; BSGRD ;--------------------------------------------------------------- ;! Task to image beam-switched single-dish data ;# TASK SINGLEDISH AP IMAGING OOP ;----------------------------------------------------------------------- ;; Copyright (C) 1997, 1999-2000, 2013 ;; 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 ;----------------------------------------------------------------------- BSGRD LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC BSGRD Image beam-switched data INNAME Input UV file name (name) INCLASS Input UV file name (class) Last char + and - for throws INSEQ 0.0 9999.0 Input UV file name (seq. #) INDISK 0.0 9.0 Input UV file disk unit # Cal. info for input: TIMERANG Time range to include DOCALIB -1.0 2.0 If >0 calibrate data GAINUSE CS table to apply FLAGVER Flag table version STOKES Stokes' parameter to image. 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 Projection code e.g. '-SIN' APARM 1,2,3 = RA (h,m,s) 4,5,6 = Dec (d,m,s) IMSIZE 32. 4096. Image size (X,Y) in pixels CELLSIZE 0.000001 4096. Cell size in arc seconds ROTATE Correct throw angle (deg) > 0 => in gridding < 0 => shift gridded image SHIFT (X,Y) image shift in asec REWEIGHT (1) <= 0 -> interp image = 1 -> convolved image = 2 -> weight image = 3 -> 1/sigma**2 image (2) Min convolved weight = REWEIGHT(2) * max(convolved weight) < 0 => use abs value XTYPE -2000. 2000. Conv. function type in x default spheroidal New round types - SEE HELP 100*out + temp (see help) YTYPE -2000. 2000. Conv. function type in y default spheroidal XPARM Conv. function parms for x YPARM Conv. function parms for y FACTOR Correct the beam throws by multiplying by FACTOR ORDER Baseline order (0 or 1) DPARM Parameters: (see HELP) (1) scale factor plus image over minus (0 -> 1) (2) > 0 => apply scale before differencing, else apply scale with convolution (3-4) x-pixel baseline region 1 for both images (5-6) x-pixel baseline region 2 for both images DOCAT -1. 1. > 0 => keep intermediate images BADDISK Disk drive #'s to avoid ---------------------------------------------------------------- BSGRD Task: This task will select random position beam-switched single-dish data in AIPS uv form in a specified field of view from two data sets, one for the "plus" throw and one for the "minus" throw. It makes two images, rotates the two images, removes linear baselines from each row of the images. Then it applies a convolution function to the difference of the two images to bring the plus and minus images, sign corrected, into alignment. Finally, it regrids the correc ted image into the specified coordinate system. Calibration and flagging may be applied during the selection process. If the requested image is too large the program will fail. Use SDIMG for such cases followed by OGEOM (for rotation) and BSCOR for the correction. Adverbs: INNAME.....Input single-dish data file name (name). INCLASS....Input single-dish data file name (class). The first five characters are used. The sixth character is assumed to be "+" for the plus throw and "-" for the minus throw (as produced by OTFBS). INSEQ......Input single-dish data file name (seq. #). INDISK.....Disk drive # of input single-dish data file. DOCALIB....If true (>0), then calibrate the data using information in the specified CS table. GAINUSE....Version number of the CS table to apply to the data if DOCALIB=1. 0 = highest numbered. FLAGVER....Specifies the version of the flagging table to be applied. 0 => highest numbered table. <0 => no flagging to be applied. STOKES.....Stokes' type of the desired image: 'I' => I polarization, 'Q' => Q polarization, 'U' => U polarization, 'V' => V polarization, 'RR' => right circular polarization, 'LL' => left circluar polarization, other => 'I' OUTNAME....Output file name (name). blank => INNAME OUTCLASS...Output file name (class). blank => INCLASS OUTSEQ.....Output file name (seq. #). 0 => lowest unique OUTDISK....Disk drive # of output UV file. 0 => highest with space for the file. OPTYPE.....Projection code: '-TAN' = tangent projection (optical), '-SIN' = sine projection (normal interferometer), '-ARC' = arc projection (Schmidt camera, single dish images), '-NCP' = North celestial pole (WSRT), '-STG' = stereographic projection, Those below should have latitude reference value 0.0 '-AIT' = Aitoff projection, (large field) '-GLS' = Global sinusoidal projection (large field) '-MER' = Mercator projection (large field) '-CAR' = Plate Carree ("cartesian'") '-MOL' = Molweide's (large field) '-PAR' = Parabolic (Craster - for large field) ' ' => '-SIN' See AIPS memo nos. 27 and 46 for more detail. APARM......1,2,3 are the RA as (h,m,s) 4,5,6 are the Dec, as (d,m,s) The specified position is the CENTER of the RA and DEC range before the application of the shifts (if any). Default: uv data header RA and DEC, or, if they are 0, uv data header Observed RA and Dec. If the data coordinates are relative Az-El (i.e. beam switched data), then there is no default and 0,0 would be the normal center. If APARM(4) is -0 then use APARM(4)=-0.1. IMSIZE.....