; VLBAKRNG ;--------------------------------------------------------------- ;! Fringe fit data and apply calibration ;# PROCEDURE VLBI UTILITY CALIBRATION ;----------------------------------------------------------------------- ;; Copyright (C) 1995-2001; 2006 ;; 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 ;----------------------------------------------------------------------- VLBAKRNG LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC VLBAKRNG: Procedure to fringe fit and calibrate data 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 # CALSOUR Source list to fringe fit TIMERANG Time range to use. BCHAN 0.0 2048.0 Lowest channel number 0=>all FOR SPEC. LINE EXP. ONLY ECHAN 0.0 2048.0 Highest channel number FOR SPEC. LINE EXP. ONLY GAINUSE CL table to apply. REFANT Reference antenna SUBARRAY Subarray 0=>all SEARCH 0.0 1000.0 Prioritized reference antenna list - supplements REFANT SOLINT Solution interval (min) 0 => 10 min OPCODE 'ZDEL' => zero delays for more, See HELP KRING FOR SPEC. LINE EXP. ONLY CPARM for strong sources, it is only necessary to set CPARM(1) and CPARM(8). 1 min. int. time (sec) 0 => 2 8 <=0 rereference solutions this should be 1 for polarization experiments. for rest see HELP VLBAKRNG SOURCES Source list to calibrate: If sources are listed they are each calibrated with separate runs of CLCAL INTERPOL Interpolation function: '2PT','SIMP','AMBG','CUBE', 'SELF' BADDISK 0.0 15.0 Disk no. not to use for scratch files. ---------------------------------------------------------------- VLBAKRNG Type: Procedure Use: This procedure does antenna based fringe fitting using KRING and then applies those corrections using CLCAL. For more information on KRING and CLCAL see their respective HELP/EXPLAIN files. If you are doing a phase reference experiment use VLBAKRGP. Type RUN VLBAUTIL to make the VLBAKRNG procedure available. 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. 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. 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. BCHAN......First channel to use. 0=>all. ECHAN......Highest channel to use. 0=>all higher than BCHAN GAINUSE....(multisource) version number of the CL table to apply to the data. 0 => highest. REFANT.....The desired reference antenna for phases. Note that the desired refant is not required to be the primary search antenna. You should choose the REFANT to be an antenna that is present during most of the observation. SUBARRAY...Subarray number to use. 0=>all. SEARCH.....List of prioritized reference antennas to be used for fringe searching during the FFT stage. KRING constructs an internal search list to determine the order in which to perform the FFTs. This search list is constructed by first copying the elements of SEARCH. Finally, all remaining antennas antennas are appended to the search list in numerical order. You can limit the search to only the specified elements of the SEARCH list by setting CPARM(6). Only baselines where at least one antenna appears in the search list will be searched for fringes. You should explicitly order the antennas in terms of decreasing sensitivity if at all possible. SOLINT.....The solution interval. Note that this is only a recommended solution interval. The actual solution interval used by KRING will be changed in order to divide each scan evenly into an integral number of data chunks. SOLINT is in minutes; the default value (SOLINT=0) is 10 minutes. SOLINT values larger than 10 are reset to 10 minutes unless CPARM(9)>0. NB: If SOLINT > 0.75*Scan, SOLINT = Scan. OPCODE.....Solution masking to be performed _after_ fringe-fitting ' ' no masking 'ZPHS' zero phases in output SN table 'ZRAT' zero rates in output SN table 'ZDEL' zero delays in output SN table If CPARM(8)>0, OPCODE is forced = ' '. If this is not a spectral line experiment leave this as the default. CPARM......CPARM(1) and CPARM(8) are the only CPARMs that it is essential to set, for strong sources the rest can be left as default. CPARM(1)...The minimum integration time of the data (sec); 0 => 2 'VLBA' seconds It is important to get this number right to within 20 %. E.g., if you've averaged up 1 second data to 10 seconds, setting this to 10 is okay so long as there are only a very few points with shorter than 10 second integration times. If you set this to 1 second, you will regret it. CPARM(2)...The delay window FW to search (nsec) centered on 0 delay. <= 0 => full Nyquist range. [Use SOLMOD to turn off the delay search.] CPARM(3)...The rate window FW to search (mHz) centered on 0 rate. <= 0 => full Nyquist range. [Use SOLMOD to turn off the rate search.] CPARM(4)...The minimum allowed signal-to-noise ratio. <0 => 3 The SNR calculation is described in AIPS Memo 101. [You might consider setting this to 5.] CPARM(5)...Number of baseline combinations to use in the initial, FFT fringe-search (1-3). Larger values increase the point source sensitivity but reduce the sensitivity to extended sources when an accurate model is not available. 