[daip] forwarded message from Lincoln J. Greenhill

[Eric Greisen]

Leonia/Amy can you together look at this?

E
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From: "Lincoln J. Greenhill" <greenhill at cfa.harvard.edu>
To: aipsmail at cv3.cv.nrao.edu
Subject: FRING / Aparl(5)=0 vs 2 / difference in behavior 1998 vs today
Date: Thu, 19 Apr 2001 17:41:14 -0400

Dear AIPS group,

I am comparing results of FRING processing of VLBA data performed in
1998  (w/ 15OCT98) and today (w/ 31DEC00).

I find that in my past processing, I used aparm(5)=2 and obtained good
results (scan to scan changes
in delay of 1 ns)
.
Today, I find that use of aparm(5)=2 gives rotten solutions (50 and 100
ns jumps from hour to hour).
However, use of aparm(5)=0 gives good solutions again.

This data set has a nonuniform frequency grid.  8 IFs.  No.s 1 and 2
have the same frequency.
The others overlap at the 10% level and are spread over 100 MHz.

I have on consulted change.doc but come to no clear conclusion.  Are you
aware of changes to FRING
that would make it less robust today to such a non-standard dataset in
the context of multi-band delay solutions?
I would like to understand this better and as usual worry that something
unexpected may be occurring.

Regards,

Lincoln



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