LMC-N180C = DEM L 322

05 48 14 -70 02 02; Men
Size 1.8’x.1.6′

25″ (4/6/19 – OzSky): at 244x; this emission nebula is part of the NGC 2122 = N180 complex and is situated 4′ NW of the center (about 2′ off the edge of NGC 2122). It was visible unfiltered as a low surface brightness diffuse glow surrounding a mag 13.8 O7-type star.. A mag 14.5/15.5 double star is at the east edge. A mag 11.5 star is 2.4′ NE.

There was a mild enhancement with the NPB filter and the nebulosity appeared moderately bright, round, ~1.3′ diameter, clearly detached from NGC 2122.

Notes: The central star was first identified as an O-type star (MUSE N180-4) in the 2019 paper by McLeod: “Feedback from massive stars at low metallicities: MUSE observations of N44 and N180 in the Large Magellanic Cloud”

LMC-N180A

05 48 37.8 -70 05 57; Men
Size 20″

30″ (10/13/15 – OzSky): N180A is situated at the southwest end of NGC 2122 = N180B, an excellent HII region and cluster. It was noticed at 152x using an NPB filter as a bright, small detached knot, just south of 3 stars on the southwest side of the embedded cluster (LH 117). The 16th mag central star (O8.5 V type) wasn’t seen.

Notes: The central star was first identified as an O-type star (MUSE N180-4) in the 2019 paper by McLeod: “Feedback from massive stars at low metallicities: MUSE observations of N44 and N180 in the Large Magellanic Cloud”

NGC 2122 = LMC-N180B = ESO 057-41 = S-L 731 = LH 117

05 48 53 -70 03 52; Men
V = 10.4; Size 6.0’x4.5′

30″ (10/13/15 – OzSky): Superb HII region and cluster! Unfiltered, at least 3 dozen stars (numerous O-types) were resolved in a 4′ region including several fairly bright 12th mag stars. At the center is HD 270145, the brightest star (mag 12.2), an O7-class binary (19 and 9 solar masses). A mag 13.5 star (05-type) forms a wide pair 0.4′ SE.

The NPB filter provided an excellent contrast gain at 152x! With the filter, the nebulosity (N180B) was very bright and large, round, ~4.5′ diameter, brighter on the SW end and overall displayed an irregular surface brightness with some darker areas.

A bright, small, detached knot (N180A), just south of three stars, is just off the SW side [~2.5′ from center]. NGC 2122 is part of association LH 117 and contains several early O-type stars.

Emission nebula N180C is situated 4′ NW of the center (about 2′ off the edge of NGC 2122). It was visible unfiltered as a low surface brightness diffuse glow surrounding a mag 13.8 O7-type star. A mag 14.5/15.5 double star is at the east edge. A mag 11.5 star is 2.4′ NE. There was a mild enhancement with the NPB filter and the nebulosity appeared moderately bright, round, ~1.3′ diameter, clearly detached from NGC 2122.

Open cluster S-L 740 is 10′ SSE and S-L 769 is 23′ due east. At 394x; S-L 769 appeared large, round, smooth moderate surface brightness, nearly 1′ diameter. A mag 13 star is attached at the east end. S-L 740 appeared fairly faint to moderately bright, round, 1′ diameter, diffuse but uneven or patchy halo. Finally, PGC 3704086, a faint galaxy shining through the LMC, is 3.5′ SE of center.

Notes: James Dunlop discovered NGC 2122 = D 106 = D 107 = h1319 on 3 Aug 1826. He recorded D 106 as “A faint elliptical nebula, about 2′ diameter; slightly condensed to the centre.” D 107, recorded on 24 Sep 1826, was described in his notebook as “a pretty large brightish nebula, irregular figure with a very small star in the center or preceding the brightest part of it – a small nebula detached at the north extremity of this with a small star preceding extemity.” His offsets from the previous objects in this drift are a perfect match.

John Herschel observed this cluster/nebula on 5 sweeps. On 24 Nov 1834 (sweep 513) he logged “B, L nebula, 6′ l, 5′ br; resolved, in part; chief star 11th mag taken.” On 9 Feb 1836 (sweep 673) he noted “cluster, irregular figure, consists of 3 or 4 disjoined clusters, the middle one the largest and brightest; of 3 or 4 large stars and nebulosity; chief star taken.”