Lake Sonoma 6/17/06

by Steve Gottlieb


We had a nice turnout last night at Lake Sonoma for a short (moonrise about 1:15) but pleasant evening of observing. When I arrived at sunset there was a breeze cooling down the temperature but as it darkened (and the Saturn/Mars pair as well as Mercury emerged) the breeze died down and observing conditions were delightful until moonrise. Seeing was only fair and deteriorated the last hour or so, so viewing was restricted to about 220x in my 18-inch Starmaster. Some of the folks enjoying the evening were Mike Portuesi, Linda and Norm Mahan, Bob Douglas and Matt Marcus (I'm sure he'll also post a report).

Although we're nearly at the summer solstice and the spring constellations are sliding down in the western sky, I took a look at a few of the spring favorites that came up in the recent thread on TAC. For more observing notes on these objects and 6500 additional NGC's, see http://www.ngcic.org/gottlieb/default.htm Steve Gottlieb

Hickson 61 (NGC 4169/4173/4174/4175

NGC 4169 is the brightest member of HCG 61 = "The Box". Appears moderately bright, fairly small, elongated 3:2 NNW-SSE, 1.2'x0.7'. Well concentrated with a 25" bright core that increases to the center. NGC 4174 is the smallest member of the striking HCG 61 quartet. It appeared fairly faint, fairly small, elongated 3:1 SW- NE, 0.9'x0.3', sharply concentrated with a bright 15"-20" rounder core with the extentions much fainter. NGC 4173 is the faintest member of the quartet. At 220x it appeared fairly large, very elongated 4:1 NW-SE, 1.5'x0.4'. Overall, low surface brightness with a very weak central brightening. NGC 4175 is the second of two edge- ons in the group. It appeared fairly faint, moderately large, elongated 5:1 NW-SE, 1.3'x0.25', broad weak concentration to a slightly brighter bulging core and fades at the tips.

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NGC 4216
12 15 54.2 +13 08 59
V = 10.0; Size 8.1x1.8; Surf Br = 12.8; PA = 19d

18" (6/17/06): very bright, very large, extremely thin edge-on 8:1 SSW-NNE, 7'x0.9'. Sharply concentrated with a striking high surface brightness core ~0.9'x0.3' that dominates the extensions with a mag 14 star just following the core. A dust lane appears to run along the eastern edge of the galaxy, mostly evident by a sharp light cut off along this edge. Brightest of three edge-ons in the field with N4206 and N4222.

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NGC 5474
14 05 01.2 +53 39 44
V = 10.8; Size 4.8x4.3; Surf Br = 13.9

18" (6/17/06): fairly bright, large, with an irregular asymmetric appearance. Broadly concentrated to a 1' brighter core that resides on the north edge of the galaxy. The 2.5' halo is slightly elongated N-S and spreads out from the core only towards the south! The halo has a slightly mottled texture and fades at the periphery. With averted vision the size increases to nearly 3'. A mag 13.5-14 star is just north of the offset core. A mag 13 pair at 14" lies 9' ESE. This disturbed galaxy is a member of the M101 group and the asymmetry is caused by tidal deformation by M101!

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NGC 5746
14 44 55.8 +01 57 19
V = 10.3; Size 7.4x1.3; Surf Br = 12.6; PA = 170d

18" (6/17/06): superb edge-on 7:1 N-S, ~6'x0.8', broadly concentrated to a 2'x0.7' elongated, bulging core. The core is mottled and clumpy due to a dust lane that appears to pass along the east edge of the core. The southern extension passes through a star and is slightly brighter and possibly longer though the northern extension extends as far with careful viewing (slightly lower surface brightness).

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NGC 5907
15 15 53.3 +56 19 44
V = 10.3; Size 12.6x1.4; Surf Br = 13.3; PA = 155d

18" (6/17/06): extremely large edge-on, roughly 12:1 NNW-SSE, ~10'x0.8', broadly concentrated to a brighter core but with no discernable nucleus. The 2' central core region is mottled with a couple of brighter spots and the extensions are also irregular in surface brightness. There appears to be a dust lane running along the western edge of the galaxy. A mag 14 star is just preceding the core.

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NGC 5981
15 37 53.3 +59 23 29
V = 13.0; Size 2.8x0.5; Surf Br = 13.1; PA = 140d

18" (6/17/06): fairly faint, fairly large thin edge-on 5:1 NW-SE, 1.5'x0.3'. Broad weak concentration though no well-defined core. First of a striking trio with N5982 and N5985.

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NGC 5982
15 38 39.8 +59 21 21
V = 11.1; Size 2.6x1.9; Surf Br = 12.9; PA = 110d

18" (6/17/06): fairly bright, moderately large, slightly elongated, sharply concentrated with a high surface brightness core increasing to a stellar nucleus. The halo is much fainter and increases in size to ~1.5'x1.2'. Second of an excellent trio in a string with N5981 and N5985.

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NGC 5985
15 39 37.0 +59 19 55
V = 11.1; Size 5.5x3.0; Surf Br = 14.0; PA = 13d

18" (6/17/06): fairly bright, large, elongated 3:2 ~N-S, the halo extends to ~4'x2.5'. Broadly concentrated to a brighter 40" core that increases slightly to the center. The halo is mottled and patchy giving a strong impression of spiral structure. This is largest and brightest overall of an excellent trio with N5981 and N5982.

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