NGC 2261 – Hubble’s Variable Nebula
NGC 2261 is a bright diffuse nebula in the constellation Monoceros. It was discovered by William Herschel in 1783. It became quite famous in the early 20th century as Edwin Hubble and others observed the object showing very different appearances in different photographs. It is now theorized these variations are changes in the shadows cast by dust clouds around the embedded star R Monocerotis. The nebula was also the subject of the very first image taken by the 200-inch telescope at Palomar Observatory in 1949.
Somehow in all my years of observing, I had not managed to get a look at NGC 2261 until just this Sunday, and I wish I had done so sooner. It is a lovely object, definitely worth coming back to. It is around 2 arcminutes across in size, so it is large enough to be noticed easily at low power, but small enough to want to use high power to examine it in detail. I made my observation with my trusty 16”, but don’t worry; it is bright enough that it should be easily visible from our Dark Site in considerably smaller telescopes. My log entry is as follows:
Transparency very good
16” f/4.5 reflector at 131x
Cone-shaped or fan-shaped nebula; tip points to the south and is starlike; surprisingly bright; seems slightly brighter on the edges of the fan than in the center; this effect is exaggerated when an OIII filter is used, though the overall response to the filter is not very good
The HAS VSIG would love to hear about your own visual observations of NGC 2261. Send them to me at [email protected] or just share them to the VSIG list server (contact me to subscribe to that list also).