Sketching Superbubbles

A GREAT NIGHT STAYS WITH YOU forever, long after ordinary good nights fade away. On the night in question, afternoon clouds earlier in the day had lowered my spirits, but a clearing twilight later raised them. I didn’t need an SQM, or sky quality meter, reading to tell me that sky conditions were sterling: The Milky Way and zodiacal light were intense.

I grabbed my 15-cm f/2.8 telescope with a 4.3° field of view and pointed it at my target: the vast Eridanus Superbubble west of Orion. I warmed up on the Orion Nebula (M42) then pushed over to the Horsehead Nebula to test sky conditions. I could see the) Orionis Ring, Sharpless 2-264. The edge was bright and curved in the wrong direction. Oh, I was seeing the northern reach of Barnard’s Loop and it was obvious! I traced the Loop to the east and found M78 floating brightly in a sea of smoky nebulosity, then continued tracing the Loop as it arced below M42. Transparency was the best it had been in months.