AIPS HELP file for ICHANSEL in 31DEC18
As of Tue Jan 16 10:20:08 2018
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 use the center 75 percent of the channels for any
IF for which no ICHANSEL was specified.