Author Topic: OR 7/22 through 7/25: Lassen National Park (part 4)  (Read 1071 times)

sgottlieb

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OR 7/22 through 7/25: Lassen National Park (part 4)
« on: August 30, 2014, 09:55:47 AM »
For a full report with pictures from Lassen and labeled images of all objects described below, go to

 Adventures in Deep Space

Steve Gottlieb

Friday night (July 25th), was the last of four consecutive clear nights at Lassen. And as a nice conclusion, we had our best conditions on this observing adventure. There was no wind or dew at the Bumpass Hell lot and transparency and seeing were both very good to excellent. Here's the set-up on Bumpass with Mark Wagner and another with the view towards the south. Interacting galaxies and compact galaxy groups were mostly the targets for the night, along with the unusual globular cluster Arp GC2, which may have been captured by the Milky Way from the Sagittarius Dwarf Spheroidal galaxy.


VV 158 = Rose 16
13 56 30 +28 31 24
Size: 5.5'

VV 158 is chain of 4 CGCG galaxies with a total length of 5.5', and oriented WNW to ESE. Using 375x, CGCG 162-031, the westernmost galaxy, appeared fairly faint, fairly small, round, 20" diameter, contains a very small bright nucleus. A mag 14 star is 1.5' NW and a mag 15 star is 1.4' NE. CGCG 162-032, situated 1.5' ESE, appeared very faint to faint, round, 10" diameter. This is the faintest member in the chain and just south of the midpoint between CGCG 162-031 1.5' WNW and CGCG 162-033 1.5' E. CGCG 162-033, the third brightest in the chain, appeared faint, small, round, 15" diameter. CGCG 162-034, another 2.5' SW, appeared fairly faint, fairly small, elongated 2:1 NW-SE, 20"x10", small bright nucleus.


VV 59 = Rose 25 (interacting pair)
15 08 04.9 +34 23 14
Size: 0.7'x0.3'; Mag: V = 15.5, B = 16.3

VV 59 was picked up fairly easily at 260x as an faint elongated glow, but best view at 375x. The brighter component (VV 59a) is at the northeast end and appeared faint, small, irregularly round, 15" diameter. It appeared to taper at the northeast tip and brighten (triangular shape on the DSS).

An extremely faint glow extended 15" southwest, increasing the overall length to roughly 25". With careful viewing, a slightly brighter 6"-8" knot (core of VV 59b) would sometimes "pop" within this glow. The two interacting components of VV 59 were connected and not detached.


UGC 9760
15 12 02.4 +01 41 55
Size: 2.6'x0.2'; Mag: B = 15.2

At 260x, this superthin galaxy appeared extremely faint, fairly small, edge-on 6:1 SW-NE, 0.6'x0.1', very low even surface brightness. A mag 14.5 star is at the northeast end. Although images show the galaxy extends northeast of the star, it appeared as a ghostly splinter extending southwest of the star. Located 2.3' SE of a mag 10/12.5 pair at 25". Member of the NGC 5846 Group.


UZC-CG 254 (Galaxy Trio)
17 14 25 +23 04 18
Size: 2.3'; Mag: V = 14.6/15.3/15.3, B = 15.4/16.3/16.4

This small physical triplet contains two CGCG galaxies and a MAC. At 375x CGCG 140-003 appeared faint to fairly faint, small, round, 18" diameter, very small bright core. CGCG 140-002, 2.4' WNW, appeared very faint, very elongated 3:1 NW-SE, ~27"x9", very low surface brightness. PGC 1681151, 0.8' NE was very faint, very small, round, 9" diameter.


HCG 86
19 51 59.0 -30 48 57
Size: 4' diameter; V = 13.1/13.6/14.8/15.0, B = 14.3/14.8/15.7/15.7

At 375x, all four members of HCG 86 were easily visible (direct vision), with HCG 86A the brightest and largest. It appeared fairly faint to moderately bright, elongated 3:2 SW-NE, roughly 27"x18" with a very small bright core. A mag 15.2 star is off the southwest end, 0.5' from center. HCG 82B lies 1.1' WNW, and appeared fairly faint, round, 20" diameter, very weak concentration. A mag 14.8 star is off the west side, 0.4' from center. HCG 86D, just 1.6' WNW, was faint (though easily visible), small, elongated 2:1 NNW-SSE, ~15"x8". Finally HCG 86C was easily seen as a faint, small, irregularly round glow, ~18x15".


