AIPS NRAO AIPS HELP file for CELGAL in 31DEC18



As of Sat Sep 22 8:36:22 2018


CELGAL: Verb to switch between Celestial and Galactic coords

INPUTS

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

HELP SECTION

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.

EXPLAIN SECTION

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










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