[daip] The header before and after AVSPC

[Eric Greisen]

$AKo4+:C(B writes:
 > 
 > The header before AVSPC was run:
 > >imh
 > AIPS 1: # visibilities     53759     Sort order  TB

 > AIPS 1: FREQ         1   4.9729900E+09       0.50  2.0000000E+06    0.00
 > AIPS 1: IF          14   1.0000000E+00       1.00  1.0000000E+00    0.00

 > AIPS 1: ICHANSEL   *all 0                  Array of start and stop chn
 > AIPS 1:                                    numbers, plus a channel
 > AIPS 1:                                    increment and IF to be used
 > AIPS 1:                                    for channel selection in the
 > AIPS 1:                                    averaging. See HELP ICHANSEL.
 > AIPS 1:                                    Default = center 75% of band.
 > AIPS 1: AVOPTION   'SUBS'                  Averaging option '  ','SUBS'
 > AIPS 1: FLAGVER       0                    Flag table version
 > AIPS 1: CHANNEL      14                    # chans to average together
 > AIPS 1:                                    used when AVOPTION = 'SUBS'

 > The header after AVSPC was run:

 > AIPS 1: # visibilities     53759     Sort order  TB

 > AIPS 1: FREQ         0   4.9729900E+09       0.50  2.8000000E+07    0.00
 > AIPS 1: IF          14   1.0000000E+00       1.00  1.0000000E+00    0.00

The reason for things not working is the 0 above for number of
frequencies.  AVSPC does not average IFs together so what you
attempted to do is not offerred by the task.  I am surprised by the
useless output it produced.  Tasks SPLIT and SPLAT do have the option
to average IFs.

Eric Greisen