AIPS HELP file for SPLAT in 31DEC22
As of Sun Mar 26 9:33:08 2023
SPLAT: Split/assemble the sources in single/multi source file
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 #
SOURCES Source list
QUAL -1.0 Source qualifier -1=>all
CALCODE Calibrator code ' '=>all
TIMERANG Time range to copy
STOKES Stokes type to pass.
ANTENNAS Antennas to include or omit
SELBAND Bandwidth to select (kHz)
SELFREQ Frequency to select (MHz)
FREQID Freq. ID to select.
BIF 0.0 100.0 Lowest IF number 0=>all
EIF 0.0 100.0 Highest IF number 0=>all
BCHAN 0.0 2048.0 Lowest channel number 0=>all
ECHAN 0.0 2048.0 Highest channel number
SUBARRAY 0.0 1000.0 Subarray, 0=>all
DOCALIB -1.0 101.0 > 0 calibrate data & weights
> 99 do NOT calibrate weights
GAINUSE CL (or SN) table to apply
DOPOL -1.0 10.0 If >0 correct polarization.
PDVER PD table to apply (DOPOL>0)
BLVER BL table to apply.
FLAGVER Flag table version.
0 => highest numbered table
<0 => no flagging
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.
OUTNAME Output UV file name (name)
used in split option too
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 #.
DOUVCOMP -1.0 1.0 1 (T) => compressed data
APARM Control information:
1 = 1 => avg. freq. in IF
CHANNEL is not used
= 2 => avg IF's also
CHANNEL is not used
= 3 => average each
step by CHINC
ICHANSEL is not used.
2 = Input avg. time (sec)
3 > 0 => Drop subarrays
5 = 0 pass only xc data
= 1 pass xc and ac data
= 2 pass only ac data
6 > 0 add full source name
7 = 0 assemble all selected
sources in one
multiple source file.
> 0 split for single
ICHANSEL Array of channel start, stop,
and increment numbers and IF
number to be used when
averaging in frequency.
It's used if APARM(1)=1 or 2
CHANNEL Number of chans to average
together when APARM(1) = 3
CHINC Increment in input chans for
output when APARM(1) = 3
0 -> CHANNEL
SOLINT Time of averaging in min.
0 => no averaging
BADDISK 0.0 9999.0 Disks to avoid for scratch
Task: Split a multi source uv data set into single source data or
assemble the selected sources into new multi source file having
applied calibration and averaging data in time and in
frequency. Multiple sources may be processed in a single run.
Calibration and editing may be optionally applied. Fully
flagged data will not be copied.
SPLAT will also apply an unapplied SN table to a single-source
file. This may be done by copying an appropriate SN table to
the input file. A warning message may appear if the SN table
had previously been applied to any dataset.
SPLAT differs from SPLIT in that it can write a multi-source
output file and that it will copy calibration tables unless
they were applied. If a BP table is applied, no BP table is
copied. If DOCAL is true, no CL, SN, TY, or GC table is
copied. If an FG table is applied, no FG table is copied.
SPLIT copies no calibration tables under all circumstances.
Moving sources retain their PO information (if any).
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.
SOURCES....Source list. '*' = all; a "-" before a source name
means all except ANY source named. In the split option
separate single source file is created for each selected
QUAL.......Only sources with a source qualifier number in the SU table
matching QUAL will be used if QUAL is >= 0. If QUAL < 0,
all qualifiers will be written. These qualifiers will be
written to separate output files. Note that OUTSEQ must be
zero in this case.
CALCODE....Sources may be selected on the basis of the
calibrator code given in the SU table.
' ' => any calibrator code selected
'* ' => any non blank code (cal. only)
'-CAL' => blank codes only (no calibrators)
anything else = calibrator code to select.
NB: The CALCODE test is applied in addition to the
other tests, i.e. SOURCS and QUAL, in the
selection of sources to process.
TIMERANG...Time range of the data to be copied. In order:
Start day, hour, min. sec,
end day, hour, min. sec. Days relative to ref.
STOKES.....The desired Stokes type of the output data:
'LR','HALF' (=RR,LL), 'FULL' (=RR,LL,RL,LR),
' ' lives polarization without modification
ANTENNAS...A list of the antennas to include in the output data set.
If any number is negative then all antennas listed are
NOT to be included.
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 copy. 0=>all.
EIF........Highest IF to copy. 0=>all higher than BIF
BCHAN......First channel to copy. 0=>all.
ECHAN......Highest channel to copy. 0=>all higher than BIF
SUBARRAY...Subarray number to copy. 0=>all.
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 table to apply to
multi source files or the SN table for single
source files. 0 => highest.
DOPOL......If > 0 then correct data for instrumental polarization as
represented in the AN or PD table. This correction is
only useful if PCAL has been run or feed polarization
parameters have been otherwise obtained. See HELP DOPOL
for available correction modes: 1 is normal, 2 and 3 are
for VLBI. 1-3 use a PD table if available; 6, 7, 8 are
the same but use the AN (continuum solution) even if a PD
table is present.
PDVER......PD table to apply if PCAL was run with SPECTRAL true and
0 < DOPOL < 6. <= 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.
The flag table is also applied to any TY, SN, or SY
tables copied to the output file.
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
(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
BPVER......Specifies the version of the BP table to be applied if
DOBAND > 0. 0 => highest numbered table.
