[daip] Re: FITTP Error

[Eric Greisen]

Siow-Wang Lee writes:
 > Hello, 
 > 
 > I have attempted twice to write a large (about 2GB) UV line data 
 > set onto disk using FITTP. Both times I've got the following error
 > message: 
 > 
 > fft.as> FITTP1: Task FITTP  (release of 15OCT97) begins
 > fft.as> FITTP1: Writing to disk file: DATAFITZ:19980413.LINE.FITS
 > fft.as> FITTP1: ZTPOPD: using translated file name =
 > fft.as> FITTP1: ZTPOPD: /data2/swlee/arp244/FITS/19980413.LINE.FITS
 > fft.as> FITTP1: Writing UV data: User  117 Disk 3  Name 19980413.LINE.1
 > fft.as> FITTP1: Writing HI file
 > fft.as> FITTP1: Now writing the uv data
 > fft.as> FITTP1: ZTPWAT: ERROR   3 FOR LUN = 25 IBUFF = 1 TO DISK
 > fft.as> FITTP1: ZERROR: IN ZTPWAD ERRNO = 22 (Invalid argument)
 > fft.as> FITTP1: This usually means PARITY ERROR
 > fft.as> FITTP1: TAPIO: ERROR   3  WRITING FILE
 > fft.as> FITTP1: ERROR WRITING UV BINARY DATA TO TAPE:      3
 > fft.as> FITTP1: Appears to have ended successfully
 > fft.as> FITTP1: UN-REG 15OCT97 TST: Cpu=  339.21  Real=********  IO=
 > 0
 > 
 > After which the FITS file appears to be written. I then ftp the 
 > file to another computer, but couldn't UVLOD it. 

        The file was not written correctly as the error messages
state.  It does not suprise me that it could not be read correctly
elsewhere.  When FITTP writes UV data it must convert it from
compressed format to "normal" format - an increase in file size of as
much as a factor of 3.  If the file becomes > 2 Gbyte, I believe that
the routines used to write it will fail.  This is particularly true of
the antique version of AIPS that you are using.  You should have your
site update to a current AIPS - see my www page andd things to which
it points for the innumerable reasons why this is a good idea.
        http://www.cv.nrao.edu/~egreisen

Among other reasons - there is a new task FITAB that can write FITS
disk files in compressed form and the reading tasks in the new release
can read FITAB's files.

Eric Greisen