; CELGAL ;--------------------------------------------------------------- ;! switches header between celestial and galactic coordinates ;# Verb Catalog ;----------------------------------------------------------------------- ;; Copyright (C) 1995, 2009 ;; 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 ;----------------------------------------------------------------------- CELGAL LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC CELGAL: Verb to switch between Celestial and Galactic coords INNAME Image name(name). INCLASS Image name(class). INSEQ 0.0 9999.0 Image name(seq. #). 0=>high INDISK 0.0 9.0 Disk drive #. 0=>any ---------------------------------------------------------------- CELGAL Type: Verb Use: CELGAL switches the axis descriptions between Celestial and Galactic coordinates. The verb works for images projected simply to the tangent plane. These projections are indicated in the image header by the strings '-SIN', '-TAN', and '-ARC' which describe the kind of projection (VLA, standard optical, and Schmidt or equal-angle, respectively). Adverbs: INNAME......Image name(name). Standard defaults. INCLASS.....Image name(class). Standard defaults. INSEQ.......Image name(seq. #). 0 => highest. INDISK......Disk drive # of image. 0 => any. ---------------------------------------------------------------- CELGAL: Verb to transform the coordinate system between Ra and Dec and the Galactic coordinate system. The coordinate transformation is implimented as a simple rotation between the two coordinate systems as a function of three parameters. The three parameters are the coordinate of the north galactic pole in (1) RA and (2) Dec and (3) galactic latitude of the North celestial pole. These three parameters are a function of the epoch of observation (ie B1950 or J2000). If the epoch of observation is not 1950, the coordinate transformation for J2000 is used. For coordinate parameters are tabulated below: N. Galactic Pole N. Celestial Pole Epoch Ra Dec latitude (degrees) (degrees) (degrees) ----- --------- --------- --------- 1950 192.25 24.4 123.0 2000 182.859375 27.128653 123.932018 ----------------------------------------------------------------