Off the Beaten Path with Steve Gottlieb:
Summer Deep Sky Challenges
NGC 6166 = ARC 2199
16 28 38.4 +39 33 05
This is a giant "cD" galaxy at the center of the rich cluster Abell 2199. By itself, this galaxy is unremarkable visually - I recorded it as "fairly faint and small, elongated 4:3
SW-NE, broad concentration." What is remarkable is the surrounding halo of extremely faint galaxies. Within a 5' circle I viewed 6 extremely small and faint companions swarming like bees
around NGC 6166!! How many of these dim companions can you view? N6166A 2.3' SW, N6166B 2.9' E, N6166C 3.1' NW, N6166D 2.0' S, MCG +7-34-64 4.8' SSE and an anonymous galaxy just off the
south edge of N6166.
Djorgovski 2 = E456-SC38
18 01 49 -27 49.6
Discovered photographically on the European Southern Observatory (ESO) Sky Survey, E456-SC38 was reclassified as a globular by Djorgovski in 1987.based on a CMD (color-magnitude diagram.
What's particularly interesting is the location - just 21' WNW of NGC 6520/B86! (one of the most prominent dark nebulae in the sky). At 140x, E456-SC38 showed up as a faint, oval glow
~1.5'x1.1' with no hint of resolution other than one or two faint stars glimpsed at the edges. At 220-280x, it appeared oriented SW-NE and stands out well with averted vision with a fairly
sharp outline but appeared more like a faint patch of nebulosity than a globular. A few mag 15+ field stars were visible at the edges - the easiest at the SW end and a second star at the NE
edge. One of two other threshold stars are superimposed.
The rich milky way background is quite prominent in the field except in the vicinity of the globular which appears nestled in a darker "hole" defined by four brighter stars. The globular
is sandwiched within a small trapezoid defined by a mag 9 star to the south, a close double star 2.5' NNW and two mag 10 stars bracket the cluster on the west and east sides.
This huge planetary has listed dimensions of 475"x330"! Nothing was visible unfiltered, but using an OIII filter at 100x, Sh 2-68 appeared as a very large, round, low surface
brightness glow, perhaps 5'-6' in diameter. It required averted vision but the halo had a fairly crisp edge and surface brightness was uniform. This is a recent 1983 discovery and is
possibly a HII region.
Sharpless 2-71 = PK 36-1.1
19 01 59.3 +02 09 18
This object is an unusually prominent obscure planetary and was !immediately picked up at 100x using an OIII filter Probably the best view was filtered at 140x and it was seen as a
fairly large glow, elongated N-S and brightest along the east side. I had the impression it was mottled with a noticeably irregular surface brightness. You will find this nebula 6'
following a mag 10 star and several mag 11-12 stars are nearby.
Arp 2
19 28 44.1 -30 21 14
Arp 2 is one of four globulars (along with Terzan 7, 8 and M54) that may be associated with the recently discovered nearby Sagittarius Dwarf Spheroidal Galaxy (Sgr dSph ) which was
discovered in 1994. This might explain an apparent anomaly - it appears roughly 3 billion years younger than typical metal-poor Milky Way globulars.
Not much is visible in my 17.5-inch: Arp 2 appeared as an extremely low surface brightness glow with a very small brighter core, perhaps 2' diameter, situated in a rich star field. At
moments, a faint star or knot was visible at the center. A distinctive 1.5' clump of five faint stars 5.5' NNE provides a good reference to center the globular.
Parsamyan 21
19 29 00.8 +09 38 45
This object is classified as a cometary nebula - apparently a bipolar reflection nebula with a single visible "tail". At 280x I picked up a faint, round, 15" knot, roughly mag
13.5. It appeared brighter in the center but no clear central star was visible. This nebulosity is situated on a line between a mag 8.2 star 5' ENE and a mag 11.5 star 4' WSW. I didn't pick
up any sign of the "tail" visible on images - let us know if you can pick it up!
This spectacular Hickson Compact Group was voted as a favorite HST image in a public web poll! The Hubble telescope reveals the brightest member (ESO 597-G36) is an edge-on with a
prominent dust lane. With my 17.5-inch, though, it was pretty faint, fairly small, elongated SW-NE, 0.9'x0.3', with a very low even surface brightness. A mag 14/15 double star at 13"
separation lies 1' NW. A close companion (HCG 87B) is collinear with the major axis close off the SW end. Can anyone make out the dust lane visible on the HST image?
The "Elephant's Trunk" is an unusual cometary globule (associated with star formation) on the west side of the huge but faint HII complex, IC 1396. This is a tough object and requires
transparent skies and lots of patience! The most contrasty view was at 100x using a UHC filter, where a 15'x5' lane was evident oriented WSW-ENE, particularly by gently rocking my scope
back and forth. The "tail" of the globule or elephant's "trunk" heads west and is weakly illuminated on the edges, particularly on the south side. Near the "head" is a mag 9 star (SAO
33573) and a pretty double star to the west was embedded in the lane. With careful viewing the "trunk" shows variations in width and opacity.
