AIPS HELP file for SPCAL in 31DEC24
As of Thu Apr 25 8:43:43 2024
SPCAL: Task to compute instrumental polzn. for spec. line data
INPUTS
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 #
Data selection (multisource):
CALSOUR Sources to calibrate with
TIMERANG Time range to use.
SELBAND Bandwidth to select (kHz)
SELFREQ Frequency to select (MHz)
FREQID Freq. ID to select.
BIF 0.0 100.0 IF number.
ANTENNAS Antennas to solve for.
UVRANGE 0.0 UV range in kilolamdba
SUBARRAY 0.0 1000.0 Subarray, 0=>all
BCHAN 0.0 2048.0 Lowest channel number 0=>all
ECHAN 0.0 2048.0 Highest channel number 0=>all
Cal. info for input:
DOCALIB -1.0 101.0 > 0 calibrate data & weights
> 99 do NOT calibrate weights
GAINUSE CAL table to apply.
BLVER BL table to apply.
FLAGVER Flag table version
DOBAND -1.0 10.0 If >0 apply bandpass cal.
Method used depends on value
of DOBAND (see HELP file).
BPVER Bandpass table version
SMOOTH Smoothing function. See
HELP SMOOTH for details.
SOLINT Soln. interval (min) 0=>10.
SOLTYPE Soln. type:
'ZAPR': zero. lin. pol.
'RAPR': similarity method
PRTLEV 0.0 10.0 Print statistics 0=>none
1 = some, 2 = lots. Use 1.
REFANT 0.0 90.0 Reference antenna, 0=none.
BADDISK 0.0 9.0 Disk no. not to use for
scratch files.
HELP SECTION
SPCAL
Task: This task reads a spectral line uv-data file, applies
calibration and determines the feed polarization parameters
for each antenna for the selected IF. The instrumental
polarization parameters are recorded in the AN table and can
be applied in LISTR, SPLIT or other tasks by setting DOPOL>0.
Adverbs:
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.
The following are used for multisource data files only:
CALSOUR....List of sources for which calibration constants
are to be determined. '*' = all; a "-" before a
source name means all except ANY source named.
Note: solutions for multiple sources can only be
made if the sources are point sources at their
assumed phase center and with the flux densities
given in the source (SU) table. All ' ' =>all.
TIMERANG...Time range of the data to be used. In order:
Start day, hour, min. sec,
end day, hour, min. sec. Days relative to ref.
date.
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. For data which
contain multiple bandwidths/frequencies the task
will insist that some form of selection be made
by frequency or bandwidth.
SELFREQ....Frequency of data to be selected. If more than
one IF is present SELFREQ is the frequency of the
first IF required. 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 override that of FREQID.
However, setting SELBAND and SELFREQ may result in
an ambiguity. In that case, the task will request
that you use FREQID.
BIF........First IF to process. Old values for feed parameters
and calibrator polarizations for unprocessed IFs
are unchanged. 0=>all.
ANTENNAS...A list of the antennas to have solutions
determined. If any number is negative then all
antennas listed are NOT to be used to determine
solutions and all others are. All 0 => use all.
The following may be used for all data files (except as noted):
UVRANGE....Range of projected spacings to be included in
1000's of wavelengths. 0 => 1, 1.E10
SUBARRAY...Subarray number to use. 0=>all.
BCHAN......Lowest channel number included; 0 -> 1
ECHAN......Highest channel number included; 0 -> max
DOCALIB....If true (>0), calibrate the data using information in the
specified Cal (CL) table for multi-source or SN table for
single-source data. Also calibrate the weights unless
DOCALIB > 99 (use this for old non-physical weights).
GAINUSE....version number of the CL or SN table to apply to
the data. 0 => highest.
BLVER......Version number of the baseline based calibration (BL)
table to appply. <0 => apply no BL table, 0 => highest.
FLAGVER....Specifies the version of the flagging table to be
applied. 0 => highest numbered table. <0 => no flagging
to be applied.
DOBAND.....If true (>0) then correct the data for the shape of the
antenna bandpasses using the BP table specified by BPVER.
The correction has five modes:
(a) if DOBAND=1 all entries for an antenna in the table
are averaged together before correcting the data.
(b) if DOBAND=2 the entry nearest in time (including
solution weights) is used to correct the data.
(c) if DOBAND=3 the table entries are interpolated in
time (using solution weights) and the data are then
corrected.
(d) if DOBAND=4 the entry nearest in time (ignoring
solution weights) is used to correct the data.
(e) if DOBAND=5 the table entries are interpolated in
time (ignoring solution weights) and the data are then
corrected.
BPVER......Specifies the version of the BP table to be applied.
<0 => no bandpass correction to be applied.
SMOOTH.....Specifies the type of spectral smoothing to be applied to
a uv database . The default is not to apply any smoothing.
The elements of SMOOTH are as follows:
SMOOTH(1) = type of smoothing to apply: 0 => no smoothing
To smooth before applying bandpass calibration
1 => Hanning, 2 => Gaussian, 3 => Boxcar, 4 => Sinc
To smooth after applying bandpass calibration
5 => Hanning, 6 => Gaussian, 7 => Boxcar, 8 => Sinc
SMOOTH(2) = the "diameter" of the function, i.e. width
between first nulls of Hanning triangle and sinc
function, FWHM of Gaussian, width of Boxcar. Defaults
(if < 0.1) are 4, 2, 2 and 3 channels for SMOOTH(1) =
1 - 4 and 5 - 8, resp.
SMOOTH(3) = the diameter over which the convolving
function has value - in channels. Defaults: 1,3,1,4
times SMOOTH(2) used when input SMOOTH(3) < net
SMOOTH(2).
SOLINT.....Time interval to average data before determining
correction in min. 0 => 10 min.
SOLTYPE....Solution type:
'ZAPR': assumes zero linear polarization.
'RAPR': assumes linear polarization is scaled
version of the total intensity.
else -> ZAPR
PRTLEV.....If this value is larger than 0.0 then the
intermediate diagnostics and solutions will be
given on the monitor terminal and the message file.
REFANT.....Reference antenna to use. If none is specified, the
program will pick the lowest numbered, most extensively
used one. The technique of using no reference antenna
has been found not to work well.
BADDISK....Disk numbers on which scratch files are not to
be placed.
EXPLAIN SECTION
SPCAL: Task to determine effective feed polarization
parameters for spectral line data.
Documentor: A. J. Kemball
Related Programs: CALIB, LISTR, SPLIT, CLCOR, LPCAL, PCAL
PCAL, SPCAL or LPCAL?
PCAL was designed for the VLA and works well for unresolved
or slightly resolved calibrators with uniform polarization.
LPCAL was designed for VLBI and allows the use of calibrators
that have significant structure and differential polarization
across the source. It will also handle unpolarized calibrators.
SPCAL was designed for spectral line experiments and solves
for frequency dependent D-terms. Like PCAL SPCAL demands
an unresolved calibrator.