AIPS NRAO AIPS HELP file for ICHANSEL in 31DEC18



As of Mon Jun 18 1:21:38 2018



HELP SECTION

ICHANSEL
Type: Adverb  (REAL, 4 elements x 20 rows)
Use:  Data selection adverb used to specify a list of start and stop
      channel numbers plus an increment AND IF NUMBER to be used in
      some way, such as to be averaged to form a pseudo-continuum
      channel.  Up to 20 sets of channel numbers/IFs can be specified.
      The first two elements specify the start and stop channel
      numbers, the third specifies the increment within that range,
      i.e.if CHANSEL = 10,20,2 that means take every other channel in
      the range 10 - 20, so that channels 10,12,14,16,18,20 would be
      averaged together.  The fourth element specifies the IF to which
      the previous three apply.
Null Value:  0
      A completely null value means use all channels in some tasks:
         ICHANSEL(1,i) <= 0  =>  1
         ICHANSEL(2,1) <= 0  =>  Nchan
         ICHANSEL(2,i) <= 0  =>  (i > 1) -> no more channel sets
         ICHANSEL(3,i) <= 0  =>  1
         ICHANSEL(4,i) <= 0  =>  all IFs
      BPASS, CPASS, AVSPC, REWAY and many other tasks use the center
      75 percent of the channels for any IF for which no ICHANSEL was
      specified.  Other tasks have different defaults including being
      unwilling to set defaults.
      Examples:
         ICHANSEL = 9,56         includes all channels 9-56 in all IFs
         ICHANSEL = 12,53,1,1, 62,116,1,1, 12,116,1,2
                                 includes all channels from 12-53 and
                                 62-116 in IF 1, and all channels from
                                 12-116 in IF 2.  If there are more
                                 IFs, default actions are taken.
         ICHANSEL = 17,112,1,0, 23,45,1,1, 87,112,1,1
                                 includes all channels from 17-112 in
                                 all IFs except IF 1 which includes
                                 channels 23-45 and 87-112.  NOTE
                                 WELL: the all IF instruction must
                                 precede any instruction that
                                 partially overrides it.

EXPLAIN SECTION


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