[daip] Cookbook section 4.4.4 (Baseline corrections) [repeat]

[Michael Rupen]

This is a repeat of yesterday's e-mail, per Eric's request...


Dear DAIP,
     having been working on VLA baseline corrections recently, I was looking at
the on-line version of the AIPS Cookbook (31DEC04,
http://www.aoc.nrao.edu/aips/cook.html#C04) and had a couple suggestions.

* The text occasionally (but not consistently) implicitly assumes VLA data
     (for example 1st sentence "e.g., during an array re-configuration").   Not
     sure whether this is a bug or a feature.

* The 3rd para, beginning "If baseline errors are significant...", is out of
     date.
     - The details are definitely only for the VLA, and should be so indicated.

     - I have never seen a cover letter sent out to tell observers their data had
       significant baseline errors.    Maybe this happened for very egregious cases in the
       past, but these days we rely entirely on a message in the operator comments (aka
       observing log), of the form
         Antennas XXX have been moved recently...
       and/or
         The positions of antennas YYY have been updated recently...
       One might also mention that baseline errors are likely to be particularly large
       during and immediately after VLA reconfigurations.

       These logs are sent to the PI, and are also available on-line at
         http://www.vla.nrao.edu/astro/archive/obslogs/
       though only for 1989 on.  Of course it's likely that the 1980s logs followed a
       different convention for baseline complaints anyhow...

     - vlais doesn't seem to work anymore:
       > slogin zia
       > vlais
       The initialization file was not found.

       This is OK though, since the baseline data is now available on the VLA
       Web site:
         http://www.vla.nrao.edu/astro/archive/baselines/
       which is (confusingly) linked from the VLA Calibration section of the astronomer's
       VLA Web site
         http://www.vla.nrao.edu/astro/

That's it for now --

              Michael