NGC 6907/6908 (Barred Spiral with companion superimposed!)
20 25 06.6 -24 48 33
Size: 3.3'x2.7'; Mag: V = 11.2, B = 11.9

Striking example of a barred spiral with a prominent 1.5'x0.5' central bar oriented directly east-west. The bar contains a bright 30" core, which increases to a quasi-stellar nucleus. A bright arm is attached at the east end of the bar and extends due north for 0.7', at a right angle to the bar. A bright, elongated N-S "knot" is embedded in the middle (superimposed companion NGC 6908). At the north end, the arm curls west a short distance while dimming out. A difficult, ill-defined arm is attached at the west end of the bar. It vaguely curves south and west, but quickly disappears into very low surface brightness haze.


HCG 87
20 48 14.9 -19 50 53
Size: 1.5' total for group; Mag: B = 15.3/15.4/16.1/17.6

Using 260x and 375x, HCG 87A appeared faint to very faint, elongated nearly 3:1 SW-NE, 45"x15", fairly low even surface brightness. A mag 14/14.5 pair at 13" lies 0.7' NW and a mag 12 star is 2.5' NE, collinear with the major axis. HCG 87B is just 1' SW and HCG 87C is 1.3' NW. The former galaxy is faint, round, ~18" diameter, compact with a high surface brightness, while HCG 87C is very faint, elongated 3:2 E-W, 15"x10". Low even surface brightness with no core. HCG 87D is a toughie (mag 17.6B) and I only managed a marginal sighting at 375x with one good "pop" in the correct location. ESO 597-034 lies 7' southwest of the quartet and appeared faint, small, round, 20-25" diameter. .


WBL 673 (Galaxy Group in Pegasus)
21 53 12.0 +15 33 10
Size: 7.8'

Using 375x, CGCG 427-034 appeared fairly faint, round, 0.8' diameter, fairly low surface brightness. Contains a slightly brighter 15" core. First and largest of four with CGCG 427-035 6' NE and CGCG 427-036 6.6' ESE. CGCG 427-035 is very faint, small, elongated 5:2 SW-NE, 20"x8", low surface brightness. Located close NE of a group of 5 stars. CGCG 427-036 is fairly faint, fairly small, round, 20", small brighter core. Slightly fainter than CGCG 427-037 1.7' SE, which appeared fairly faint, fairly small, round, 20" diameter, small bright core.


NGC 5921
15 21 56.5 +05 04 14
Size: 4.9'x4.0'; Mag: V = 10.8, B = 11.5

At 260x, this multi-armed barred spiral appeared bright, fairly large, elongated 3:2 ~N-S, sharply concentrated with a striking, very bright core. Extending SSW to NNE is a slightly brighter bar (fairly low contrast). The very begnning of a spiral arm is evident as an elongated glow at the north end of the bar, extending a very short distance to the northwest. The view was improved at 385x with a strong hint of a second spiral arm beginning at the south end of the bar and starting to bend east. Contains a bright, sharp stellar nucleus. A mag 10 star is 3' SE and a mag 12 star is at the southwest edge.

Arp GC 2
19 28 44.1 -30 21 14
Size: 2.5' diameter; Mag: V = 12.3

Very faint, moderately large, low surface brightness glow, roughly 2' diameter. Contains a small, slightly brighter core or knot near the center. Slightly grainy or mottled appearance, but no clear resolution except around the edges (possibly field stars). Located 5' SW of a distinctive asterism consisting of a 1.5' east-west chain of four stars, with a fifth star 0.4' south of the center of the chain. Located 2.5 degrees WNW of M55.

In 1965 (Galactic Structure, University of Chicago Press, page 401), Arp noted a new "...sparse globular cluster a plate of which was formed in Baade's file..." and reported it as Anonymous. Arp GC 2, along with Terzan 7, Terzan 8 and others lie very close to the Sagittarius Dwarf Spheroidal galaxy (discovered in 1994) and appear to be former members of that galaxy.
« Last Edit: August 30, 2014, 10:08:35 AM by sgottlieb »