; BPWAY ;--------------------------------------------------------------- ;! Determines channel-dependent relative weights ;# Task UV CALIBRATION VLA ;----------------------------------------------------------------------- ;; Copyright (C) 2014 ;; 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 ;----------------------------------------------------------------------- BPWAY LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC BPWAY: Determines channel-dependent relative weights 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 # 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 # OPTYPE 'SORC' else 'SCAN' SOURCES Source name QUAL -10.0 Calibrator qualifier -1=>all CALCODE Calibrator code ' '=>all TIMERANG Time range to use FREQID Freq. ID to select. SUBARRAY 0.0 1000.0 Sub-array, 0=>all DOCALIB -1.0 101.0 > 0 calibrate data & weights > 99 do NOT calibrate weights GAINUSE CL (or SN) table to apply DOPOL -1.0 10.0 If >0.5 correct polarization. PDVER PD table to apply (DOPOL>0) BLVER BL table to apply. FLAGVER Flag table version DOBAND -1.0 10.0 If >0.5 apply bandpass cal. Method used depends on value of DOBAND (see HELP file). BPVER Bandpass table version SMOOTH Spectral smoothing function Dangerous here - see help. BIF Lower IF to include EIF Upper IF to include ICHANSEL Array of start and stop chan numbers, plus a channel increment and IF to be used to select channels to sum to find average spectral rms. FPARM (1) > 0 rolling T buffer to find time rms F(1) times (2) Normal time interval between samples (sec) IMPORTANT TO BE ~RIGHT (3) Flag any visibility amp > F(13) before time rms 0 -> 1.E6 (4) Smoothing type (5) Smoothing width (min) (6) Smoothing support (min) (7) Minimum weight factor (8) Maximum weight factor (9) > 0 -> average Stokes FQCENTER >= 0 -> center frequency axis ---------------------------------------------------------------- BPWAY Task: This task examines data, one scan at a time. In each scan, the task finds the rms versus time for each baseline over time intervals, which are usually fairly short, one polarization and one spectral channel at a time. This operation is done with a moving window to determine the rms at the center of the window. The spectra of rmses are normalized and then written to a table where they are sorted, smoothed over time, and then re-sorted to time order. These time smoothed rmses are then used to set the weights of the data written to a new data set. This data set is written in uncompressed form to avoid loosing all the weights just computed. Note that any calibration, particularly bandpass, should be applied to the data either before or in this task. 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. 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....Disk drive # of output UV file. 0 => highest with space OPTYPE.....'SORC' => do one source at a time. If > 1 source, then data will end up out of time order. Otherwise, do one scan at a time. The result may be noisier but will beter reflect and real changes in the weights and the output data will still be in time order. SOURCES....Sources to be copied. ' '=> all; if any starts with a '-' then all except ANY source named. QUAL.......Qualifier of sources to be copied. -1 => all. CALCODE....Calibrator code of sources to copy. ' '=> all. TIMERANG...Time range of the data to be copied. In order: Start day, hour, min. sec, end day, hour, min. sec. Days relative to ref. date. FREQID.....Frequency identifier to select (you may determine which is applicable from the OPTYPE='SCAN' listing produced by LISTR). This task does not use SELBAND or SELFREQ and is easily able to accomodate all Freq IDs. <= 0 -> all SUBARRAY...Sub-array number to copy. 0=>all. 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). GAINUSE....version number of the CL table to apply to multi-source files or the SN table for single source files. 0 => highest. 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. FLAGVER....specifies the version of the flagging table to be applied. 0 => highest numbered table. <0 => no flagging to be applied. Keep track of your FG table versions to be certain that you are using all of the flags that you intend to use. 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. IMAGR uses DOBAND as the nearest integer; 0.1 is therefore "false". BPVER......Specifies the version of the BP table to be applied 0 => highest numbered table. <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. NOTE: SMOOTH IS FAIRLY DANGEROUS IN THIS CONTEXT. Applying SMOOTH because it was applied in BPASS must still be done. SMOOTHING after BP application will smooth out real structure in the spectral shape of weights. If you realy need SMOOTH to remove ringing from narrow-band signals, run SPLAT on the data to apply the SMOOTH and then set SMOOTH=0 for later work. 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). BIF........First IF included in operation EIF........Last IF included in operation ICHANSEL.. Array of start, stop, and increment channel numbers plus an IF used for channel selection in the averaging to compute a normalized rms. Up to 20 sets if channels/IF may be entered. The first having ICHANSEL(2,i) <= 0 terminates the list. ICHANSEL(4,i) is the IF number, with <= 0 meaning all IFs. If an IF has no ICHANSEL set for it, then the inner 3/4 of the channels will be used. FPARM......(1) Number of times to be included in the time rms. We recommend an odd number and < 3 -> 3. (2) Normal interval between samples in seconds. The program will not do intervals longer than 2 * FPARM(1) * FPARM(2). 0 -> 10 secs IT IS IMPORTANT TO HAVE THIS ABOUT RIGHT. If it is too short, in particular, then data samples that belong in the same bin (time interval) may end up in different bins. This happens most often when data have been time averaged after selective flagging. Set it to somewhat less than the averaging time - if observations at XINT are averaged over N times, set FPARM(2) = (N-0.5) * XINT. (3) Examine the data before doing any other checks and flag all samples > FPARM(3) Jy. 0 -> 1.E8. (4) Code for type of smoothing function: 1: Boxcar, 2: Gaussian, 3: Exponential, 4: Linear, 5 Median . 0 -> 1 (5) FWHM for Gaussian, exponential, linear in minutes. 0 -> 10 (6) Full support size for smoothing function in minutes, the function has value 0.0 outside +- FPARM(6)/2 from the time being evaluated. 0 -> 10 for box, median; 0 -> 3, 4, 2 * FPARM(5) for Gaussian, exponential, and linear, resp. (7) Minimum weight factor: the existing weight is multiplied by 1/rms^2 so this is equivalent to setting a maximum (normalized) rms. 0 -> 0. (8) Maximum weight factor: the existing weight is multiplied by 1/rms^2 so this is equivalent to setting a minimum (normalized) rms. 0 -> 10000. NOTE: these minimum and maximum rms are applied before the smoothing to keep really extreme values from affecting the smoothed values excessively. (9) If > 0, average the rms values over polarization before smoothing. FQCENTER,..> 0 => Change frequency axis reference pixel to Nchan / 2 + 1 else => do not change reference pixel ----------------------------------------------------------------