AIPS HELP file for RLDLY in 31DEC24
As of Fri Apr 26 6:58:56 2024
RLDLY: Task to fringe fit data for R-L delay difference
INPUTS
Input uv data.
INNAME UV file name (name)
INCLASS UV file name (class)
INSEQ 0.0 9999.0 UV file name (seq. #)
INDISK 0.0 9.0 UV file disk drive #
Data selection (multisource):
CALSOUR Calibrator sources
QUAL -10.0 Calibrator qualifier -1=>all
CALCODE Calibrator code ' '=>all
SELBAND Bandwidth to select (kHz)
SELFREQ Frequency to select (MHz)
FREQID Freq. ID to select.
TIMERANG Time range to use.
IMPORTANT, NO DEFAULT
BCHAN 0.0 2048.0 Lowest channel number 0=>all
ECHAN 0.0 2048.0 Highest channel number
CHINC 0.0 Spectral channel increment
(data are averaged)
ANTENNAS Antennas to select. 0=all
SUBARRAY 0.0 1000.0 Subarray, 0=>all
UVRANGE Range of uv distance for full
weight
WTUV Weight outside UVRANGE 0=0.
WEIGHTIT 0.0 3.0 Modify data weights function
Cal. info for input:
DOCALIB -1.0 101.0 > 0 calibrate data & weights
> 99 do NOT calibrate weights
GAINUSE CL 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
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.
Solution control adverbs:
REFANT 0.0 Reference antenna 0 -> all
DETIME Data integration time (sec)
0 => found in data
SOLINT -1.0 Separate solutions each
SOLINT (minutes)
DOIFS -1.0 64.0 <0 => use BPARM
0 => solve all IFs separately
1 => 1 solution for all IFs
2 => 2 solutions, 1 each for
IFs by halves
3 => 3 solutions, 1 each for
IFs by thirds
4 => 4 solutions, 1 each for
IFs by quarters
etc. SEE HELP WARNING
BIF First IF included when
DOIFS > 0
EIF Last IF included when DOIFS>0
BPARM 0.0 BPARM(i) = highest IF in i'th
group if DOIFS = -1
APARM (1) Minimum SNR to include in
solution average 0 -> 5
(2) > 0 -> do NOT write CL
table even when 1 scan
SN table always written
(3) max allowed error in
delay in ns. 0 -> 1.E6
PRTLEV 0.0 > 0 => diagnostic outputs
BADDISK 0.0 15.0 Disk no. not to use for
scratch files.
HELP SECTION
RLDLY
Task: This task determines the group delay difference between the R
and the L polarizations using observations of RL and LR
correlations. The data must already be calibrated for any
parallel-hand delays either through a SPLIT or through the CL
tables applied while running RLDLY. The critical parameters
are the reference antenna since only baselines to that antenna
will be used and the choice of calibration source and the
limited time range on that source. The source should have a
significant flux in the cross polarizations so that the phase
slope may be discerned. This can come from the D terms on an
unpolarized source or a real Q and U signal from a polarized
source.
This task is a special version of FRING. The apparent delay
difference will be averaged over the baselines included. Then,
unlike FRING, this task copies the CL table to a new one
correcting the phase and delay of the left-hand polarizations
for the group delay difference found. You may now turn off the
application to a CL table with APARM(2).
A new option (August 2015) allows you to select multiple
calibration scans. In this mode, the R-L delay is found for
each calibration scan individually and the correction is
written into a new SN table. No CL table is written by RLDLY
in this case. The new SN table may be interpolated to a CL
table with CLCAL (see next paragraph). The SN table is now
written even if only one calibration scan is used. Failed
solutions are written as 0.0 not blanks.
*****************************************************************
When running CLCAL on the output from RLDLY, use only one SN
table (SNVER=INVER) and set REFANT to 0. If you do not do
this, then the peculiar nature of this output (all antennas in
left have the same delay - none are zero) will be lost when
CLCAL re-references to some chosen reference antenna. All the
right-left delays will be set to zero and the RLDLY/CLCAL use
will have no effect on your data.
*****************************************************************
The answers written to the SN table are shown after all
possible reference antennas are processed for each scan. The
columns include the R-L delay, the formal error based on the
weights for the individual solutions, the rms of the multiple
delays solutions (when there is more than one reference
antenna), and the phase applied to each IF.
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 multi-source data files only:
CALSOUR....List of sources for which calibration constants are to be
determined, i.e. the calibrator sources All ' ' = all
sources; 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.
QUAL.......Only sources with a source qualifier number in the SU table
matching QUAL will be used if QUAL is not -1.
CALCODE....Calibrators may be selected on the basis of the calibrator
code:
' ' => 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. CALSOUR and QUAL, in the selection of sources
for which to determine solutions.
