AIPS HELP file for TYAPL in 31DEC21
As of Fri Sep 17 14:25:09 2021
TYAPL: Undoes and re-does nominal sensitivity application
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 #
FREQID 0.0 Frequency ID number: 0 -> 1
SUBARRAY 0.0 Subarray: 0 -> 1
FLAGVER -1.0 > 0 => apply flags to output
data and TY/SY/SN tables
DOFLAG = 1,3 -> do NOT flag TY/SY
= 2,3 -> do NOT flag SN
INEXT TY or SY for VLA or EVLA
INVERS Input ?Y table undo 0=>none
IN2VERS Input ?Y table redo 0=>none
OUTNAME Output UV file name (name)
OUTCLASS Output UV file name (class)
OUTSEQ Output UV file name (seq #)
OUTDISK Output UV file disk unit
OPTYPE 'PGN' use SY post gain only
'CL' write CL table =bad idea
'CLP' write CL post gain only
REWEIGHT Additional SY scaling factors
for visibilities, weights
DOWEIGHT -1.0 1.0 < 0 => do NOT compute weights
from SY values
NOTE: 0 means do weights
CUTOFF 0.0 1.0 > 0 => if fraction of good SY
values < CUTOFF, apply an
average correction instead
FQCENTER >= 0 -> center frequency axis
CALIN Antenna efficiencies file
RPARM list of antenna to be set to
the average of good antennas
BADDISK Disks to avoid for scratch
Task: For the EVLA, the SysPower table in the SDM records the switched
power when the noise tube is on and the switched power when the
noise tube is off. If the AIPS files are obtained via OBIT ---
AIPS "verb" BDF2AIPS --- then an SY table is available. It may
be applied to adjust the gains and the data weights. If one has
been applied, the application may be removed and a new SY table
(i.e. one clipped and smoothed by TYSMO) may be applied. This
is much like the Tsys application done formerly for the VLA but
there are differences. For details, see EVLA Memo 145 by Rick
Perley (May 2010). TYSMO, SNEDT, EDITA, and SNPLT all
understand SY tables and allow you to manipulate and/or view
them. The task uses the input INTTIM random parameter where
available as the integration time and, if unavailable, assumes
that the input weights are equal the integration time. If you
have done frequency averaging, this will not be true and the
weights will be incorrect after TYAPL (if INTTIM is missing).
Do not use TYAPL if your data includes observations of the Sun.
Use appropriate tasks instead: SOLCL for VLA data and SYSOL for
Note that TYAPL with SY tables requires valid values for Pdif,
Psum, and the post-detector gains. If you have flagged data in
the SY table, TYAPL will flag the corresponding visibilities.
TYSMO allows you to replace flagged samples in the SY table with
averages from nearby samples. You should consider doing this
with all 3 data types before running TYAPL unlesss you want the
data to be flagged. The CUTOFF adverb allows you to specify a
minimum fraction of the SY table values that must be good (per
antenna, IF, polarization) in order to apply the table values.
If there is a lower fraction, then the average over the good
antennas for the particular IF and polarization will be applied
to the "bad" antennas.
TYAPL now has the ability to apply a flag table to the data as
they are read. Like UVCOP, up to 600001 flags are allowed to
apply to a single time. This ability was added so that you can
use the required data copy in TYAPL instead of an additional
data copy in UVCOP to reduce the size of the data and dispense
with large flag tables generated by auto-flag tasks like RFLAG.
Note that TYAPL should copy the data set for 3 reasons: 1. The
system gains may do abrupt jumps usually at the original scan
boundaries but sometimes at other times. A CL table could
handle these jumps if it was structured to match the original
scans, but that original structure is often lost. 2. The data
weights after TYAPL need to have the amplitude gains applied to
them as well as the visibilities since any amplitude gains at
that point should only reflect errors in the assumed Tcal's.
However, it is completely incorrect to apply the amplitude gain
from the SY table to the weights computed from the SY table.
The CL tables contain a cumulative amplitude gain and there is
no reasonable way to differentiate the SY table gains from the
other gains later in the processing. 3. New weights are needed
and TYAPL computes remarkably good ones. This means the data
set must be rewritten to supply those weights and it is
completely unsafe to overwrite the input data set.
