snorer.equatorial_to_beta¶

snorer.equatorial_to_beta(ra,dec,GC_coord=None)¶

Transform equatorial coordinate to off-center angle and galactic coordinate \((\beta,\ell,b)\).

Parameters:

ra : array_like
    Right ascension, hms in string type. Eg. '5h6.7m4.4s'.

dec : array_like
    Declination, dms in string type. Eg. '6d10.7m9.4s'.

GC_coord : None/list
    The equatorial coordinate for arbitrary galactic center. Default is None, which automatically implements our Milky Way center. For a specific GC coordinate, it should have GC_coord = [RA,DEC] where RA and DEC are, similar to ra and dec, in hms and dms units respectively. Additionally, they should be subject to ICRS J2000.0.

Returns:

out : tuple
Tuple of \((\beta,\ell,b)\) in rad. Each component is scalar if all inputs are scalars.

Notes

We rely on astropy.coordinates.SkyCoord in Astropy to resolve \((\ell,b)\) from \((\alpha,\delta)\) and obtain \(\beta\) by snorer.galactic_to_beta.