skygeometry.py 文件源码

def length(self):

        """
        This function ...
        :return:
        """

        dec_start = self.start.dec.to("deg").value
        dec_end = self.end.dec.to("deg").value

        dec_center = 0.5 * (dec_start + dec_end)

        ra_start = self.start.ra.to("deg").value
        ra_end = self.end.ra.to("deg").value

        # Calculate the actual RA and DEC distance in degrees
        ra_distance = abs(coordinates.ra_distance(dec_center, ra_start, ra_end))
        dec_distance = abs(dec_end - dec_start)

        ra_span = ra_distance * Unit("deg")
        dec_span = dec_distance * Unit("deg")

        return math.sqrt(ra_span**2 + dec_span**2)

    # -----------------------------------------------------------------