0=>3. [Solutions formed using combinations of baselines are marked with a plus for singly indirect combinations and with two pluses for doubly indirect combinations.] CPARM(6)...If CPARM(6)=1, only baselines to those antennas on the SEARCH list are searched during the FFT stage. Otherwise, other baselines are eventually searched until either fringes have been found to each antenna, or no baselines remain to be searched. CPARM(7)...If >0, RR and LL data are averaged together and only a single solution is determined for both polarizations. This is useful when reducing polarization data. CPARM(8)...If <= 0 then the phase, rate and delays will be re-referenced to a common antenna. CPARM(8)=1 is only desirable for VLBI polarization data. Using this option also forces OPCODE = ' '. CPARM(9)...If SOLINT>10 is desired, you must set CPARM(9)>0 . This is necessary to prevent accidentally requesting more memory than your computer can deliver and locking up computer. CPARM(10)..Try Hard Option. If CPARM(10)>=0, When KRING is ready to do the initial FFT-based fringe search, it will first try to initialize residual fringe-fit delay and rate solns for each antenna using an average of all good solutions found in the SN table. Only those antennas for which acceptable solutions are not found will then be FFTd to find fringes. This does not preclude the final Least Squares refinement. [20 Oct 1999, it has been reported that CPARM(10) is broken - it may trash the solutions - dont try it unless you have the time to re-run KRING if need-be.] SOURCES....Sources to calibrate. If this is left blank then all the sources are calibrated at once using the INTERPOL (i.e. CLCAL is only run once). If sources are listed then CLCAL is run once for each source using the interpolation method stated in INTERPOL. This second option is recommended, see EXPLAIN file. INTERPOL...The type of interpolation to be applied to the SN table: ' ' = linear vector interpolation with no SN smoothing. '2PT ' = linear vector interpolation with no SN smoothing. 'SELF' = Use only SN solution from same source which is closest in time. 'SIMP' = Simple linear phase connection between SN phase entries, assumes phase difference less than 180 degrees. 'AMBG' = Linear phase connection using rates to resolve phase ambiguities. 'CUBE' = As AMBG but fit third order polynomial to phases and rates. BADDISK....A list of disk numbers to be avoided when creating scratch files. ---------------------------------------------------------------- VLBAKRNG: Procedure to perform antenna based fringe fitting using KRING and then apply these corrections using CLCAL. If you are doing phase referencing use VLBAKRGP. Documenter: Amy Mioduszewski Related Programs: VLBAUTIL, KRING, CLCAL, VLBAFRNG, VLBAKRGP This should be done after solving for the instrumental phase corrections (VLBAPCOR) and before applying all the calibration and averaging (SPLIT/SPLAT). After VLBAKRNG is run it is ESSENTIAL to check the solutions in POSSM setting GAINUSE to the CL table output by VLBAKRNG. VLBAKRNG will produce the highest SN and CL table. For details on KRING and CLCAL see their HELP/EXPLAIN files. VLBAKRNG assumes: 1. there is only one FREQID 2. that all IFs should be calibrated 3. that all antennas should be calibrated 4. that the entire uv range should be calibrated 5. that the highest FG table is the one that should be applied 6. that this is a multisource file Steps in VLBAKRNG: 1. Runs KRING, which will do antenna based fringe fits. This will produce the highest SN table. 2. Runs CLCAL, with OPCODE 'CALI', SNVER output SN table from KRING; GAINVER input GAINUSE and GAINUSE = highest CL table +1. Output should be highest CL table. If SOURCES is blank then CLCAL is run only once. If SOURCES is not blank then CLCAL will be run for each SOURCE individually setting both CALSOUR and SOURCES to the same single source in the SOURCES list. This is recommended because of CLCAL is run for all the sources at once with any INTERPOL except 'SELF' then incorrect solutions may be applied for a few minutes before and after a source change. CLCAL will output the highest CL table. After VLBAKRNG is run and the solutions are checked in POSSM SPLIT or SPLAT should be run with GAINUSE set to the CL output from VLBAKRNG and DOCAL=2.