I haven't thrown out a list of observing challenges in awhile, so here's a
neat galaxy cluster for 12-inch and larger scopes, mostly within 40' of NGC
3158 in Leo Minor. I first ran across this group sometime in the early or
mid '80's after it was featured in a Deep Sky Wonders column by Scotty
Houston and found most of the objects with a 13.1" Odyssey I. I worked
through the cluster using a photo of the cluster (before the days of
computerized sky charts)
William Herschel discovered the brightest two members of the group (NGC 3158
and NGC 3163), but the fainter members were found by Bigourdan using a
16-inch refractor at the Paris Observatory or using Lord Rosse's 72-inch at
Birr Castle. Below the NGC listings are even fainter galaxies for 16-inch or
larger scopes. Finally, there is Shakhbazin 49 in the vicinity -- a compact
cluster of extremely compact galaxies. Good luck!
Steve
NGC 3150 = MCG +07-21-017 = CGCG 211-019
10 13 26.3 +38 39 27
V = 14.5; Size 0.8x0.6
17.5": faint, small, slightly lower surface brightness than N3151 2.3' S. A
mag 12 star is 2.0' WSW and a mag 14 star is 1.8' NNW.
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NGC 3151 = MCG +07-21-018 = CGCG 211-020
10 13 29.1 +38 37 11
V = 13.8; Size 0.8x0.4; SB = 13.5; PA = 170d
17.5": fairly faint, very small, weak concentration. A mag 12 star is 2.0'
NE. Forms a pair with N3150 2.3' N. An extremely faint galaxy is 55" east
of center (2MASXi J1013337+383705).
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NGC 3152 = MCG +07-21-018A = CGCG 211-021
10 13 34.1 +38 50 35
V = 14.2; Size 1.0x0.6; SB = 13.5; PA = 80d
17.5": faint, small, round. A mag 15 star is off the NE edge 0.8' from
center. N3158 lies 5.5' SE and N3160 4.1' E.
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NGC 3158 = U05511 = MCG +07-21-020 = CGCG 211-022
10 13 50.5 +38 45 53
V = 11.9; Size 2.0x1.8; SB = 13.3
17.5": fairly bright, irregular round or slightly elongated, small bright
core. Brightest in N3158 group with N3159 6.7' SSE, N3160 4.7' N and N3152
5.5' NW.
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NGC 3159 = MCG +07-21-021 = CGCG 211-023 = NPM1G +38.0190
10 13 52.8 +38 39 16
V = 13.6; Size 0.8x0.7
17.5": fairly faint, small, irregularly round, small bright core. This
member of the N3158 group is the first of three with N3161 1.2' E and N3163
2.7' E. N3158 lies 6.7' NNW.
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NGC 3160 = U05513 = MCG +07-21-023 = CGCG 211-024
10 13 55.1 +38 50 34
V = 14.4; Size 1.3x0.2; SB = 12.8; PA = 140d
17.5": faint, small, edge-on NW-SE. Member of N3158 group with N3158 4.7' S.
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NGC 3161 = MCG +07-21-022 = CGCG 211-025 = NPM1G +38.0191
10 13 59.2 +38 39 26
V = 13.5; Size 0.8x0.5; SB = 14.8; PA = 10d
17.5": this member in the N3158 group is small and the faintest of three with
close companions N3159 1.2' W and N3163 1.5' E. Even surface brightness and
visible with direct vision.
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NGC 3163 = U05517 = MCG +07-21-026 = CGCG 211-027
10 14 07.1 +38 39 09
V = 13.3; Size 1.1x1.1
17.5": fairly faint, small, round, bright core. Brightest and third of three
with N3161 1.5' W and N3159 2.7' W.
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MCG +07-21-030 = CGCG 211-030 = NPM1G +39.0230
10 14 45.3 +38 58 51
Size 0.6x0.6
17.5": very faint, very small, round, 25" diameter. Picked up while
starhopping to Shkh 49 located 7.4' SE. Located 1.2' NW of a mag 11 star
about 17' NW of N3158.
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2MASXi J1013337+383705
10 13 33.8 +38 37 06
17.5": extremely faint and small. Just visible for moments as a threshold
knot 0.9' E of N3151. A faint star is at the ENE edge. Located in the N3158
group. Verified on POSS.
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2MASXi J1013394+384443
10 13 39.5 +38 44 44
17.5": extremely faint, stellar, estimate V = 16. This anonymous galaxy is a
member of the N3158 group and is located just N of a faint star which is 3'
SW of N3158. Verified on POSS.
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MCG +07-21-019
10 13 47.9 +38 40 32
V = 14.1; Size 0.5x0.4; SB = 12.2
17.5": extremely faint, at visual threshold. Appears similar to the N3159,
N3161, N3163 trio in size but very low surface brightness. Located 2' NW of
N3159 in the N3158 group.
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Shakhbazin 49
10 15 19.0 +38 55 28
17.5": this challenging compact group was a marginal object at 220x-280x. At
220x an extremely faint knot, perhaps 15", was glimpsed several times with
averted vision, using a finder chart. At 280x, there was a strong impression
of two very close 16th+ magnitude stellar objects, though could not view both
objects simultaneously. Located 1.5' NE of a mag 10.5 star and 20' NW of the
N3158 cluster.
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