(Left) PARSEC stellar isochrones for 1.3, 2.2, 4.0, 7.1, and 12.6 Gyr with a fixed metallicity of −0.5. The source is most likely an old bright giant or supergiant. (Right) Source distance distribution based on PARSEC isochrones and the extinction estimated from the spectral modelling. Black dashed and dotted lines indicate the median distance value and the 1σ confident region, respectively.