, I am writing ... .

I did what you suggested to register the fringes on a single baseline
which is isolated from the others. So, as you said, we have two
"subarray"in the sense of fringefitting. What I am not so clear is
what you said below about the inconsistency in applying the CL 
table. Would you please tell me more about this?

I did a test on some strong compact sources which have very good
fringes on all baselines. I deliberately single out 2 antennas to
do fringefitting also. Then I compared the delay solutions to these
two antennas. I found there is difference as large as 3 nanoseconds.
If I only run FFT (No LLS) in the global fringefitting (using all the 
antennas), the difference becomes small (about 1 nanosecond).

I also tried baseline-based fringefitting "BLING", but got no lucky.
It seems that "BLING" has changed a lot compared to my last try
in 1995-6. It didn't work properly. Do you know why?

I am working on the Sgr A* data, such kind of detection is really
important for us to constrain its VLBI structure.

Cheers,
Zhiqiang

>In some sense, you really don't want that data to make it through - at
>least not for astronomical work I think.  Anyway if you want it to come
>through, you can re-run FRING specifying those two antenna alone, and
>choosing not to re-reference phases - that should work. I must warn you that
>this will leave entries in the CL table that cannot all be applied 
consistently
>to the data.  You need have some connection between the two 'subarrays'.
>
>
>-ketan


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-- ketan
M.O.T.U.