; CVEL ;--------------------------------------------------------------- ;! shifts spectral-line UV data to a given velocity ;# TASK SPECTRAL CALIBRATION VLA VLBI UV ;----------------------------------------------------------------------- ;; Copyright (C) 1995-1999, 2008-2010, 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 ;----------------------------------------------------------------------- CVEL LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC CVEL Task to shift spectral line data to a given velocity 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 # SOURCES Source list to shift, other sources will be passed unshifted. Ignored for single source files. '*' or ' ' => all; QUAL -10.0 Source qualifier to shift, Sources with other quals will be passed unshifted. -1 => no selection by qual TIMERANG Time range to shift SELBAND Bandwidth to select (kHz) SELFREQ Frequency to select (MHz) FREQID 0.0 Freq. ID to select (1 only) SUBARRAY 0.0 1000.0 Subarray, 0=>1 FLAGVER Flag table version DOBAND -1.0 10.0 If >0 apply bandpass cal. Method used depends on value of DOBAND (see HELP file). BPVER Bandpass table version GAINUSE CL table version which contains the time/antenna dependent frequency offsets. 0 => 1. APARMS(1:6) will define the velocity parameters needed for single source files. The parameters you define here will override any of those set with ALTDEF. If any of APARM(1)-(6) are set CVEL will assume all are set. These are ignored in the case of multi-source files, you should use SETJY for them. APARM (1) => for single source file the velocity of a given pixel (m/s). (2) => the pixel to which APARM(1) refers. (3) defines the velocity type 0 => LSR, 1 => HELIO (4) the velocity definition: 0 => optical, 1 => radio (5) aparms 5 & 6 define the rest frequency of the line in Hz; the value used is the sum of APARM(5) + APARM(6). See helpfile. (7) not used now (8) if > 0 then do not print messages about large channel shifts, used if deliberately want a large shift. (9) 0 => not smooth spectra while shifting >0 => smooth AC spectra by Hanning >1 => smooth XC spectra by Hanning also (10) 0 = trust CVEL 1 = Earth center 2 = Low antenna 3 = High antenna BADDISK 0.0 9999.0 Disks to avoid for scratch ---------------------------------------------------------------- CVEL Task: Shift a uv spectral line data set in frequency space. The purpose of the task is to shift all spectra to a given velocity; this will correct data observed with a fixed frequency for the effects of the Earth's rotation and its motion within the Solar System and towards the Local Standard of Rest. CVEL will work on both single and multi-source files. For multi-source files the velocity to which the spectra are to be shifted should be entered into the source (SU) table using the task SETJY, this should be done for each source you wish to shift. You then specify those sources with the SOURCE command in CVEL, all other sources will be written to the output uv file with their spectra unshifted. For single source files the necessary velocity data are passed to the task using APARM(1) - APARM(6) The shift that is reported is a shift of the profile with respect to the channels, i.e. a shift of -0.4 will shift the profile to the left. The task will attempt to determine if it is processing data from the VLBA correlator by examining the ANAME keyword in the AN(tenna) table. If it is 'VLBA' then CVEL assumes that all data have been fringe-rotated to the same reference point (the centre of the Earth) and will determine the velocity correction accordingly. NOTE: this task optionally applies bandpass and flag tables to the data but does not apply SN/CL calibration tables, polarization, baseline-cals, etc. Run SPLIT first if these operations are desired. 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....Drive # of output UV file. 0 => highest with space for the file. SOURCES....Source list to shift. All sources named will be shifted to the velocity found in the SU table. All other sources will be passed to the output file unshifted. Ignored for single source files. Some rules apply: '*' or ' ' = all; a "-" before a source name means shift all except ANY source named. QUAL.......Only sources with a source qualifier number in the SU table matching QUAL will be used. If QUAL is -1, then selection by a qualifier is ignored. Selection by a qualifier is ignored for single source file also. TIMERANG...Time range of the data to be shifted. In order: Start day, hour, min. sec, end day, hour, min. sec. Days relative to ref. 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. For data which contain multiple bandwidths/frequencies the task will insist that some form of selection be made by frequency or bandwidth. 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. FREQID.....Frequency identifier to select. CVEL will process only one frequency identifier, ignoring any others. 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 that case, the task will request that you use FREQID. SUBARRAY...Subarray number to use. 0=>1 FLAGVER....specifies the version of the flagging table to be applied. 0 => highest numbered table. <0 => no flagging to be applied. 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......Specifies the version of the BP table to apply. GAINUSE....version number of the CL table from which CVEL will extract the tima and antenna dependent frequency offsets. For instance, if some attempt was made to occasionally correct for the doppler offsets these offsets would be recorded in the CL table. For CVEL to determine the true observing frequency at any given time it must add up the reference freq. in the catalogue header, the IF offset freq for IF > 1, the peculiar source freq. offset and the time and antenna dependent freq. stored in the CL table. If the data have been SPLIT, or CLCAL has generated a new CL table there is no guarantee that the time dependent offsets will be taken into account. 0 => 1 APARM......Control information: The control information is used to specify the necessary velocity parameters for single source files. The parameters you define here will override any of those you set with ALTDEF. If any of APARM(1) to (6) are set then the task assumes that all are set. APARM(1): the velocity of a given pixel (channel) in the spectrum (m/s). APARM(2): the pixel (channel) to which APARM(1) refers. APARM(3): the velocity type, 0 => LSR, 1 => heliocentric APARM(4): the velocity definition, 0 > optical, 1 => radio APARM(5) & APARM(6): define the restfrequency of the molecular transition in Hz; the value used is the sum of APARM(5) and APARM(6) (need the extra precision). APARM(7): not used now APARM(8): if > 0 then do not print messages about large channel shifts, used if deliberately want a large shift. APARM(9): 0 => not smooth spectra while shifting >0 => smooth autocorrelation spectra by Hanning >1 => smooth cross-correlation spectra by Hanning as well. It is strongly recomended to smooth spectra in the case of strong narrow features. Otherwise various ringing effects including 180 degree phase jumps between adjacent channels can occur. APARM(10): The correlator must shift the frequency of one or both antennas in a baseline to the same in order to correlate. The VLBA coorelators among others shifts both to the Earth's center. The JIVE EVN shifts the low numbered one to the high numbered one. Others the opposite. If you know what this about and know what your correlator did then set this parameter: 1 => Earth center 2 => low numbered 3 => high numbered The default sets 1 for VLBA, 3 for EVN, rest 2 based on the array name in the antenna file. NOTE WELL - THIS BUSINESS MEANS THAT IT IS VERY BAD TO RENUMBER ANTENNAS IF THAT RENUMBERING CHANGES THEIR ORDER UNLESS THE EARTH CENTER IS THE CORRECT CHOICE FOR THIS ARRAY. BADDISK....A list of disks on which scratch files are not to be placed. This will not affect the output file. ----------------------------------------------------------------