AIPS HELP file for BASRM in 31DEC22
As of Fri May 20 13:28:33 2022
BASRM: Task to remove a spectral baseline from total power
INNAME Input UV file name (name)
INCLASS Input UV file name (class)
INSEQ 0.0 9999.0 Input UV file name (seq. #)
INDISK 0.0 9.0 Input UV file disk unit #
OUTNAME Output UV file name (name)
OUTCLASS Output UV file name (class)
OUTSEQ -1.0 9999.0 Output UV file name (seq. #)
OUTDISK 0.0 9.0 Output UV file disk unit #.
SELBAND Bandwidth to select (kHz)
SELFREQ Frequency to select (MHz)
FREQID Freq. ID to select. 0=> all
APARM (1) Order of polynomial
(2) > 0 => Write out
polynomials, not spectra
(3) > 0 => print polynomial
coefficients on screen.
ICHANSEL Array of start and stop chn
numbers, plus a channel
increment and IF to be used
for channel selection in the
fitting. See HELP ICHANSEL.
Default = center 75 percent of band.
Task: This task will copy a uv data set removing a spectral
baseline from total power data along the way. Cross-power data
are untouched by this operation. The user is able to fit and
remove an nth order polynomial from line-free channels of the
total power spectra. The fit is done one IF and one polarization
at a time.
NOTE: this task does NOT apply flagging or calibration tables
to the input UV data. Run SPLIT first if that operation is
INNAME.....Input UV file name (name). Standard defaults.
INCLASS....Input UV file name (class). Standard defaults.
INSEQ......Input UV file name (seq. #). 0 => highest.
INDISK.....Disk drive # of input UV file. 0 => any.
OUTNAME....Output UV file name (name). Standard defaults.
OUTCLASS...Output UV file name (class). Standard defaults.
OUTSEQ.....Output UV file name (seq. #). 0 => highest unique
OUTDISK....Disk drive # of output UV file. 0 => highest w room
SELBAND....Bandwidth of data to be selected. If more than
one IF is present SELBAND is the width of the
first IF required. Units = kHz.
SELFREQ....Frequency of data to be selected. Units = MHz.
FREQID.....Frequency identifier to select (you may determine
which is applicable from the OPTYPE='SCAN' listing
produced by LISTR). If either SELBAND or SELFREQ
are set, their values overide that of FREQID.
However, setting SELBAND and SELFREQ may result in
an ambiguity. In that case, the task will request
that you use FREQID. (.le. 0 => all). If you select
data with the FREQ adverbs BASRM will renumber the
FREQID in the output file to 1, i.e. you can set
FREQID to the default value for all subsequent
operations on the output file.
APARM......(1) Order of the polynomial to be removed, 0=>
constant offset only.
(2) if > 0 replace the total power spectra in the
output file with the polynomial fitted to the
line-free channels rather than just writing
out the corrected spectra.
(3) if > 0 will print fitted polynomial coefficients for
each spectrum (IF, polarization, antenna)
ICHANSEL...Array of start and stop channels plus a channel increment
and IF, used to select the channels to be fit. NOTE:
BASRM forces the channel increment to 1. For instance, if
you wished to exclude channels 1 - 10 and 121 - 128 because
of bandpass effects, and channels 56 - 80 of IF 1 but not IF
2 because of interference, then you would set ICHANSEL =
11,55,1,1, 81,121,1,1, 11,121,1,2. Up to 20 groups of
start, stop and increment channel numbers plus IF numbers
can be specified. The default (ICHANSEL = 0) is to use the
center 75 percent of the band, i.e.
ICHANSEL(1,1) = (# channels)/8 + 1
For example: # channels=16 => ICHANSEL(1,1)=3
ICHANSEL(2,1) = (# channels + 1)*7/8
For example: # channels=16 => ICHANSEL(2,1)=14
ICHANSEL(3,1) = 1
ICHANSEL(4,1) = 0 (meaning all IFs).
If ICHANSEL describes fitting explicitly for some IFs,
but skips other IFs, then the center 75 percent of the band is
fit for the skipped IFs. For example:ICHANSEL=2,6,1,2 =>
channels 2-6 will be fit for IF=2 and the center 75 percent of the
band will be fit for the rest of the IFs.