S-L 360 = HD 35342

05 18 11.4 -69 13 06; Dor
Size 1.1’x1.1′

24″ (4/5/08 – Magellan Observatory, Australia): this small, bright knot is located 2′ due N of S Doradus on the NW side of NGC 1910. At 200x the knot was clearly non-stellar and surrounded by a thin, fainter halo (this corresponds with a faint ring of stars on the DSS). S-L 360 contains three tightly packed blue supergiants and two exceptionally rare WR star of type WO4.

A very bright 3′ patch of nebulosity in NGC 1910 (with several stars) that responds well to a UHC filter is to the east and south of this knot.

Notes: Discovered by John Herschel and called the “chief nucleus” of the cluster. He used the “knot” as the position in three of his observations, and on his last observation he wrote, “It has in it as close double star, easily taken for a nebulous knot (N.B. This is doubtless the knot taken in the three foregoing observations…”

HD 35342, classified as a peculiar spectrum (probably by Fleming or Cannon) in the HD catalogue. It is listed among the 105 objects in the 1960 “The brightest stars in the Magellanic Clouds” by Feast, Thackeray and Wesselink, but noted as a cluster.

S Doradus = HD 35343 = Sk -69 94

05 18 14.3 -69 15 02; Dor
V = 9.7

24″ (4/5/08 – Magellan Observatory, Australia): this is the brightest single star in the LMC and one the brightest, most massive known stars. It appears as a 10th mag star near the center of the NGC 1910 complex. S-L 360, a small bright cluster, lies 2′ N.

Notes: Williamina Fleming classified the spectrum of S Dor as a Type I variable with bright H-beta, H-gamma and H-delta lines. It was reported by Edward Pickering (with credit to Fleming) in Harvard Circular 19 titled “Large Magellanic Cloud”

LMC-N119 = DEM L 130a

05 18 39.2 -69 13 22; Dor
Size 16’x13′

24″ (4/5/08 – Magellan Observatory, Australia): The bright, large, cluster or star cloud NGC 1910 (LH 91) that contains S Doradus (8.6-11.5) is embedded in the very large, bright emission nebula N119.

The most prominent section of the nebula is a very luminous 3′ patch to the east of S-L 360 and a wing to the south of S-L 360 that responds well to a UHC filter at 200x. Nebulosity is also visible on the west side of S Doradus. This section curves N-S to S-L 360 and also south of S Dor. To the south of NGC 1910, a NW to SE stream extends a couple of degrees, containing dozens of LMC clusters including NGC 1903, an impressive globular situated 10′ SW.

NGC 1910 = ESO 056-099 = S-L 371 = LH 41 = LMC-N119

05 18 42.5 -69 14 12; Dor
V = 9.7; Size 10′

24″ (4/5/08 – Magellan Observatory, Australia): this large, bright cluster or star cloud (stellar association LH 41) contains the luminous blue variable (LBV)) S Doradus (8.6-11.5), the brightest star in the LMC and one of the brightest known stars (absolute magnitude -9). At 200x, roughly 100 mag 10.5-15 stars were resolved in a 7′ region with some extensions increasing the diameter another couple of arc minutes. Besides S Dor, there are several 11th and 12th mag A- and B-type supergiants and two Wolf-Rayet (WR) stars. RMC 85, a mag 10.3-10.8 LBV and the 2nd brightest in LH 41, lies just 2′ to the SW of S Dor, in a trio of brighter stars. Brey 21, a mag 11.3 WR binary (WN+B types) lies 3.4′ NNE of S Dor. Several other 12th and 13th mag O and B-type stars in the association have masses from 40-60 M_Sun.

The cluster S-L 360 is 2′ N of S Dor on the NW side of LH 41. It appeared as a small bright knot that was clearly non-stellar. It is surrounded by a thin, fainter halo (a ring of faint stars on DSS). This knot contains three tightly packed blue supergiants and a rare WR star of type WO4 discovered in 2012.

The cluster is embedded in N119, a very large, bright emission nebula. The most prominent section of the nebula is a luminous 3′ patch (involving several brighter stars) to the E of S-L 360 and a wing to the S of S-L 360 that responds well to a UHC filter at 200x. Nebulosity is also visible on the W side of S Doradus. This section curves N-S to S-L 360 and also south of S Doradus. A stream of dozens of LMC clusters extends a couple of degrees to the SE of NGC 1910. In addition, the impressive globular cluster NGC 1903 is 9′ SW and NGC 1916 is 11′ S.

Notes: James Dunlop discovered NGC 1910 = D 129 = D 127 = h2827 on 3 Aug 1826. He described “A pretty large and very ill-defined nebula, irregular round figure, with several stars of some considerable magnitude in it.” His position is unusually accurate. He recorded it again on his second drift of 24 Sep 1826 as D 127: “faint ill defined nebula following a cluster of very small stars – irregular figure branched into small nebulae.” His reduced position was 12′ too far SSW, but it well placed in the drift between NGC 1898 and NGC 1916.

John Herschel first recorded NGC 1910 in Dec 1834 (sweep 523) as a “fine cluster. Irregular figure, the chief nucleus (which seems to be a close double star, 9th mag) taken.” On 15 Dec 1835 (sweep 656) he called it “The most condensed knot (= 12″) in a pretty rich, large, scattered cluster.” The next night (sweep 657), he logged it as “pretty rich large cluster 10′ diameter. It has in it a close triple star, easily taken for a nebulous knot. (N.B. This is doubtless the knot taken in the three foregoing observations…).” I believe Herschel’s “close triple star” may refer to S Dor and its two companions, not S-L 360. In any case, Herschel never specifically mentioned any nebulosity.

In a 1953 paper, Harlow Shapley and Virginia Nail defined NGC 1910 as the center of “Constellation V”, a 24′ region containing numerous blue supergiants.