A short evening at Lake Sonoma (3/2/02)

by Steve Gottlieb

A small group including David Silva and Robert Leyland met at Lake Sonoma (Lone Rock Flat) for three hours of poking around in the winter and early spring skies. Conditions were quite pleasant -- the gusts that really kicked up in the afternoon in the east bay hills were nonexistent and we were treated to calm, dry conditions. Seeing and transparency were both good, although for much of the evening I was just loafing around at low power (NGC 2452 at 380x was an acception), revisiting old friends and enjoying bright eye candy. By 10:30 or so, the moon was starting to rise and we started packing up.

NGC 1435 = Merope Nebula = Ced 19j	03 46 10 +23 45.9	Size 30x30
17.5": at 100x, the Merope Nebula is the brightest of the reflection nebulae that encase the Pleiades. It appears as a moderately bright, very large, fan-shaped cone of light extended in a wedge SW to SE from Merope. The boundary of the nebulosity is straighter and better defined along the SE edge where it follows a string of mag 10-11 stars. The SW border is not as well defined but extends beyond a a trio of mag 13 stars. The fan is broadest at its southern extremity which is roughly 15' from Merope.
NGC 1491 = LBN 704 = Sh 2-206	04 03 13.6 +51 18 58	Size 3x3
17.5": at 100x, this is a moderately bright, roundish glow,~3' diameter, mostly west of a mag 11 star. Excellent contrast gain with an OIII filter as it appears bright, with an irregular surface brightness and it wraps around the mag 11 star, particularly on the north side. There is a subtle bite cut out of the nebulosity from the east side that creates a darker hollow extending just west of the star. At 220x (unfiltered), about a half dozen stars are involved or at the edges. The nebulosity is quite irregular with a high surface brightnesss region preceding the star. Faint, elongated, haze extends from this patch to the NE past the star giving an elongated appearance. A pair of mag 13-14 star are at the northern end and another pair are just off the western edge.
NGC 1579 = LBN 767 = Sh 2-222	04 30 14.3 +35 16 47	Size 12x8
17.5": this bright reflection nebula appears nearly 5' in diameter with a prominent, slightly elongated 1.5' central region. The haze is irregular extending outward from this knot with the borders seemingly marked by a half-dozen stars situated around the periphery including a mag 11 star 2' N, a wide pair of mag 11.5-12 stars 1.6' and 2.3' NE and a pair of mag of mag 13 star ~2.5' S. Nebulosity extends mostly west and southwest of the central mass with a very faint piece to the south.
IC 2162 = Ced 72 = LBN 859 = Sh 2-257 = Sh 2-255	06 13 04 +17 58.7	Size 4
17.5": at 100x without filter, IC 2162 consists of two faint, round glows surrounding mag 10.5-11 stars. The eastern object is Sh 2-255 and is the brighter and larger of the pair, nearly 4' in diameter and quite symmetic. Just under 5' due W is a 3' dim glow (this is Sh 2-257). The pair of HII knots are situated midway between two mag 6 stars with a 50' separation near the edge of the 20 Nagler field.
Ced 90 = Gum 3 = Sh 2-297 = vdB 94 = HD 53623 = LBN 1039	07 05 16.7 -12 19 35	Size 10x10
17.5": at 64x appears as a faint, round, 3' haze surrounding a mag 8.5 star. Two mag 10.5 stars are collinear off the east side, 2.5' and 3.3' from the center and several mag 12 stars are involved at the south edge. The H-beta filter noticeably improves the contrast and makes the nebulosity an moderately bright, direct-vision object. With averted vision the glow increases to 4'-5' in diameter with some very faint haze extending east. The star density drops off immediately to the west, except for a few stars. Ced 90 is located at the extreme southern tip of the 2.5 degree giant emission nebula IC 2177 which extends north into Monoceros. This is one of a select group of low-excitation nebulae that can be added to the list of H-beta objects.
NGC 2362 = E492-SC9	07 18 42 -24 57.3	V = 4.1; Size 8
17.5": at 100x, this is a gorgeous, uniformly rich cluster surrounding Tau CMa, which is offset north of center. A WNW-ESE string of stars north of Tau gives a flattened border and the rich southern portion tapers to the south giving a triangular appearance. At 220x, ~60 stars are visible in a 6' diameter, many of 10.5-11. Just following the central star to the ESE are two mag 11 companions. Several other fainter stars are in the central core including on fairly close preceding.
NGC 2438 = PK 231+4.2 = PN G231.8+04.1	07 41 50.6 -14 44 07	V = 11.5; Size 73"x68"
17.5": at 280x this is a beautiful, 1' diameter PN with a darker central hole at 280x situated on the NE side of the rich oc M46. A mag 13 star (not the central star) is within the central hole slightly offset NW of center. The rim is fairly uniform but slightly brighter along the NE side. The central hole is clearly darker although there is not a dramatic contrast. About 15"-20" SW of the mag 11 star a faint mag 14-15 star was intermittently visible. A brighter mag 11 star is just off the SE edge and a string of faint stars oriented WNW-ESE is just over 1' S.
NGC 2452 = PK 243-1.1 = E493-PN11 = PN G243.3-01.0	07 47 26.2 -27 20 08	V = 11.9; Size 31"x24"
17.5": at 380x this is a moderately bright, fairly small but interesting planetary. Appears elongated N-S, ~30"x20" with an irregular surface brightness and a slightly darker center or a darker spot. The halo appears brighter at the north and south ends giving a slightly bipolar appearance with the impression of two lobes diminishing in brightness in the center. A faint mag 14.5 star is just off the north edge. Located 8' S of open cluster N2453.
NGC 2453 = Cr 162 = E493-SC012	07 47 34 -27 11.7	V = 8.3; Size 5
17.5": at 220x, this is a small but dense open cluster with about two dozen stars resolved in a 3' region with a mag 9.5 star (SAO 174539) at the NW edge. A very rich 1' clump of mag 12-13 stars is on the SE side with a mag 11.5 star at the south tip of this clump. Two mag 11 stars are 2' S and 2' SE of the central group. Planetary nebula N2452 is in the field 8' SSW making for an interesting pair.
NGC 2467 = E493-SC25 = Sh 2-311 = LBN 1065	07 52 29 -26 25.8	Size 8x7
17.5": Using a 31 Nagler at 64x and an OIII filter, this is a prominent 7' nebulosity surrounding a mag 8 star. A dark lane appears to cut through the nebula from west to east starting NW of the central star. Fainter nebulosity extends beyond the dark lane but then fades out to the north. The south and southeast border of the main mass has a bright, distinct edge and the southern border has a small extension on the west edge which hooks towards the NW. A finger of nebulosity extends from the main body towards the NW and involves a scattered group of brighter stars (this is Haffner 18). This strip dims but nearly merges with a much larger, elongated mass of fairly faint nebulosity extending NW to SE at a roughly right angle. This section is ~15' in size with an irregular border that is bounded on the NE side by a string of brighter stars. This is a fascinating HII complex to explore in a rich star field!
Jones-Emberson 1 = PK 164+31.1 = PN G164.8+31.1	07 57 52.6 +53 25 18	V = 12.0; Size 405"x360"
17.5" (3/2/02): excellent view at 64x (31 Nagler) and OIII filter. Appears fairly faint but clearly quite irregular in surface brightness and with a nearly 6' circular boundary. The center is darker giving an annular appearance and brighter arcs are along the NW and SE borders with the large SE knot slightly brighter.