On the right side, one can find the galaxy UGC 378(see the object ID). There is a blue-greenish objectin the foreground of Ugc 378, or maby it is an object inside that galaxy. If it is in Ugc 378, it might be a very bright supercluster, consisting of young blue stars. If the object is in the foreground, it might be an planetary nebula. I made a comparison of the RGB-channels and a OIII-filtered image, one can find it here. As one can see, the object is visible in RGB and, very faint, also in OIII.