<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
OUTNAME....Output UV file name (name). Used, if the selected sources
assembled in one multiple source file with default INNAME.
In the split option, a non-blank OUTNAME is actually used
for all sources, with OUTSEQ forced to 0 after the first
output file. The default (OUTNAME=' ') is the first 12
characters of the name of the source. If more than one
"source" has the same name, the affected output file
names have the CALCODE and QUAL inserted in characters
OUTCLASS...Output UV file name (class). Standard defaults.
OUTSEQ.....Output UV file name (seq. #). 0 => highest unique
If QUAL = -1, OUTSEQ must be zero if there are in fact more
than one qualifier for a given source name.
OUTDISK....Disk drive # of output UV file. 0 => highest with
space for the file.
DOUVCOMP...If true (DOUVCOMP >= 0) the output data is written
in compressed format which can result in a
substantial reduction in disk space needed but only
calibration routines are likely to interprete this
data. If input data are in compressed format, the output
will be in compressed format also independent on DOUVCOMP.
If APARM(1) is equal to 1 then frequency channels
selected by ICHANSEL in each IF will be averaged to
produce one spectral channel per IF in the output.
CHANNEL, CHINC are not used
If APARM(1) is equal to 2, then the frequency channels
selected by ICHANSEL will be averaged in each IF and then
all IF's will be averaged. This produces a one
spectral-channel, one IF output or complete spectral
averaging of (calibrated) data.
WARNING: the output frequency will be corrected to the
averaged frequency as will the values of u,v,w, but any
IF-dependent editing will make this correction less than
accurate. Also the output data are computed by a
weighted average while the frequency is a straight
average. If weights vary significantly between IFs (and
they often do) then the corrections to u,v,w will not
have been correct and the error will be sample dependent.
If APARM(1) is equal to 3 then average each subsequent
CHANNEL input frequency channels. Increment by CHINC
channels in selecting output channels. (CHINC=0 ->
CHINC=CHANNEL). This can be used to diminish output data
set size. Note CHANNEL=1, CHINC=2 will output every other
channel (after application of calibration, SMOOTH etc).
Also note that one may do things like CHANNEL=4, CHINC=3
to produce output channels that are less independent than
those in the input. ICHANSEL is not used.
If phase rate corrections are to be done as part
of the calibration, then the integration time of
the input data must be given in APARM(2) to allow
for an amplitude correction to correct for the
effect of time smearing on the data. Default is no
If APARM(3) > 0 then drop the subarray code from
the visibility records.
If APARM(5) = 0 then SPLAT will pass only cross
power data, this is the default mode. If APARM(5)=1
then both cross-power and total-power data will be
passed; if APARM(5)=2 then only total-power data
will be passed.
If APARM(6) > 0, the full 16 character source
name is added to the header. The first 8 characters
in keyword SOURNAM1, the second 8 in keyword SOURNAM2.
If APARM(7) = 0, assemble all selected sources into
one multi source file having applied optionnaly
calibration and averaging in time and in frequency.
If APARM(7) > 0, the selected sources are splitted
into separate single source files.
ICHANSEL...The channels to be averaged when APARM(1) = 1 or 2 in the
form of an array of start and stop channels plus a
channel increment and the IF to which they apply. All 0
=> BCHAN, ECHAN, 1, 0. ICHANSEL(4,i) gives the IF and 0
means all IFs. Up to 20 groups of these 4 numbers may be
specified. Note that the channel numbers are absolute
numbers; they are NOT relative to BIF and BCHAN.
For instance if your data had a spectral line covering
channels 56 - 80, and you wished to exclude channels 1 -
10 and 121 - 128 because of bandpass effects, then you
could set APARM(1) = 2, and ICHANSEL = 11, 55, 1, 0, 81,
121, 1, 0 for a 1-IF data set. If you only wished to use
every other channel from the second group then you would
set ICHANSEL = 11, 55, 0, 0, 81, 121, 2, 0.
CHANNEL....Number of subsequent channels to average together.
Used when APARM(1) = 3
CHINC......Increment in input channels between output channels. Used
only when APARM(1) = 3. 0 -> CHANNEL. See discussion
above (for that APARM value) to see how it is used.
THIS IS SIGNIFICANT: If you start with 64 channels and set
CHANNEL=16 and CHINC=1, then you get 49 output channels
each of which contain 15 channels in common with the
previous output channel.
SOLINT.....Time of averaging in min. 0 => no averaging
Note that SPLAT uses the default time averaging method in
UVAVG. Options to write all baselines with the same
average time and to use a strict grid of times are
offered by UVAVG but not SPLAT.
BADDISK....A list of disks on which scratch files are not to
be placed. This will not affect the output file.
The assembling option is useful when delay and fringe rate have
become small enough as a result of the first stage of calibration.
This fact allows averaging in frequency and time to reduce the volume
of the data output.
For this data compression operation on VLBI data, the assembling
option should be applied after the first stage of calibration has been
carried out: ANTAB, FRING, ACCOR, PCCOR. SPLAT does not copy CL, GC,
PC, SN, TY tables if calibration is applied (DOCALIB > 0). The
calibration on the basis of these tables has to be carried out before
SPLAT (assembling option). In particular it is not a good idea to run
SPLAT (assembling option) with DOCALIB>0 if PCCOR has not run to
create calibration on the basis of pulse-cal tones.