AIPS HELP file for LOCIT in 31DEC22
As of Tue Nov 28 23:26:58 2023
LOCIT: Task to fit antenna locations from SN table data
INNAME UV data (name).
INCLASS UV data (class).
INSEQ 0.0 9999.0 UV data (seq. #). 0 => high
INDISK Disk unit #. 0 => any
INVERS -1.0 255.0 SN table version
SOURCES Source list
TIMERANG Time range to list
SELBAND Bandwidth to select (kHz)
SELFREQ Frequency to select (MHz)
FREQID Freq. ID to select.
None selected => 1.
BIF 0.0 100.0 Lowest IF number 0=1
EIF 0.0 100.0 Highest IF number
STOKES Stokes to use
ANTENNAS Antennas to fit
SUBARRAY 0.0 1000.0 Subarray, 0=>1
REFANT 0.0 90.0 Reference antenna
(1) > 0 => difference method
(2) > 0 => omit K term
(3,4) Elevation range (deg)
(5,6) HA range (deg)
(7,8) Dec range (deg)
(9) > 0 Difference 2 IFs
(10) > 0 solve for slope
PRTLEV 0.0 3.0 Print level - 0 normal
Output text file base name
DOOUTPUT -1.0 > 0 => include previous
solutions from file
BPARM (1) antennas/plot page
(2) > 0 -> plot R-L
(3) Phase plot min
(4) Phase plot max
(5) Scale plotted points
(6) Point type
(7) Line type
(8) Degree of crowding
(9) > 0 plot solutions on
(10) scale (9) plot
DOTV -1.0 1.0 > 0 -> plot to TV
GRCHAN 0.0 7.0 Graphics channel to use
BADDISK Disk to avoid for scratch.
Use: Fits the phases of an SN table for antenna locations.
Optionally prints and plots the results.
INNAME.....UV file name (name). Standard defaults.
INCLASS....UV file name (class). Standard defaults.
INSEQ......UV file name (seq. #). 0 => highest.
INDISK.....Disk unit #. 0 => any.
INVERS.....SN table version number 0=highest.
SOURCES....List of sources to be listed. ' '=> all; if any starts
with a '-' then all except ANY source named.
TIMERANG...Time range of the data to be listed. In order:
Start day, hour, min. sec, End day, hour, min. sec
Days relative to reference 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, 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 LOCIT. 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. If neither SELBAND, SELFREQ
nor FREQID are specified then the first FQ id in
the FQ table (usually 1) will be used.
BIF........Lowest IF to use.
NOTE to VLA users: IF=1 corresponds to the VLA
AC ifpairs and IF=2 corresponds to the BD ifpairs.
EIF........Highest IF to list. 0 => Highest
STOKES.....'RR' or 'R' use only right hand
'LL' or 'L' use only left hand, else use both if present.
ANTENNAS...A list of the antennas to fit. If any number is negative
then all antennas listed are NOT desired and all others
are. All 0 => fit all except REFANT.
SUBARRAY...Subarray number to list. 0=>1.
REFANT.....Antenna that is asumed to be fixed --- all fits are
relative to this antenna. Note that you may use no
reference antenna if you wish - effectively saying that
the reference antenna phases are all zero which they will
be if the same REFANT was used in CALIB. The difference
method has no use for a REFANT.
(1) > 0 => use the method in which consecutive
observations are differenced.
(2) > 0 => do not do the K term
(3,4) Limit to elevation range (min,max) 0 -> all
(5,6) Limit to hour angle range (min,max) 0 -> all
(7,8) Limit to declination range (min,max) 0 -> all
(9) > 0 => use the method in which IF 2 is differenced
with IF 1. This is useful if the antenna locations
are poorly known since it depends on the small
frequency difference between the two IFs rather than
the larger absolute frequency of the IFs. Note that
this halves the number of data points and makes the
errors much larger, but is essential if the antenna
locations are so poorly known that multiple phase
(10) > 0 => solve for a linear slope in phase with time.
