Message 8/504 Mike Garrett                           Oct 17, 2000 02:27:12 pm
+0200

Date: Tue, 17 Oct 2000 14:27:12 +0200 (MET DST)
X-Sender: mag@juw05
To: evntech@jb.man.ac.uk
Subject: EVNtech: Calibration transfer
Sender: owner-evntech@jb.man.ac.uk
Precedence: bulk


           Calibration Transfer Report - M.A. Garrett.

At the last directors meeting there was some pressure on the TOG to
investigate whether the EVN could adopt "Calibration Transfer" procedures
similar to that used by the VLBA. Calibration transfer means that for
example, the TSYS data (and associated gain tables) are made available to
the user as a table that is already attached to the correlated FITS file
(rather than the situation at present in the EVN - an ANTAB file
available by ftp from VLBEER must be applied to the data using several
AIPS tasks). The advantages of the calibration transfer system are that
the amplitude calibration process is transparent to the user. The VLBA
correlator implements calibration transfer automatically (for VLBA
telescopes) but might need extra software development for the EVN ANTAB
files. Calibration transfer is also planned by the EVN Data Processor at
JIVE.

My feeling is that we can only adopt this procedure when:

(1) progress has been made in the FS w.r.t. (a) robust TSYS measurements,    
    and (b) the post processing of ANTAB files is near
    automatic

(2) the stations are prepared to ensure (as best they can) that the data
    can be used "blindly" i.e. they are accurate calibrated.


There may be more caveats but can't think of any more at the moment!

M.

------------------------------------------------------------------------
            Mike Garrett         (garrett@jive.nl & www.jive.nl/~mag)
          EVN Support Group
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  - Menzies Campbell's tribute to the First Minister for  Scotland,
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