[daip] VLBA autocorrelations / ACCOR corrections

[Lincoln Greenhill]

Dear Leonia,

I have come across a case in which the results of ACCOR seem to depend on
source ID for VLBA data, which I understand runs counter to expectation.

Please see the attached PS file (name: TTT) that shows the results for
ACCOR (SN1). I direct you to the VLA solutions.  So that you can follow
the scans, I also attach a TASAV file that has NX/SU files (name:
TTT.FITS.gz).  

Leonia - What causes this correlation with source ID?

I am also curious about the frequency averaged amplitude of VLBA
autocorrelation spectra that I observe in many experiments. It is my
understanding that these spectra are normalized.  I routinely
notice variations in amplitude with time on the order of a few percent. I
am especially interested by (1) isolated discrepant points that are 5+%
away from neighboring points and (2) structure in these time variations
that includes slopes (a la wrapping between two boundary values)
and modulations in dispersion that look envelopes degined by sync
functions.

Jon - what causes this?


Regards,

Lincoln


Lincoln J. Greenhill      Harvard-Smithsonian Center for Astrophysics 
Radio & Geoastronomy Division, 60 Garden St, Cambridge, MA 02138, USA
Telephone:  1 617-495-7194             FAX:  1 617-495-7345
Internet:  greenhill at cfa.harvard.edu   http://cfa-www.harvard.edu/~lincoln
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