; HAFIX ;---------------------------------------------------------------------- ;! Recomputes u,v,w when time is hour angle (UVdata is output of TI2HA) ;# Task UV ;----------------------------------------------------------------------- ;; Copyright (C) 2007, 2009, 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 ;----------------------------------------------------------------------- HAFIX LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC HAFIX Task to recompute u,v,w when time is hour angle. 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 -1.0 9999.0 Output UV file name (seq. #) OUTDISK 0.0 9.0 Output UV file disk unit #. SHIFT Position shift(RA,Dec) asec. UVFIXPRM Array geometry 1 0=VLA, 1=VLB, 2=GMRT, 3=other 1 for EVLA 2 => subarray number 0=>all 3-4=>array center bx, meters 5-6=>array center by, meters 7-8=>array center bz, meters Time and frequency info. 11 => UT1-UTC (sec) 12 => IAT-UTC (sec). 0: use accumulated leap seconds. 13 => time shift used for the correction, in second 14 => Freq (Hz) If .LE.0 use value in AN file 15 OB table number 0 => 1 16 Number of the orbiting antennas; 0=>there is no an orbiting antenna 17 Besselian epoch of data 18 differential aberration 0 => include 1 => not include 20 > 0 do not compute u,v,w OPTYPE ' '=>UVW is recalculated for IAT+UVFIXPRM(13) 'DELT'=>UVW_old+UVW(IAT+DT) -UVW(IAT) DT = UVFIXPRM(13) FQCENTER >= 0 -> center frequency axis ---------------------------------------------------------------- HAFIX Type: Task Use: This task is a modification of UVFIX design to diagnose a possible time shift problem at the original UV data. The input UVdata are the output of the task TI2HA, which converted original IAT time into hour angle. This task reads a row of the input data, stores the original U,V,W, converts the given hour angle back to IAT time, recalculates U,V,W for this time and for the shifted time and finally adds the difference of the two sets of U,V,W to the original U,V,W. The idea is to correct the error at U,V,W because a possible error at time. The user can calculate (under control of OPTYPE) only one time shift UVW output. This optin is usefull to see by eyes the effect of the time shift. ************************************************************** * This task includes many options left from the UVFIX task * * They can be used later on the user's need * ************************************************************** 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 unique. OUTDISK....Disk drive # of output UV file.0 => highest w room. SHIFT......Desired position shift in the tangent point coordinates in arcseconds at the source. The new tangent point coordinates will be RA' = RA + SHIFT(1)/COS(DEC) and DEC' = DEC + SHIFT(2) where all coordinates are in arcseconds. NOTE: SHIFT(1) changed meaning to be like other shifts in AIPS 2003-02-20. UVFIXPRM......THE ONLY PARAMETER USED NOW IS UVFIXPRM(13)!!!!!!. 1 => now normally ignored. If the array center is to be changed, then one must set this parameter to 3. 2 => subarray number, 0 => loop over all. 3+4 => array BX, meters. (ONLY if UVFIXPRM(1)=3) Default is value in AN file 5+6 => array BY, meters. (ONLY if UVFIXPRM(1)=3) Default as BX. 7+8 => array BZ, meters. (ONLY if UVFIXPRM(1)=3) Default as BX. Here X is in the direction of the intersection of the meridian of the reference location (long=0 for earth centered) and the equator; Y is 90 deg. EAST along the equator from X; Z is in the direction of the N. pole. Note that: BX = UVFIXPRM(3) + UVFIXPRM(4), BY = UVFIXPRM(5) + UVFIXPRM(6), BZ = UVFIXPRM(7) + UVFIXPRM(8). The addition of two parameters allows the coordinates to be specified with more precision than a single adverb allows; on a 32-bit machines adverb values are only accurate to 7 significant digits. The array center is changed only if the two values are not zero - set set 10**-20 if 0 is desired. 11 => UT1-UTC in seconds. Default = value in AN file. (Use it!) 12 => IAT-UTC in seconds. Default = value in AN file. (Use it!) Typically = year-1961 which is OK until mid-1982; after 1982 it is off 1 (or more) second(s). Accurate values for both UT1-UTC and IAT-UTC can be obtained from USNO Bulletin no. 7. If this parameter is 0, HAFIX uses the value returned by the routine LPSEC. LPSEC will have to be updated everytime a leap second is added. The value as of July 1, 1993 was 28 seconds. ------------------------------------------------------------ 13 => The time shift, in seconds This is the only parameter used practically now. ------------------------------------------------------------ 14 => Frequency in Hz. If <= 0, the value in the AN, FQ, and SU files will be used. 15 OB table number; 0 => 1 16 The antenna number of the orbiting antenna; 0=>there is no an orbiting antenna; It is assumed that there is at most one orbiting antenna. Parameters #15 and #16 are not used for conventional (ground based) interferometry. Thus zeros are normally desirable. 17 Besselian epoch of data. When converting B1950 to J2000, the coordinates must first be converted to the observation date and then converted to J2000. 0 => 1979.3 which is okay for most VLA data. 18 0 => include differential aberration(Lorentz factor) 1 => not includes differential aberration(Lorentz factor) 20 > 0 => Do not recompute U, V, W. Users of the ATCA may want this option since the recomputation changes -NCP to -SIN projection for the U,V,W coordinates. Under all other circumstances, this option is not desirable. OPTYPE...' ' => recalculate UVW for the IAT time recalculated from the given hour angle and corrected by UVFIXPRM(13) 'DELT' => correct the existing UVW by the difference of U,V,W calculated for the two IAT times: IAT1-is the recalculated IAT from the given hour angle IAT2-is IAT1 + plus UVFIXPRM(13) FQCENTER,...> 0 => Change frequency axis reference pixel to Nchan / 2 + 1 else => do not change reference pixel ----------------------------------------------------------------