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EULER

EULER

## Purpose

Transform between Galactic, celestial, and ecliptic coordinates.

## Explanation

Use the procedure ASTRO to use this routine interactively

## Calling Sequence

EULER, AI, BI, AO, BO, [ SELECT, /FK4, /RADIAN, SELECT = ]

## Inputs

AI - Input Longitude, scalar or vector. In DEGREES unless /RADIAN
is set. If only two parameters are supplied, then AI and BI
will be modified to contain the output longitude and latitude.
BI - Input Latitude in DEGREES

## Optional Input

SELECT - Integer (1-6) specifying type of coordinate transformation.
SELECT From To | SELECT From To
1 RA-Dec (2000) Galactic | 4 Ecliptic RA-Dec
2 Galactic RA-DEC | 5 Ecliptic Galactic
3 RA-Dec Ecliptic | 6 Galactic Ecliptic
If not supplied as a parameter or keyword, then EULER will prompt for
the value of SELECT
Celestial coordinates (RA, Dec) should be given in equinox J2000
unless the /FK4 keyword is set.

## Outputs

AO - Output Longitude in DEGREES, always double precision
BO - Output Latitude in DEGREES, always double precision

## Optional Input Keyword

/FK4 - If this keyword is set and non-zero, then input and output
celestial and ecliptic coordinates should be given in equinox
B1950.
/RADIAN - if set, then all input and output angles are in radians rather
than degrees.
SELECT - The coordinate conversion integer (1-6) may alternatively be
specified as a keyword

## Example

Find the Galactic coordinates of Cyg X-1 (ra=299.590315, dec=35.201604)
IDL> ra = 299.590315d
IDL> dec = 35.201604d
IDL> euler,ra,dec,glong,glat,1 & print,glong,glat
71.334990, 3.0668335

## Revision History

Written W. Landsman, February 1987
Adapted from Fortran by Daryl Yentis NRL