For the VLA, Tsys is the nominal sensitivity and Tant is some
form of system temperature. FILLM, by default, scales the
measured correlation coefficients by the instantaneous measured
nominal sensitivities, producing data approximately in deci-Jy.
FILLM can be told to load correlation coefficients only. For
calibration purposes, it is best to have the nominal
sensitivites applied, but it may be better to use a clipped and
time-smoothed version of those sensitivities. TYSMO allows you
to do that clipping and smoothing or, if you prefer interactive
tasks, try SNEDT. Then one can remove the nominal sensitivities
applied by FILLM, if any, and apply smoothed nominal
sensitivites (or leave the data as correlation coefficients if
desired) with TYAPL.
VLBI users warning: This task is not elaborately intelligent
about looking through the TY table to match up Tsys measurements
by source and time. It is tested for and assumes the simple,
all antennas at the same time and source form for the TY tables
of the VLA.
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.
FREQID.....Frequency ID number to do 0 => 1
SUBARRY....Subarray to do 0 => 1
FLAGVER....If > 0, apply the specified flag table version to the
data and do not copy it to the output. Unlike regular
calibration routines (but like UVCOP), FLAGVER = 0 means
no flagging. The flag table is applied to any TY, SY,
and SN tables as they are copied (spectral-channel
independent flags only).
DOFLAG.....Controls whether FLAGVER is applied to tables or not.
= 0 => apply FLAGVER (if > 0). If 1 => do not flag SY
and TY tables, =2 => do not flag SN tables, =3 => do NOT
flag SN, SY, or TY tables.
INEXT......Input extension type: 'SY' for SysPower tables from the
VLA, 'TY' for System Temperature tables from the (old)
VLA. ' ' takes whichever one it finds.
INVERS.....Input version number of the TY table which was applied to
the data and is to be unapplied. 0 => none
If input file is in correlation coefficient form, it is
an error to set INVERS > 0.
IN2VERS....Input version number of the ?Y table that is to be
applied after INVERS is undone. 0 => none
If the data are not in correlation coefficient form on
input or after INVERS is undone, then it is an error to
set IN2VERS > 0.
If INVERS <= 0 and IN2VERS <= 0, then the program will
set IN2VERS to max ?Y version if the data are correlation
coefficients and INVERS to max ?Y version if the data are
in visibility form, leaving the other at 0.
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....Output UV file disk unit. 0 => highest w space.
OPTYPE.....'PGN' use the SY table post-gain only to adjust gains
The following are a bad idea for reasons given above:
'CL' apply the TY or SY gains to the highest CL table
version and write a new CL table
'CLP' write the SY table post gain into a new CL table
In the case of the above three OPTYPEs, DOWEIGHT is set
to -1. If you do the CL operation, you must compute
weights with REWAY and only with DOCAL true.
Any other value of OPTYPE does the normal operations with
Pdif and Psum from the SY table and will write a new data
set with weights controlled by the user-chose value of
REWEIGHT...Scale the visibilites by REWEIGHT(1) and the weights by
REWEIGHT(2). This option is allowed for now on SY tables
only since the correct scaling is uncertain. 0 -> 1
DOWEIGHT...>= 0 => compute weights from SY values, < 0 do not change
input weights. NOTE the non-standard use of the logical
in which 0 is true. If OPTYPE = 'PGN', 'CL', or 'CLP',
DOWEIGHT is set to false.
CUTOFF.....<= 0 => data for which there is not a valid SY table
value are flagged.
> 0 => The SY table is examined in advance. If the
fraction of valid SY table entries for a
particular polarization, IF, and antenna is less
than CUTOFF, the gain and weight factors for that
antenna, IF, and polarization will be taken to be
the average of those parameters for the antennas
that are not "skipped". The data are not flagged.
FQCENTER,..> 0 => Change frequency axis reference pixel to
Nchan / 2 + 1
else => do not change reference pixel
CALIN......The name of a text file to provide antenna efficiencies
as a function of antenna, frequency, and polarization.
By default, the system file is called:
If it is missing, a small table which is antenna and
polarization independent is used instead.
RPARM......List of antennas to be "skipped" - i.e. corrected with the
average of the corrections for good antennas. Correction
is a function of polarizations and IF. Use this isf the SY
values are not right but not obviously invalid. CUTOFF is
useful for obvious cases.
BADDISK....The disk numbers to avoid for scratch files (sorting