(X,Y) image size in pixels. Must be even and between 32 and 4096. CELLSIZE...(X,Y) cell size in arc seconds. ROTATE.....Rotate the throw angle by ROTATE degrees CCW. Actually it just shifts the two images in elevation by throw-length * sin(ROTATE) and in azimuth by throw-length*(1-cos(ROTATE)) There are 2 methods of doing the rotation/shift: If ROTATE > 0, the initial gridding is done shifted. If ROTATE < 0, the gridded images are interpolated onto shifted images. Note that ROTATE = -355 is the same angle as ROTATE = 5, but the images are done differently. SHIFT......Probably wouldn't do what you expect: shifts the reference pixel by -SHIFT(1)/CELL(1), -SHIFT(2)/CELLS(2). The reference value is still set by APARM (see above). REWEIGHT...(1) Selects the kind of output image: <= 0 => interpolated image (convolved image divided by a convolved image with the data replaced by 1.0's). = 1 => convolved image of data. = 2 => convolved image with data replaced by 1, i.e an image of the data weights (sum of input data weight * uniform weight correction * convolving function at each cell) = 3 => image of K/sigma**2 for an interpolated image assuming the input weights are K/sigma**2 for the data samples (2) Minimum convolved weight (image with data replaced by 1.0's) to remain unblanked = REWEIGHT(2) * max(convolved weight). < 0 => use abs(convolved weight) compared to abs(REWEIGHT(2)*max(convolved weight)) 0 => -0.01. for interpolation output and no blanking for convolution and weight outputs XTYPE......Convolution function type in X-direction 1=Pillbox, 2=exponential, 3=Sinc, 4=Exp*Sinc, 5=Spheroidal, 6=Exp*BESSJ1(x)/x = 0 or > 6 (& < 11) -> 5. 11 - 16 => circular functions in radius corresponding to 1 - 6 types above; YTYPE, YPARM are ignored. If XTYPE < 0, then abs(xtype) is used and some of the XPARM values are assumed to be in arc seconds rather than cells. See HELP UV1TYPE through HELP UV6TYPE for details. There are two convolutions, first to the + and - images and then from the corrected az-el image to an ra-dec image. XTYPE = 100*xtype(2) + xtype(1). Same for YTYPE. Note that both xtype(i) have to have the same sign. YTYPE......Convolution function type in Y-direction XPARM......Array containing parameters for XTYPE. See HELP UVnTYPE when n=convolution type. XPARM(5) is number samples of convolution function used per image cell for circular functions - 100 is used for X/Y separable functions (types 1-6). XPARM for the second gridding type is the same as for the first if they are of the same type. Otherwise, the second gridding uses default values for XPARM. YPARM......Array containing parameters for YTYPE. FACTOR.....Change the beam throws by FACTOR. ORDER......Order of baseline removed from each row of each image. Only 0 and 1 are allowed. DPARM......Parameters: (1) The plus beam may be scaled by DPARM(1) wrt the minus beam. (You may need to use IMFIT to determine this ratio. Be sure to fit a baseline as well as a Gaussian.) 0 => 1. (2) The ratio may be applied at two different stages: if DPARM(2) > 0, the images are scaled before they are differenced. Otherwise, the scaling is done through a modification of the convolution function. (3) Start x pixel of both images to use for the first of 2 baseline regions. 0 => 1. N.B. this applies after BLC(1) has been applied. (4) End x pixel of both images to use for first baseline region. 0 => all (not a good default). N.B. above N.B. (5) Start x pixel of both images to use for the second of 2 baseline regions. 0 => none. N.B. above N.B. (6) End x pixel of both images to use for second baseline region. 0 => all (an okay default). It has been found by experimentation that it is essential to use the same baseline regions for both images. DOCAT......> 0 => keep the intermediate images (BSGRD+, BSGRD-, BSROT+, BSROT-, and BSGCOR) as well as the final output image. <= 0 => delete these asap. BADDISK...Disk drive #'s to avoid for scratch files ----------------------------------------------------------------