def project(self, object_radec):
        az, alt = radec_to_azalt(self.date, object_radec, self.reference_lonlat)

        if self.azalt_offsets:
            daz, dalt = self.azalt_offsets
            az, alt = rotate_azalt(az, alt, daz, dalt)

        return AzAlt(az, alt)
    def unproject(self, azalt):
        if self.azalt_offsets:
            az, alt = azalt
            daz, dalt = self.azalt_offsets
            az, alt = rotate_azalt(az, alt, daz, dalt, True)
            azalt = AzAlt(az, alt)

        ra, dec = azalt_to_radec(self.date, azalt, self.reference_lonlat)

        return RaDec(ra, dec)