[daip] [Fwd: [Vlahelp] task vlant]

[Eric Greisen]

Gustaaf Van Moorsel wrote:
> This seems more of an AIPS question, so I am sending
> it to daip.  Thanks!
> 
> Gustaaf
> 
> -------- Original Message --------
> Subject: [Vlahelp] task vlant
> Date: Thu, 10 Dec 2009 12:26:25 +0100
> From: Luciano Cerrigone <lcerrigone at mpifr.de>
> To: vlahelp at nrao.edu
> 
> Hello,
> I am reducing a VLA dataset from 2006. The antennas had been recently
> moved before the observations were carried out, so I need to correct
> their positions. In the past I usually used CLCOR, but VLANT is
> obviously much faster and easier. Yet, there is something not clear to
> me about this task. It seems to me that the task applies the latest
> baseline corrections to the dataset, no matter when the observations
> were performed. In my case, it seems to be applying position corrections
> obtained in 2009 to my 2006 dataset (it fetches the file
> baselines.vlais09 from the VLA web site).
> Am I doing anything wrong?

No.  The task carefully watches the files and as soon as a particular 
antenna moves from the station used for your data, then the corrections 
made for that antenna and/or station later are ignored.  But 3 antennas 
never move (except for the EVLA upgrade) and so it keeps reading until 
all antennas have been flagged as done or the data runs out whichever 
comes first.  It will list any antennas that might still get more 
corrections were you to run VLANT 6 months from now.  Except of course 
that all this runs out when we shut down the VLA and start running the 
EVLA early next year.

Eric Greisen