Hi All,
Nice highlight of my observing session two nights ago when I slewed the 'scope to IC 1860 just before midnight, expecting to find a galaxy in the eyepiece, to be confronted with over a dozen:The moderately rich galaxy cluster AGCS 301 in Fornax that is just over a degree from the showpiece barred spiral NGC 1097. Here are observing notes made with Brontes: My 63.5cm f/5 Obsession, 12mm TII Nagler at x260 19 arc-min T.F. The SQML reading was 21.95 (taken just a few minutes prior) -- seeing was 7/10.
IC 1860 Gx Fornax
63.5cm x260: IC 1860 is the largest and brightest galaxy, the CD galaxy of AGCS 301. Two other galaxies are there of similar surface brightness and size nearby – IC 1859 6.5’ W and IC 1858 8’ SW. IC 1860 is also surrounded by a small hoard of fainter cluster members mainly to the N and NE as well as two superimposed or near superimposed lesser members. IC 1860 is small to moderate size, elongated in about PA 0, about 1.5' x 1.25', oval with indefinite edges growing weakly to centre where there is a small, moderately brighter round core zone about 15" diameter and occasionally seems to harbor a faint stellaring.
IC 1858 Gx Fornax
63.5cm x260: IC 1858 is the fainter of the three IC galaxies, elongated in about PA 150, 40" x 30" with a compact slightly brighter core zone and occasional stellar nucleus.
IC 1859 Gx Fornax
63.5cm x260: IC 1859 is probably the second brightest and has a magnitude 15.5 star on the outermost SSW edge of the halo. About 1' diameter or slightly smaller, round. Generally has lower S.B than IC 1860, grows broadly and slightly to centre with no apparent core zone or nucleus. S.B isn't too bad without being bright. Moderately faint overall.
PGC 10691 (MCG -5-7-36) Gx Fornax
63.5cm x260: MCG -5-7-36 (PGC 10691) is in the outer halo of IC 1860 about 30" S of centre of IC 1860 and is a tiny 20” x 5" slash in PA 90 of gossamer seen as an enhancement within IC 1860's halo.
PGC 10702 Gx Fornax
63.5cm x260: Like MCG -5-7-36, PGC 10702 is about 30" N of centre of IC 1860 as a very faint diffuse spot of gossamer probably just on the edge of IC 1860s halo.
PGC 10706 Gx Fornax
63.5cm x260: PGC 10706 is 4' N of IC 1860 as a spot of gossamer about 15" diameter rising weakly to centre and PGC 10708 is similar in appearance 6'N.
PGC 10708 Gx Fornax
63.5cm x260: PGC 10706 is 4' N of IC 1860 as a spot of gossamer about 15" diameter rising weakly to centre and PGC 10708 is similar in appearance 6'N.
PGC 10725 Gx Fornax
63.5cm x260: PGC 10725, PGC 10733 and PGC 10746 are in a line to the NE of IC 1860 and are 3’, 4.5’ and 6’ NE of IC 1860 respectively. PGC 10725 is about 15-20" diameter round and growing slightly and broadly to centre without other visible structure.
PGC 10733 Gx Fornax
63.5cm x260: PGC 10725, PGC 10733 and PGC 10746 are in a line to the NE of IC 1860 and are 3’, 4.5’ and 6’ NE of IC 1860 respectively. PGC 10733 is likely second brightest of those close to IC 1860. Elongated in about PA 150, very small 20" x 5" narrow oval of consistent S.B gossamer.
PGC 10746 Gx Fornax
63.5cm x260: PGC 10725, PGC 10733 and PGC 10746 are in a line to the NE of IC 1860 and are 3’, 4.5’ and 6’ NE of IC 1860 respectively. PGC 10746 is a smaller, fainter spot with no structure, about 15" diameter. No other visible structure.
PGC 10687 Gx Fornax
63.5cm x260: PGC 10678 is almost at the mid-point between IC 1860 and IC 1859 is a very faint and tiny spot about 10" diameter rising slightly to centre.
PGC 74222 Gx Fornax
63.5cm x260: PGC 74222 and PGC 74223 are at best about 10" diameter, very faint and very LSB, intermittently visible only. They are E-W of each other, immediately adjacent to each other and 2’ SE of IC 1860.
PGC 74223 Gx Fornax
63.5cm x260: PGC 74222 and PGC 74223 are at best about 10" diameter, very faint and very LSB, intermittently visible only. They are E-W of each other, immediately adjacent to each other and 2’ SE of IC 1860.
PGC 10679 Gx Fornax
63.5cm x260: PGC 10679 is 9' NW of IC 1860 that is about 20" diameter, very LSB and rises weakly to centre with no apparent core or nucleus.
PGC 10744 Gx Fornax
63.5cm x260: PGC 10744 is 7.5' SSE of IC 1860 as a tiny lengthened oval of mist about 20” x 10" in PA 150 with no other visible structure -- consistent S.B.
IC 1860 is central in the attached POSS plate image that is 25' x 20' with N up and W to the right. There is a little variance in recessional velocity between those members that are established cluster members. It would appear to reside just-on the 300 million ly mark.
Best,
L.
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