[daip] aips related

[Eric Greisen]

Dharam Vir Lal writes:
 > 
 > Dear Eric,
 > 
 > I am running IMAGR task.  the UVDATA consists of 121 stations, simulated 
 > at 1.4 GHz and i am making a map using 120 baselines (station at origin, 
 > i.e., antenna 1 with rest 120 stations placed on a spiral arm).  the 
 > minimum baseline being 10m and maximum baseline being 3,000,000m.
 > 
 > Everything looks ok, but, please look at the output from the message 
 > window.  it seems stations from 91 to 121 are not included in the process 
 > of imaging?  am i correct and please explain the error message.  the 
 > antenna table has correct entries.
 > 

 > VLB003> IMAGR1: GETANT: STATION NUMBER    91 FOR ENTRY=  91 SUBA=  1
 > VLB003> IMAGR1: GETANT: STATION NUMBER    92 FOR ENTRY=  92 SUBA=  1

These are warning messages from the routine that fills an array of
antenna information.  IMAGR determines and average parallactic angle
etc at the end and then uses the antenna info to do it.  AIPS is by
defalut built with 90 as the maximum antenna number.  The include file
$INC/PUVD.INC controls this.  Since you are unlikely to want the
average elevation and parallactic angle for anything (useful really
only for snapshot images), these errors are of no consequence to the
image.  All baselines are included in the image without regard for the
antenna numbers - unless you specify ANTENNAS and BASELINE.  Then the
limit of 90 might be relevant.

You can check this by making a 90 stataion data set matching your
larger one and see if the images are different.

Eric Greisen