[daip] UVGLU problem

[Linda Watson]

Dear AIPS Help Desk,

I am using the 31DEC08 version of AIPS to process 21cm emission line data 
from VLA.  We are using bandstitching to cover our spectral region of 
interest using the two IFs.  We would like to combine the IFs with UVGLU 
before continuum subtraction and imaging.

When I run UVGLU, AIPS completes the task without error.  But when I tried 
to use UVLIN to subtract the continuum from the glued file, AIPS gave the 
following error:

hypati> UVLIN1: Working on visibility record   150000
hypati> UVLIN1: ZMI2: REQUEST FOR BYTES 349282305 THRU = 349480796 BEYOND 
EOF =
hypati>         349408256
hypati> UVLIN1: ZMIO: OPER=READ LUN=25 BLKNO=      341097 
8-BIT-BYTES=198492
hypati> UVLIN1: ZERROR: IN ZMI2 ERRNO = 22 (Invalid argument)
hypati> UVLIN1: ZWAIT: ZWAI2 RETURNS ERROR 3 FOR LUN = 25 BUFFER = 2
hypati> UVLIN1: ZERROR: IN ZWAI2  ERRNO = 22 (Invalid argument)
hypati> UVLIN1: DATGET: ERROR  3 READING UV DATA
hypati> UVLIN1: UVLIUV: ERROR  3 READING VIS FILE
hypati> UVLIN1: Destroyed  1 extension files of type NX
hypati> UVLIN1: Destroyed UV image file: catno=     21 disk= 1
hypati> UVLIN1: Purports to die of UNNATURAL causes

I also tried to make an image of the glued file and tried to look at 
it in POSSM and both of those also gave the same error.  So it seems that 
I did something wrong in UVGLU.  The glued file perhaps is not as large as 
AIPS expects it to be?

Do you happen to have any suggestions for what I might have done wrong? 
I'm new to AIPS so this very well could be something simple.

Here are some basic tests that I did that might help you exclude 
possibilities:

1) I confirmed that I input the individual IF files in the correct order 
so that the first file is the lower frequency IF.

2) I have confirmed that I correctly trimmed overlapping channels between 
the IFs so that the first channel in the higher frequency IF is 0.024 MHz 
larger than the last channel in the lower frequency IF, where 0.024 is 
the number of MHz/channel.

3) I was able to image the individual IF files that I attempted to glue 
together so they do not seem to be corrupted.

I hope I have given you enough information to understand my problem. 
Hopefully it's not too silly!

Many thanks,
Linda

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Linda Watson
Graduate Student
Department of Astronomy
Ohio State University
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