LRGB image of MASTER OT J192441.01+620639.4, a transient event listed as a possible supernova. But there is no galaxy nearby. It is possibly a dim star of our own galaxy showing an outburst. The DSS does not show anything at the position of the event, The SDSS DR12 shows a very red and dim object which could be a star but is classified (possibly misclassified?) as a galaxy. In case that it is an outbursting star, then the star must have had a rise in brightness of 10 magnitudes. Also possible would be a giant outburst of a distant and unknown quasar. The event was discovered by MASTER robotic net on 2017-09-10.871 UT at a magnitude of 15.4 and published by ATEL 10370. The source is clearly blue.

Images by M. Mrotzek

Luminance image (left) and the field around the event from the DSS (below) and SDSS DR12 (bottom).



Above: DSS image



Above: SDSS DR12 image. The dim red star is marked by an arrow.