NGC 1931 (Sharpless 2-237) -- Reflection Nebula & Open Cluster in Auriga
About a degree west of the magnificent open cluster M36 in Auriga, is a small reflection
nebula Sharpless 2-237. Embedded in the reflection nebula is a cluster of stars. Both the
nebula and the cluster are better known as NGC 1931 and referred to as the fly. The
reference refers to “The Spider and the Fly”. The Spider being the emission nebula (IC 417)
and cluster (Stock 8) located about half-a-degree to the northeast of the Fly.
Reflection nebulae are almost always difficult to find from the suburbs since they are subtle
and often remain hidden under light-polluted skies. Also, nebula filters do not work on
reflection nebulae and therefore making detection even harder. NGC 1931 is an exception.
Yes, it is small but even with a low power eyepiece, the nebula is detectable from my
backyard with the 6-inch refractor. The nebula takes magnification well and glows distinctly
in the eyepiece at 182x.