Otherwise assume that the phase is roughly constant
after the antenna locations are corrected.
PRTLEV.....Print level used for debugging problems. 0 normal.
OUTPRINT...Disk text file name to use for output text files
This is used as a base name to which is appended
.FIT for all sorts of things depending on PRTLEV
.VLA for corrections to be made (actually array name fo
VLA, EVLA, VLBA, etc)
.001 for an input script for CLCOR
.PAR for input to VLA PARMINATOR as increments
The .VLA file is special - if one already exists and
DOUTPUT > 0, it is read and the current corrections added
to any found in the file. The old file is renamed before
a new one containing the accumulated corrections is
written. The .FIT and .001 files only contain the
current corrections, while the .VLA and .PAR files
contain the accumulated corrections.. This is done in
case one is running the fitting more than once to resolve
DOOUTPUT...> 0 => use any pre-existing OUTPRINT. file as
<=0 => append new solutions to old files without adding
the previous solutions.
BPARM......(1) Number of antennas plotted per page. 0 -> no plots.
(2) > 0 -> plot R-L rather than R and L separately
(STOKES must not be 'RR' or 'LL')
(3) Fixed plot range minimum in degrees (see below).
(4) Fixed plot maximum in degrees.
If BPARM(4) > BPARM(3) do a fixed scale plot from
BPARM(3) to BPARM(4), discarding any points outside
the range. If BPARM(4) < BPARM(3), do a fixed scale
plot from BPARM(4) to BPARM(3) except that, if there
are data outside this range for a particular plot,
allow that plot to self-scale to the larger range.
If BPARM(4) = BPARM(3), self-scale all plots.
(5) Plot points scaled by BPARM(5) 0 -> 1
(6) Point plot symbol:
1: Plus sign 12: Five pointed star
2: Cross (X) 13: Star of David
3: Circle 14: Seven-pointed star
4: Box 15: Eight-pointed star
5: Triangle 16: Nine-pointed star
6: Diamond 17: Ten-pointed star
7: Pentagon 18: 11-pointed star
8: Hexagon 19: 12-pointed star
9: Septagon 20: 13-pointed star
10: Octagon 21: 14-pointed star
11: Nine-gon 22: Plus with gap
23: Vertical line
24: Cross (X) with gap
(7) Do with connected lines: 0 no line, 1 direct
connection, 2 steps, -1 no points, connected line,
-2 no points, stepped line
(8) = 1 -> plot polarizations together
= 2 -> plot IFs and polarizations together
In both cases, color is used to differentiate what is
plotted. If there are <= 4 things, then the graphics
plane colors are used. If > 4, then 3-color plotting
(9) > 0 => make a plot of the answers as a function of
location along each arm
> 1.5 => plot the good answers only
(10) Scale the data points of the BPARM(9) plot by
DOTV.......> 0 => make the plot(s) on the TV, else make plot files.
GRCHAN.....Graphics channel to use when DOTV > 0. 0 -> multiple
which makes more readable plots.
BADDISK....Disk numbers to avoid for scratch files. Scratch
files may be created by the sorting routines if
calibration or flagging is applied.
The data to be used for LOCIT needs to be taken for the purpose of
fitting antenna locations. Point-source calibrators all over the sky
must be observed one after another, preferably with large shifts in
hour angle and declination between scans. The choice of REFANT is
significant and a single station should be used at all times, even
though its antenna number will change occasionally.
The DPARM(1) = 1 method implements an old Cal Tech algorithm in which
the antenna/atmosphere phase was assumed not to change between
adjacent scans. The antenna phases of adjacent scans are differenced
as are the derivatives of phase wrt antenna location at the two scans.
The phase slope with time and the average phase offset are not
determined since they are assumed zero in this method. The method
does limit the systematic wanderings of phase but seems to produce
somewhat noisier solutions for well-behaved antennas for some unknown