NGC 2020 = LMC-N57C = ESO 056-148 = DEM L 231

05 33 10 -67 42 54; Dor
Size 2.5′

25″ (4/5/19 – OzSky): at 244x and NPB filter; bright, large, roundish, annular nebula with an easy out-of-round dark hole. The 13th magnitude WR star HD 269748 = Brey 48 (spectral type WN3 + O6.5 III) was easily seen inside the ring, though slightly offset N of center. The rim appeared brighter and a bit flattened along the NW side. In general, the rim was somewhat irregular in surface brightness. Unfiltered, a second fainter star (mag 15.8) was visible at the inner edge of the ring on the SE side.

30″ (11/5/10 – Coonabarabran, 264x): fairly bright, roundish, annular W-R bubble, slightly elongated SW-NE, 3’x2.5′. The inner edge of the annulus was slightly brighter and sharply defined with a relatively large dark center, ~45″ x 30″. The 13th magnitude Wolf-Rayet star HD 269748 = Brey 48 sits north of center inside the ring, though roughly centered within the outer rim of the nebula. A 12th magnitude star lies 1.3′ S of the central star, at the southern edge. Two fainter stars are just north and south of the mag 12 star and this trio is collinear with the central star. NGC 2020 forms a striking due with NGC 2014 (cluster and emission nebula) 5′ WNW. The remarkable Seagull Nebula (NGC 2030, 2032, 2035) lies 15′ NE.

Notes: John Herschel discovered NGC 2020 = h2903 on 30 Dec 1836 and recorded “pB; vL; very gradually little brighter middle; little extended; 4′. A fine cluster [NGC 2014] precedes it.” On the very next sweep he wrote “vF; vL; R; very gradually little brighter middle; 4′ diameter.” His position is accurate.

James Dunlop possibly discovered NGC 2020 earlier in 1826 and described D 218 as “a pretty bright round nebula, 30″ diameter, with a minute star slightly involved in the margin.” Dunlop claims two observations and his position is 5′ too far NE, well within his usual errors. But this nebula is probably too faint to have been picked up by Dunlop with his 9″ reflector and his description could apply to NGC 2014, which is 9′ west of his position. Wolfgang Steinicke attributes Herschel with the discovery and I agree.