euler: Transform between Galactic, celestial, and ecliptic...

In astrolibR: Astronomy Users Library

Description

Transform between Galactic, celestial, and ecliptic coordinates

Usage

euler(ai, bi, select, fk4, radian)

Arguments

ai	longitude, in degrees unless radian=TRUE is set, scalar or vector
bi	latitude, degrees unless radian=TRUE is set, scalar or vector
select	integer (1-6) specifying type of coordinate transformation: 1 = RA-Dec (J2000) to Galactic; 2 = Galactic to RA-Dec; 3 = RA-Dec (J2000) to Ecliptic; 4 = Ecliptic to RA-Dec; 5 = Ecliptic to Galactic; 6 = Galactic to Ecliptic
fk4	set to TRUE if input and output celestial and equatorial coordinates are given in equinox B1950 (default = FALSE)
radian	set to TRUE in all input and output angles are in radians rather than degrees (default = FALSE)

Details

J2000 coordinate conversions are based on sec. 1.2 of Perryman (1997).

Related functions are provided in CRAN packages moonsun and sphereplot.

Value

ao	longitude, in degrees
bo	latitude, in degrees

Author(s)

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

R adaptation by Arnab Chakraborty (June 2013)

References

Perryman, M. (editor) 1997, The Hipparcos and Tycho Catalogues, Vol. 1, ESA SP-1200. http://www.rssd.esa.int/SA/HIPPARCOS/docs/vol1_all.pdf

Examples

# Input: RA and dec of Cyg X-1
# Output: Galactic long and lat  = (71.334990, 3.0668335)

euler(299.590315, 35.201604, 1) 

Example output

Called from: euler(299.590315, 35.201604, 1)
debug: return(list(ao = ao, bo = bo))
$ao
[1] 71.33499

$bo
[1] 3.066834

astrolibR documentation built on May 2, 2019, 3:26 a.m.