Brief observing report w/17.5", Digger Pines 2/14

by Steve Gottlieb

Probably like most people I had given up hope on observing this weekend but while I was walking the dog around 3:30 yesterday afternoon I was very surprised to see the sky clearing with lots of blue sky to the east, so I rushed home, literally threw my observing gear in the minivan and headed off for Digger Pines (Tri-Valley club site on Mines Road near San Antonio Valley) about 4:15. When I arrived at 6:00 the sky was perfectly clear, no wind but there seemed to be quite a bit of moisture still in the air from the passing front. Soon afterwards a couple of club members drove up and we all set-up in darkening twilight.

It soon became clear that although the transparency was fairly dark, seeing was soft, dew was going to be a problem and the moisture was reflecting quite a bit of skyglow from San Jose and Morgan Hill to the west and southwest. So, I knew I had to stay near the meridian or further east for optimal viewing. I ended up observing about three hours until it was obvious my secondary was dewed up (not to mention the Telrad and finder). Among the observations, I did get fairly detailed views of a few brighter bi-polar planetaries with a 5.2 Pentax XL and a glimpse of a giant, ancient PN (Abell 31 in Cancer).

NGC 2440

This bi-polar planetary reveals fascinating detail at 380x! The compact high surface brightness inner region is elongated NNW-SSE. Two bright knots comprise both ends and the surface brightness is irregular. The nebulosity is much weaker soutwest of the main body with a cup-shaped dark "notch" protruding into this central bar. The outer halo is oriented SW-NE with a brighter wing similar to a spiral arm which is attached at the west edge and curving back towards the south. The outer nebulosity is weaker and less well-defined on the north and northeast sides.

NGC 2371/72

Very unusual appearance at 380x with two bright knots oriented SW-NE about 30" between centers. The SW knot is 15"-20" in size, slightly elongated and the brighter of the two. The NE condensation has a slightly lower surface brightness and appears ~20" in diameter. Symmetrically placed between the knots is a faint 14th magnitude central star. Weaker nebulosity connects the two knots giving a dogbone appearance and a faint rounder halo encases the structure.

Abell 31

At 100x + OIII filter, a faint, huge, roundish glow encompassing a mag 10 star which is SE of center. With averted vision appears ~8' in diameter, although the edge of the halo is not crisply defined. Not visible without filtration. The bright star is part of a distinctive parallelogram with sides roughly 9'. The PN does not reach the mag 10 star 8' W although on photographs it extends this far. Three very faint galaxies (IC 523, MCG +02-23-8, CGCG 61-20) were also viewed within 30' at 280x.