; LOCIT ;--------------------------------------------------------------- ;! fits antenna locations from SN-table data ;# Task UV Calibration ;----------------------------------------------------------------------- ;; Copyright (C) 2002, 2004-2005, 2007, 2009-2011 ;; Associated Universities, Inc. Washington DC, USA. ;; ;; This program is free software; you can redistribute it and/or ;; modify it under the terms of the GNU General Public License as ;; published by the Free Software Foundation; either version 2 of ;; the License, or (at your option) any later version. ;; ;; This program is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; ;; You should have received a copy of the GNU General Public ;; License along with this program; if not, write to the Free ;; Software Foundation, Inc., 675 Massachusetts Ave, Cambridge, ;; MA 02139, USA. ;; ;; Correspondence concerning AIPS should be addressed as follows: ;; Internet email: aipsmail@nrao.edu. ;; Postal address: AIPS Project Office ;; National Radio Astronomy Observatory ;; 520 Edgemont Road ;; Charlottesville, VA 22903-2475 USA ;----------------------------------------------------------------------- LOCIT LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC LOCIT: Task to fit antenna locations from SN table data USERID User number - ignored INNAME UV data (name). INCLASS UV data (class). INSEQ 0.0 9999.0 UV data (seq. #). 0 => high INDISK Disk unit #. 0 => any INVER -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 DPARM Controls (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 OUTPRINT Output text file base name 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 antenna arms (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. ---------------------------------------------------------------- LOCIT Type: Task Use: Fits the phases of an SN table for antenna locations. Optionally prints and plots the results. Adverbs: USERID.....User number. Ignored 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. INVER......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. DPARM......Control parameters: (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 (degrees) (5,6) Limit to hour angle range (min,max) 0 -> all (degrees) (7,8) Limit to declination range (min,max) 0 -> all (degrees) (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 wraps occur. (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 .001 for an input script for CLCOR .PAR for input to VLA PARMINATOR as increments The .VLA file is special - if one already exists 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 any non-linearities. 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 (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 BPARM(10) 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 reason. ----------------------------------------------------------------