I'm not sure if this topic is covered elsewhere, though I feel it probably must be since it is something I have questions about rather frequently. My question is: How can you tell when the target might be a distant galaxy behind the larger host galaxy? As such, I wouldn't think classification of the host is what they're looking for.
Other cases include ones where forground stars are pinpointed as the targets inside a larger host galaxy, so when you see these, you might assume it's targeting a part of the galaxy and classify it rather than noticing it's actaully a STAR.
the one below is one that falls in this categoryhttp://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587741709406896132
If you click on the link it shows in SDSS that the targeted object is a STAR, so shouldn't it be classified as S/DK??
.....and if the target specClass is "GALAXY", how can you be sure that it isn't gating on a distant galaxy behind (or maybe even in front of) the larger one?
Any clarrification would be greatly appreciated........and, if this has already been addressed elsewhere, please forgive me.