OR 9/11/10: A night with some UC Berkeley luminaries

Known as the Berkeley clusters (or Setteducati-Weaver clusters), these stellar assemblages were discovered around 1960 by UC astronomers Harold Weaver and Arthur Setteducati. They searched the Palomar Observatory Sky Survey (POSS) plates looking for faint, rich open star clusters and found over 80 new objects (some were previously catalogued objects). Generally, these are not impressive visual clusters but there are a few Berkeley standouts. I spent Saturday night at Lake Sonoma, checking out some of the Berkeley luminaries along with a nice crowd at Grey Pine Flat including Ray Cash, Carter Scholz, Dennis Beckley, Caroline Scolari and several others. Conditions were pretty nice -- warm and dry with SQM readings between 21.3-21.4 -- and the friendly crowd made for an enjoyable evening.

Berkeley 2
00 25 15 +60 23.3
Size 4'
At 285x a 20" pair of mag 13 stars are centered on a 2' unresolved background glow. Only two additional mag 14 stars were resolved and a couple of mag 10 stars off the N and SW side of the glow don't appear to be related. Located 8' SE of mag 7.6 HD 1950. NGC 129 lies 35' SE.

Berkeley 51
20 11 54 +34 24.3
Size 4'
At 175x, a mag 12.5 star is surrounded by a faint, hazy glow ~2' in diameter. At 285x, a few faint stars sparkle to the north and south of the brighter star including a short string on the NW end. A total of 8 mag 14-15 stars are resolved over the glow in addition to the brighter star. Located 5' SSW of mag 7.2 HD 192124 and 3' WSW of mag 9.3 HD 228251.

Berkeley 53
20 55 56 +51 04.8
Size 12'
This very faint cluster is situated just west of mag 6.6 HD 199578. At 285x, ~15 faint stars are close NW of the brighter star within a 3' circle. These stars are embedded on the NE side of a larger unresolved background glow. Several mag 10-11 stars are nearby to the north and west of the HD 199578. On the DSS the cluster consists of a cloud of extremely faint stars (not resolved) to the W and SW of HD 199578 and surrounding a couple of mag 10-11 stars. The 15 stars I noted just north may not be cluster members but I probably picked up the unresolved glow of the cluster.

Berkeley 54
21 02 59 +40 26.2
Size 5'
Picked up at 105x as a very faint, hazy patch with no resolution, ~1.5' diamete. Situated just NW of a trio of mag 9/10/11 stars. At 285x a mag 13.5 star and three mag 14-15 star are resolved over the glow, which is elongated SW-NE. Located 1.3° SE of mag 3.9 Nu (58) Cyg. This is one of the oldest open clusters with an age of ~7.2 billion years. See "The age of the oldest open clusters" in 2004, A&A, 414, 163

Berkeley 55
21 16 58 +51 45 32
Size 3'
Picked up at 105x as a hazy glow with a few resolved stars, ~3' diameter. At 285x, roughly a dozen stars mag 13.5-14.5 were resolved mostly in two strings oriented ~E-W. The southern string includes 3 equally spaced stars with the star at the west end a close double. The northern string is longer and includes a half-dozen stars. The cluster is situated at the western vertex of an equilateral triangle with two mag 10 stars ~8' NE and 8' SE.

Berkeley 56
21 17 35 +41 49 36
Size 7'
Picked up at 105x as a faintly glowing spot ~3' diameter with a few brighter stars superimposed. At 285x the glow was still generally unresolved with just a few mag 15 stars resolved. An isosceles triangle of mag 11-12.5 stars is just at the NW edge. A wide pair of mag 12-13 stars is at the south edge. The cluster members were generally too faint (brightest is ~16 mag) to resolve and the glow is unimpressive. Located 28' SSE of mag 6.2 HD 202720 and 26' ESE of mag 6.6 HD 202568. This is an old open cluster with an age of at least 4 billion years.

