; FITAB ;--------------------------------------------------------------- ;! writes images / uv data w extensions to tape in FITS format ;# TASK TAPE FITS UV IMAGE-UTIL ;----------------------------------------------------------------------- ;; Copyright (C) 1999-2000, 2003-2004, 2008 ;; 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 ;----------------------------------------------------------------------- FITAB LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC FITAB: Task to write maps or uv data as tables on a FITS tape DOALL -1.0 1.0 1 (T) do all, -1 (F) do 1st. INNAME Image name(name). Standard. INCLASS Image name(class). Standard. INSEQ 0.0 9999.0 Image name(seq. #). INDISK 0.0 9.0 Disk drive #. 0 => any INTYPE File type. Blank => any OUTTAPE 0.0 9.0 Tape drive #. 0 => 1 DATAOUT Disk file name DOEOT -1.0 1.0 1 (T) go to end tape first. FORMAT 0.0 4.0 tape format: 0 => 3. 1 for 16-bit integer 2 for 32-bit integer 3 for 32-bit IEEE floating point 4 for 8-bit integer BLOCKING 0.0 10.0 tape blocking factor (<= 10) QUANTIZE 0.0 Quantize images written ***** BE CAREFUL!!! DOUVCOMP -1.0 1.0 > 0 => write compressed form of uv data in output tables NPIECE 0.0 90.0 Break uv data into NPIECE pieces BDROP 0.0 90.0 Don't write the first BDROP pieces CATNO Limit range of DOALL ---------------------------------------------------------------- FITAB Type: Task Use: FITAB converts the standard header and map or uv data and writes it on an output tape in the FITS format. The first or all uv or image files that match the input parameters can be written. The tape is left following the End-of-file mark which terminates the last file written. All Clean Components extension files for maps or ANtenna files for uv data will be written with the image in a standard binary TABLES format (following the image or itself in the file). Other tables-format extension files will also be written. FITAB differs from FITTP in that it writes uv data as a binary table rather than a "random-groups" structure. This allows it to be written in a compressed format that is essentially the same as compressed uv data on disk. It also allows the data if it is in time order to be written as multiple files each covering no more than a specified time interval. ***************************************************************** FITAB IS NEW IN 15APR99 AND ITS UV-DATA OUTPUT CANNOT BE READ IN TO EARLIER VERSIONS OF AIPS ***************************************************************** Adverbs: DOALL......True (> 0) means do all files matching the input parameters, false (<= 0) means do the 1st match only. INNAME.....The input image name (name). Standard defaults. INCLASS....The input image name (class). Standard defaults. INSEQ......The input image name (seq. #). 0 => any if DOALL is true, 0 => highest if DOALL is false. INDISK.....The input disk unit #. 0=> search all disks in order for file meeting the other criteria. INTYPE.....The input data type (MA or UV or ' ' for either) OUTTAPE....The output tape unit #. 0=> 1. DATAOUT....The name of a disk file into which to write. If blank then write to tape. If output is to a disk file, only 1 file can be written (DOALL=-1). If the data set is broken into multiple pieces, then the file name will have a character appended to it representing the piece number. The name is limited to 48-characters and must be in the form : or ::: where is the remote computer name, is the environment variable (logical name) for the disk area in which the file named is to be stored. is usually omitted when the file is local to the current computer. DOEOT......True (> 0) means to advance the tape to the end of information (double EOF) before writing, false means write wherever the tape is now positioned. Note: set DOEOT true ONLY if you think that there are already FITS data files on the tape AND if you wish to preserve them. FORMAT.....Code to tell what format to be used in writing the main image data portion of the file as 1 for 16-bit integers - only images 2 for 32-bit integers - only images 3 for 32-bit IEEE floating point - images 4 for 8-bit integers - only images Default: 0 => 3. If you want to import your FITS data into another system, make sure that it is able to read the format that you have selected. Tables including all UV data are written in a format appropriate to their columns. The UV visibilities are in a format controlled by DOUVCOMP. BLOCKING...Code to tell what blocking factor to be used in writing the whole file Default: 0 => 10. Considerations: (a) blocking factor <= 10. (b) Blocking is ignored when writing to disk rather than tape. (c) Larger blocks use fewer I/O operations making tape reads and writes more efficient. QUANTIZE...<= 0 => write the output image with the maximum possible accuracy (as is done by FITTP). > 0 => quantize the output image so that the least bit has the value QUANTIZE in the units of the image. This parameter is ignored for uv data. If FORMAT is 1 or 2, the task will use format 2 for output if necessary to avoid clipping the image values. If FORMAT=3, the task will integerize the image values with QUANTIZE and then write the image in IEEE floating point. This option is usefull when the FITS file is to be compressed (with gzip for example) for more efficient storage or transmission. If QUANTIZE < 1/4 of the noise in the image, then the noise in the output image will be only a percent or 2 larger than in the input. This is a very dangerous option; if QUANTIZE is set too high the image is severely compromised. ************** BE CAREFUL. **************** DOUVCOMP...> 0 => write the uv data out in a compressed format similar to the compressed format used on disk. This can reduce the size of the files by as much as a factor of 3, but limits the dynamic range within a single visibility sample to a part in 32700 or so. It also means that a single weight is assigned to all unflagged samples in the record. This may be undesirable in the presence of averaging of data that are flagged differently for different Stokes, IFs, and/or spectral channels. <= 0 => write the samples in 3 floating-point values (real, imaginary, weight) per channel/IF/Stokes. NPIECE.....The UV data may be broken into NPIECE segments. Writing several smaller files may be more reliable on magnetic tape or across networks. If pseudo-tape disk files are being written, the output files for the additional pieces will have 1 or 2 appended characters in their names giving the sequence numbers. BDROP......If NPIECE > 1 and NPIECE > BDROP > 0, do not write the first BDROP pieces. This option is used for those times in which the first BDROP pieces were written to tape correctly, but the BDROP+1 piece failed for some reason such as running off the end of the tape. CATNO......Range of catalog numbers over which the operation is to take place. CATNO(1) <= 0 -> 1; CATNO(2) < CATNO(1) -> very large. ----------------------------------------------------------------