Observing from Lake Sonoma 2/9/02

by Steve Gottlieb

Here are a sampling of observations made last Saturday night (9 Feb) from Lake Sonoma with my 17.5-inch scope on a homemade platform (by Ray Cash). Transparency was average for this site (close to mag 6.5) and seeing fairly steady up to 280x.

The first two objects below are large, easy reflection nebulae in Perseus and Orion and should be no problem in small scopes.

NGC 1333 = Ced 16 = LBN 741	03 29 19.7 +31 24 57	Size 9x7
17.5": bright, interesting reflection nebula at 140x. Apparently illuminated by a mag 10 star oddly offset at the NE end of the glow. The appearance is irregular; extending ~10'x6' SW-NE in the general direction of a mag 10 star 11' SW. The SW extension contains a couple of faint mag 14 stars and ends at a small, brighter knot which appears to surround a very faint star or stars. The field is oddly void of faint stars and there is a large starless region to the north (this is dark nebula Barnard 2).
NGC 1788 = LBN 916	05 06 53.2 -03 20 27	Size 8x5
17.5": at 144x this is a bright reflection nebula involving two mag 10 and 11.5 stars. The nebulosity is irregularly bright in a 4'x3' region elongated NW-SE and locally very bright in a knot surrounding the mag 11.5 star near the SE end. Enhanced by a Deep Sky filter at low power. The brighter mag 10 star ~2' NW has a faint companion and is also encased in the glow as well as a couple of other fainter stars. A faint extension fans out to the NE from the mag 11 star and some haze is suspected to the south, increasing the size to ~7' and involving a few additional stars. N1788 is located within a bright trapezoid consisting of three mag 8.5-9 stars and a mag 10 star (sides 9'-13').

I had seen IC 417 previously in a C-8 20 years ago -- so figured it was time to update the observation!

IC 417 = LBN 804 = Sh 2-234	05 28.1 +34 26	Size 13x10
17.5": this large HII region encases the open cluster Stock 8 and is situated ~6' SE of 5th magnitude Phi Aurigae. At 140x, the cluster consists of 40-50 stars including two mag 10 (the brightest is the wide double …707 = 9.7/11.4 at 18") and numerous mag 12-14 stars. With a UHC filter (or OIII filter at 100x), the cluster is encased in a moderately bright glow, ~8'x5'. The nebulosity is brightest in a triangular wedge, tapering towards the south with the two mag 10 stars oriented N-S (2' separation) along the western boundary. The glow is irregularly but has a fairly sharp border along the western edge.

The next two galaxies are mainly of interest for their location -- within five degrees of the celestial pole.

UGC 3993 = MCG +14-04-037 = CGCG 362-046 = NPM1G +85.0021	07 55 44.0 +84 55 35	V = 12.8; Size 1.6x1.2; SB = 13.4; PA = 35d
17.5": fairly faint, very small, round, 20"-25" diameter, weak concentration. A mag 12/14 double at 9" separation lies 1.2' E. IC 469 lies 14' N.
IC 469 = U03994 = MCG +14-04-038	07 55 59.4 +85 09 33	V = 12.6; Size 2.2x1.0; SB = 13.3; PA = 90d
17.5": fairly faint, moderately large, elongated 2:1 E-W, 2.0'x1.0', large brighter middle, broad concentration but no nucleus. Surrounded by three mag 8.5-9.5 stars. Mag 8.5 SAO 1236 just 3.8' N is at the west edge of a scattered group of 10 stars including a close, faint double (mag 14/14 at 10"). Mag 9.2 SAO 1224 lies 4.4' SW and mag 9.5 SAO 1237 is 3.6' S. This galaxy is relatively bright for an IC galaxy. U3993 lies 14' S.

Holmberg II is an odd looking Magellanic-type dwarf in the M81 group, but with a pretty low surface brightness. Save this for a dark night.

Holmberg II = U04305 = MCG +12-08-033 = CGCG 331-034 = Arp 268 = VII Zw 223 = LGG 176-007	08 19 04.0 +70 43 09	V = 10.7; Size 7.9x6.3; SB = 14.8; PA = 15d
17.5": immediately picked up at 140x as a large, very diffuse glow mostly west of a distinctive triple star (mag 11.5-12.5) which situated along on the eastern edge of the galaxy! The low surface glow is elongated ~3:2 N-S, ~4'x2.5', although the edges generally fade into the background so the size was difficult to estimate. It appeared slightly brighter in the vicinity of the triple star. The visibility was surprisingly easy and was quite obvious using averted vision although this object appeared more like a faint galactic nebula than a galaxy. I didn't note any of the HII regions seen on images. Holmberg II is an irregular dwarf in the M81 group.

Abell 30 is certainly one of the more difficult of the 46 Abell planetaries that I've viewed --

Abell 30 = PK 208+33.1 = PN G208.5+33.2	08 46 54.4 +17 52 33	V = 13.0; Size 127"
17.5": After pinpointing the exact location, an extremely faint glow was barely visible using an OIII filter at 100x surrounding a mag 14 star (quite dim with the filter). Appeared round and perhaps 30" diameter. Seemed a bit easier to view in Jim Shield's scope at 140x using the OIII filter. A couple of additional mag 14 stars are just N and SW of the planetary. The central star is collinear with two mag 11.5 stars located 6' and 10' W. This is a highly-evolved, hydrogen-poor planetary.