Berkeley 58
00 00 12 +60 56.5
V = 9.7; Size 5'
Roughly 30 stars mag mag 12-14.5 were resolved in a 6' group with many of the stars in chains. On the NE side is a wide "V" of stars with a mag 9.8 star near the east end of one branch. A Cepheid variable, CG Cas, lies 2' SE of this bright star and is a likely member of the cluster. At the vertex of the V another string extends to the SW and a couple of faint chains of stars branch off from this string.
Berkeley 58 resides in a very interesting low power field with two wide bright doubles to the SE (7.3/10 pair 10' SE and 6.8/10 pair 20' SE) and N7790 and N7788 lie on the same line 20' NW and 35' NW! The striking colored pair, O∑∑ 254, with a beautiful, bright deep red variable (WZ Cas) and a wide bluish companion at 58" is situated 36' S of Be 58. Finally, three mag 6-7 stars also adorn the one-degree field.

Berkeley 82
19 11 20 +13 07.1
Size 4'
Small group of 16-18 stars packed into a 3' circle including three mag 10.2/10.5/11.2 stars at 16"/23" separation on the NW side. A couple of additional faint stars off either end of the trio form an arc and a number of mag 14-14.5 stars follow this arc. A close, faint pair (~6"-8") is on the south end. The two brightest stars are evolved yellow giants (1986 PASP, 98, 218)

Berkeley 85
20 18 47 +37 45.3
Size 5'
Most noticeable is a 4' string of faint stars oriented NW-SE with ~20 stars total resolved at 285x. Near the SE end is a small knot, ~20" diameter, with several very faint stars embedded over haze. A few additional stars follow the SE end. Located in a rich star field with a number of mag 9-10 stars and this cluster does not stand out. Dolidze 41 appears to refer to the same group though may include some nearby brighter stars to the NE.

Berkeley 90
20 35 14 +46 50 48
Size 4'
This small, 3' cluster is mostly huddled around two mag 10.3/10.8 stars oriented NW-SE separated by 1.6'. Near these two stars is a dense group of about a dozen mag 13.5-15 stars with ~18 stars total within 4'. The stars appear to be set over unresolved Milky Way background haze, though I may have been picking up the glow of Sh 2-115, which is envelops the cluster. Located 16' NE of mag 5.8 HD 196178 and 4' following mag 7.7 HD 196331.

Berkeley 94
22 22 53 +55 52.2
V = 8.7; Size 4'
Very distinctive, rich group at 285x located 6' SSW of orange mag 6.5 red supergiant RW Cephei. Includes three mag 10 stars including one that is detached just north of the main group. Many of the stars are arranged in an arrowhead shape or narrow "V" with a second mag 10 star at the vertex on the NE side. Roughly 20 stars are resolved at 285x including several close pairs. The cluster is very rich near the center, around the third mag 10 star. Sh 2-132, a huge HII complex, is located to the NW. It was marginally visible at 73x without a filter as a weak background enhancement in a rich Milky Way field, although it was difficult to confirm with certainty. Excellent contrast gain with an OIII filter as this huge HII region appears roughly 20'x15', elongated in an E-W direction. On the west side, Sh 2-132 encompasses a bright trapezoid of mag 8 and 9 stars (several other mag 11 stars are nearby). The surface brightness is highest just E and SE of this group of stars. The east end tapers down towards mag 8.8 SAO 34340.

Berkeley 95
22 28 18 +59 08.0
Size 5'
Immediately noticed at 105x as a distinctive 4' string oriented N-S with ~15 stars in or near the string. A detached trio of stars on a line to the north would increase the length to 8'. The cluster is located between mag 9.4 HD 239959 6' WNW and a mag 10.8 star 4' E. The group is more easily resolved at 285x with 28 stars, mostly 13-14th magnitude, including a couple of very close faint pairs and triples.

Berkeley 98
22 42 40 +52 24.7
Size 6'
At 285x, roughly 15-20 faint stars (mostly mag 13.5-15) are resolved in a 4' group between two mag 10 stars at the NE end and a mag 10.5 star at the SW end. The group is unimpressive as most of the cluster members are probably too faint to resolve. Located 20' WSW of mag 6.4 HD 215518.

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