; ACFIT ;--------------------------------------------------------------- ;! Determine antenna gains from autocorrelations ;# TASK CALIBRATION VLBI SPECTRAL ;----------------------------------------------------------------------- ;; Copyright (C) 1995, 1997, 2000, 2004, 2006, 2009 ;; 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 ;----------------------------------------------------------------------- ACFIT LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC ACFIT Task to determine antenna gains from autocorrelations 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 # Data Selection CALSOUR Sources to use to determine gains. 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 select SUBARRAY 0.0 1000.0 Subarray, 0=>1 ANTENNAS Antennas to select Template file IN2NAME Template UV file name (name) IN2CLASS Template UV file name (class) IN2SEQ 0.0 9999.0 Template UV file name (seq.#) IN2DISK 0.0 9.0 Template UV file disk unit # REFANT Reference antenna. Control options DOCALIB -1.0 101.0 > 0 calibrate data & weights > 99 do NOT calibrate weights GAINUSE CL (or SN) table to apply FLAGVER Flag table version SOLINT Solution interval DOBAND If > 1 apply BP correction BPVER BP table version to write SMOOTH Smoothing function. See HELP SMOOTH for details. Does not apply to template spectrum. BCHAN 0.0 2048.0 Start channel for fit 0=>1 ECHAN 0.0 2048.0 Stop channel for fit 0=>all APARM Control information: (1) Polynomial degree for source spectrum baseline (2) Polynomial degree for template spect. baseline (3) Rpol sensitivity of template antenna (Jy/K). Use this if only one polzn in data. (4) Lpol sensitivity of template antenna (Jy/K) (5) Minimum allowed relative gain value, 0 => 0 (6) Maximum allowed relative gain value, 0 => all (7) Maximum allowed relative gain error, 0 => all (8) Print level, 1=> print gains. (9) >0 => Baseline independent fit. (10)>0 => write out AC data after baseline removed BPARM Array of start and stop channel numbers for baseline fitting on source spectrum. CPARM Array of start and stop channel numbers for baseline fitting on template spectrum. XPARM Array of Rpol Tsys(IF) of template scan. 0 => 1.0. Use XPARM if only one polzn in database. YPARM Array of Lpol Tsys(IF) of template scan. 0 => 1.0 SNVER -1.0 46655.0 Output SN table, 0=>new table OUTNAME Output UV file name (name) OUTCLASS Output UV file name (class) OUTSEQ 0.0 9999.0 Output UV file name (seq. #) OUTDISK 0.0 9.0 Output UV file disk unit # BADDISK 0.0 9999.0 Disks to avoid for scratch ---------------------------------------------------------------- ACFIT Task: To calibrate spectral line data using total-power spectra. The method used is based on the 'template' spectrum method developed for the calibration of spectral line VLBI data. You should generate a 'template' spectrum, i.e. a high-quality spectrum from a scan taken at a sensitive antenna at a reasonable elevation. Use SPLIT and UVCOP to write this spectrum into a seperate uv-file. ACFIT will then fit the template to all other total-power spectra from all antennas (using a linear least-squares algorithm) and generate an SN table which contains the relative gains of the antennas as a function of time. These can be translated to absolute gains simply by multiplication by the measured Tsys and Gain of the template antenna. 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 to be used to determine gains. All ' ' = all sources; a "-" before a source name. means all except ANY source named. If the data file is a single source file no source name need be specified. 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 overide 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 selected. In order: Start day, hour, min. sec, end day, hour, min. sec. Days relative to ref. date. SUBARRAY...Subarray number to select. 0=>1. ANTENNAS...A list of the antennas for which gains are to be determined.. If any number is negative then all antennas listed are NOT to be used and all others are. The following specify the template spectrum file. IN2NAME....Template UV file name (name). Standard defaults. IN2CLASS...Template UV file name (class). Standard defaults. IN2SEQ.....Template UV file name (seq. #). 0 -> highest. IN2DISK....Disk drive # of template UV file. 0 => any. REFANT.....Antenna to select from the template file whose autocorrelation spectrum is to be used as the template, useful if have multiple antennas in the template file. 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). The calibration is applied prior to the gain determination. GAINUSE....version number of the CL table to apply to multisource files or the SN table for single source files. 0 => highest. FLAGVER....specifies the version of the flagging table to be applied. 0 => highest numbered table. <0 => no flagging to be applied. SOLINT.....the interval (mins) over which to average the data before solving for the gains. (0 => scan) DOBAND.....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......the version of the BP table to use. (0 => highest) SMOOTH.....Specifies the type of spectral smoothing to be applied to a uv database . The default is not to apply any smoothing. The smoothing function is only applied to the spectra from the main database, it is not applied to the template spectrum. That should be smoothed by SPLIT if so desired. 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). BCHAN......Start channel of region of spectrum to be used for for fit, 0 => 1. ECHAN......End channel of region of spectrum to be used for for fit, 0 => all. APARM......Task enrichment parameters. (1) => degree of polynomial to be removed from the source spectrum. The channel ranges over which to determine polynomial baseline are set by BPARMS. (2) => Degree of polynomial to be removed from the template spectrum. Channel range specified in CPARM. (3) => The gain of the RHC polzn of the template antenna. (Jy/deg), 0 => 1.0 If only one polzn is present in the database use APARM(3) to specify the antenna gain. (4) => The gain of the LHC polzn of the template antenna (Jy/deg), 0 => 1.0. Ignored if only one polzn in data. (5) => Minimum relative gain accepted (before multiplication by Tsys and Jydeg. 0 => 0 (6) => Maximum relative gain accepted (before multiplication by Tsys and Jydeg. 0 => all (7) => Maximum percentage relative gain error accepted, 0 => all. Recommend APARM(7)=20, i.e. 20% (8) => print level, 0 => hardly anything 1 => relative gain found for each antenna and each averaging interval. 2 => gory details (9) => Subtract baselines then fit gain => 0 Baseline-independent fit => 1. If using a baseline-independent fit then BCHAN and ECHAN should include channels containing no emission. (10) => If > 0 and APARM(9)=0 then will write out the total power spectra with spectral baselines removed to an output file given by OUTNAME etc. BPARM......Array of start and stop channels to use for fitting a polynomial to any residual spectral baseline. Order of polynomial is given by APARM(1). If all 0, no residual baseline will be removed. CPARM......Same as BPARM but used for the template spectrum Order of polynomial is given by APARM(1). If all 0, no residual baseline will be removed. XPARM......Array of RHC Tsys(IF)(K) - system's temperature of the template scan for different IFs. 0 => 1.0. If only one polzn in the database use XPARM to specify the Tsys values. YPARM......Array of LHC Tsys(IF)(K) - system's temperature of the template scan for different IFs. 0 => 1.0. If only one polzn in the database then YPARM will be ignored. OUTNAME....Output UV file name (name). Standard defaults. OUTCLASS...Output UV file name (class). Standard defaults. OUTSEQ.....Output UV file name (seq. #). 0 => highest. OUTDISK....Drive # of output UV file. 0 => highest with space for the file. BADDISK....A list of disks on which scratch files are not to be placed. This will not affect the output file. ----------------------------------------------------------------