projector.py 文件源码

def celToGal(ra, dec):
    """
    Converts Celestial J2000 (deg) to Calactic (deg) coordinates
    """
    dec = numpy.radians(dec)
    sin_dec = numpy.sin(dec)
    cos_dec = numpy.cos(dec)

    ra = numpy.radians(ra)    
    ra_gp = numpy.radians(192.85948)
    de_gp = numpy.radians(27.12825)

    sin_ra_gp = numpy.sin(ra - ra_gp)
    cos_ra_gp = numpy.cos(ra - ra_gp)

    lcp = numpy.radians(122.932)    
    sin_b = (numpy.sin(de_gp) * sin_dec) \
            + (numpy.cos(de_gp) * cos_dec * cos_ra_gp)
    lcpml = numpy.arctan2(cos_dec * sin_ra_gp,
                          (numpy.cos(de_gp) * sin_dec) \
                          - (numpy.sin(de_gp) * cos_dec * cos_ra_gp))
    bb = numpy.arcsin(sin_b)
    ll = (lcp - lcpml + (2. * numpy.pi)) % (2. * numpy.pi)
    return numpy.degrees(ll), numpy.degrees(bb)