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, 0=> all
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, 0=> all
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 which case the task
will request that you use FREQID.
TIMERANG...Time range of the data to be used. In order: Start day,
hour, min. sec, end day, hour, min. sec. Days relative to
reference date. UNLIKE MOST TASKS, RLDLY requires real
values in this adverb to specify a modest time interval in
a scan on the calibration source. A single delay
solution is found for this interval on all examined
baselines.
BCHAN......First channel to use. 0=>all.
ECHAN......Highest channel to use. 0=>all higher than BCHAN
CHINC......Channel increment in fitting - note channels are averaged
BCHAN to BCHAN+CHINC-1, BCHAN+CHINC to BCHAN+2*CHINC-1,
etc. This reduces the memory requirements and is
suitable for delay errors that are not too large to cause
channel-to-channel loss of coherence.
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):
SUBARRAY...Subarray number to use. 0=>all.
UVRANGE....The range of uv distance from the origin in kilowavelengths
over which the data will have full weight; outside of this
annulus in the uv plane the data will be down weighted by a
factor of WTUV.
WTUV.......The weighting factor for data outside of the uv range
defined by UVRANGE.
WEIGHTIT...If > 0, change the data weights by a function of the
weights just before doing the solution. Choices are:
0 - no change weighting by 1/sigma**2
1 - sqrt (wt) weighting by 1/sigma may be more stable
2 - (wt)**0.25
3 - change all weights to 1.0
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).
Done before determining solutions.
GAINUSE....Version number of the CL (multi-source) or SN (single
source) table to apply to the data. 0 => highest.
If a CL table or SN table is written, they will always be
new tables at version highest+1.
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.
DOBAND.....(multi-source) 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......(multi-source) version of the BP table to be applied.
0 => highest; < 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).
REFANT.....The desired reference antenna for phases. Baselines to
REFANT are the only ones used in the solution. 0 causes
the task to loop over all possible REFANTs averaging the
results and applying that weighted average.
DETIME.....The minimum integration time of the data (sec);
0 => search the data to find the minimum integration
time.
The correct minimum of all baselines should be supplied.
SOLINT.....< 0 -> average over all times, multiple scans
>= 0 -> The integration time in minutes to average the
data for each solution. 0 -> large. Each scan is
broken into N equal intervals (when SOLINT is less
than the length of the scan) or 1 interval, the
length of the scan, otherwise. Solution intervals
are not carried over scan boundaries (except when
SOLINT < 0).
DOIFS......WARNING: IF THE FREQUENCY INCREMENT BETWEEN IFS THAT WILL
BE INCLUDED IN A GROUP HAS THE OPPOSITE SIGN FROM THE
FREQUENCY INCREMENT BETWEEN CHANNELS IN THE IFS OF THAT
GROUP, YOU SHOULD NOT USE THE FOLLOWING
(SET DOIFS = 0 ONLY).
Like APARM(5) in FRING:
< 0 -> use BPARM to define the grouping of IFs
= 0 -> separate solutions for each IF
= 1 -> one solution for all IFs
= 2 -> one solution for IFs 1 through NIF/2 and a second
for IFs NIF/2+1 through NIF. This may be
appropriate for the EVLA in which the first
NIF/2 are from hardware IF AC and the others are
from hardware BD.
= N -> N solutions for IFs grouped consecutively in
groups of NIF/N IFs. The task requires that
NIF/N be an integer.
BIF........First IF included when DOIFS>0 (all IFs receive the
solution found for the appropriate group of IFs, but only
BIF-EIF are used to find it).
EIF........Last IF included when DOIFS>0 (all IFs receive the
solution found for the appropriate group of IFs, but only
BIF-EIF are used to find it).
BPARM......If DOIFS < 0, group the IFs such that BPARM(i) defines
the highest IF in group i. This means that BPARM(i+1)
must be > BPARM(i) and the first BPARM not to meet this
rule defines the number of groups. Note that that really
should be the maximum IF in the data set.
APARM......(1) Minimum SNR to contribute to the solution average(s).
0 -> 5.
(2) > 0 -> do NOT write a CL table even when there is
only one calibration scan. Normally a CL table (a
new one at version N+1) is writen if (and only if)
there is one calibration scan. A new SN table is
always written. APARM(2) is set to 1 for
single-source data sets.
(3) Include only those solutions with rms less than
APARM(3) in nanoseconds. 0 -> very large.
PRTLEV.....Print flag, -1=none, 0=time every 10th time, 1=time,some
info, 2=more including the antenna signal to noise ratio,
3=a very great deal.
BADDISK....A list of disk numbers to be avoided when creating scratch
files.
EXPLAIN SECTION