CONSTELLATIONS OF THE MONTH - The Large Magellanic Cloud

Albert Brakel

Two years ago we looked at the Small Magellanic Cloud, and this month we are tackling a much heftier job, its big brother the Large Magellanic Cloud, also known very occasionally as Nubecula Major. It is the largest satellite galaxy of the Milky Way, and it sprawls across the constellation boundary between Dorado and Mensa. To give some idea of the huge scope offered by the LMC, it contains over 200 NGC objects, about 900 clusters from the Shapley-Lindsay catalogue, and about 220 emission nebulae from the Henize catalogue. Obviously this is a far greater wealth of riches than you get in the average constellation, and in spite of the length of this article, I can give only a small sampling of what is available. In trying to include the best objects, I mostly relied on the Herald-Bobroff Astroatlas charts D03-D04, E01-E08, and F01-F04, and made what I hope is a representative selection.

The obvious starting point is the biggest and brightest object, the Tarantula Nebula, but with such an abundance, where do you go from there? I decided to go south from the Tarantula along a trail of prominent objects, and then zig-zag clockwise around the rest of the Cloud. Navigating through this jungle of treasures is a bit of a problem, and is no doubt one of the factors that intimidates many observers from looking at the LMC in detail (another being the lack of readily available comprehensive descriptive guides). The best way of dealing with the navigation issue is to use a goto telescope, so I used the Society's 14-inch Meade SCT on Mt Stromlo. While this did not give me the darkest possible sky, it was adequate, and better than any sky over suburbia. Mostly I used a magnification of 137x, as many of the vistas deserve a reasonably wide field of view, but where necessary I bumped the power up to as much as 296x, except for my last night, when seeing conditions only permitted powers up to 178x or 237x. So, let's get started!

The Tarantula Nebula (NGC 2070) (RA 05h 38.7m, Dec -69° 06') is so well known as one of the best of all deep sky objects that it hardly needs description. At its centre is a compact open cluster of young, giant blue stars, including the massive 30 Doradus. Around this is arrayed a series of striking, well-defined luminous loops, that give the nebula its name. Further inspection discloses a slew of glowing clouds in the surrounding area, with some obvious dark patches. You've probably all heard the mind-boggling facts about the Tarantula - it is the only nebula in another galaxy easily visible to the unaided eye, if it was as close as the Orion Nebula it would cover about 30° of sky and be three times as bright as Venus, and it is the largest emission region that we know of in the entire Universe (although we don't know most of the Universe as well as our cosmic backyard).

Before going on to other bright objects, try moving 20' to the SW past NGC 2044 (an unremarkable loose group of 6 stars) and check out the site of SN 1987a (05 35.5, -69 16), where Hubble images show that the blast wave from the supernova has reached a shell of material previously ejected from the progenitor star and is making it glow. I detected a tiny dim fuzzy spot with averted vision, and an OIII or any other filter made no difference.

NGC 2100 (05 42.0, -69 14) is a compact group of 5 brighter and some fainter stars, set in emission nebulosity that was confirmed by OIII and UHC filters.

NGC 2074 (05 39.6, -69 26) has stars in a rough reverse-S shape set in nebulosity that is well brought out by the OIII and UHC. The nebulosity is brightest at the E end.

NGC 2080 (05 39.8, -69 38) appeared as a bright nebulous patch even without the filters (but enhanced with them). To its SE lie NGC 2085 surrounding a prominent star, and NGC 2086, both smaller nebulae that are dimmer than NGC 2080.

NGC 2078 (05 39.7, -69 45) is a nebulous patch not as bright as NGC 2080. The dimmer and diffuse nebulosity to the NE with some stars embedded is Henize 159.

South of the Dorado-Mensa constellation border, at the eastern end of the prominent bar of the LMC, NCG 2058 and NGC 2065 (05 37.0, -70 13) are two open clusters lying in the same field of view with 296x. Both are roundish unresolved hazes, NGC 2058 being bigger and dimmer, while NGC 2065 is brighter, more concentrated and smaller. The filters found no nebulosity.

NGC 2075 (05 37.7, -70 40), an open cluster, appeared as a small roundish patch in which the filters indicated nebulosity present.

NGC 2018 (05 30.4, -71 04) turned out to be a broad dim region of nebulosity spangled by stars. A knot on the N side is by far the brightest part. The view was enhanced by both filters.

Back into Dorado, open cluster NGC 2136 (05 52.8, -69 29) resembled a bright, tight, round unresolved haze, sitting in a triangle of field stars. There was a negligible response from the nebular filters.

NGC 2159 (05 57.8, -68 38), another bright open cluster, has a concentrated core surrounded by the faint sparkle of barely resolved stars in its outer halo (using 137x and 296x). It forms a nice triangle with two other clusters to the NE (NGC 2164 and NGC 2172) that are of comparable size but dimmer. There were no OIII responses, indicating there is no nebulosity involved.

NGC 2027 (05 35.0, -66 55), a small, bright, concentrated, unresolved cluster, again showed no significant nebulosity.

NGC 2032 (05 35.3, -67 34) - wow! This magnificent relatively large and bright rectangular area of nebulosity is bisected by a dark N-S lane. There are two stars on the W side. It shows up really well with the UHC and OIII filters, which also bring out a dimmer continuation of the nebulosity towards the W. A separate small nebulous patch to the E is NGC 2040, which contains some barely-resolved embedded stars.

NGC 1966 (05 26.8, -68 48) appeared as irregular nebulosity surrounding a handful of brighter stars and several fainter ones. UHC and OIII both brought out the nebula well, but I preferred the UHC for overall aesthetic effect because the stars came out looking better.

NGC 1937 (05 22.3, -67 52) is a largish open cluster of middling and fainter stars with complex nebulosity. Six brighter nebulous knots stand out with the filters, one on the S side being particularly bright.

NGC 1873/1869/1871 (05 13.7, -67 24) form a north-to-south line 10' S of Theta Doradus. They are three small impoverished clusters with some nebulosity, a bit disappointing after the previous object.

NGC 1866 (05 13.3, -65 27) represents the furthest north we are going in this survey. It is a bright round cluster, partly resolved with 178x. What's interesting is that it has been cited as the brightest of the so-called "blue globulars", objects resembling globular clusters but consisting of young, hot blue stars instead of red and yellow ageing ones, and having no counterparts in the Milky Way Galaxy. NGC 1866 is plotted on the chart as an open cluster, suggesting a revision of its classification.

NGC 1818 (05 04.2, -66 24), another "blue globular" plotted as an open cluster, showed as small, bright, tight and round. At 137x it was resolved around the edges and had a grainy middle. 296x power was able to resolve the rich concentrated centre.
The NGC 1763/1769/1773 (04 56.8, -66 24) area is an outstanding field of two major (NGC 1763 and 1769) and one minor (NGC 1773) nebulae spangled by stars. NGC 1763 is roughly elliptical (or kidney or bean-shaped if you prefer), while the other two are more rounded. All three have stars immersed in them. The major two are very bright with both filters, though still fine and obvious without them. Adjacent to the S of NGC 1763 is the star cloud NGC 1761 with only dim nebulosity. Beautiful!
NGC 1714 (04 52.1, -66 55) appears as a loose, sprawling, sparse cluster of mainly middling, faint an unresolved stars, to the SE of which is a small tight knot of bright nebulosity.

NGC 1829 (05 04.8, -68 03) - just to the NW of a mag. 8 star lies this small concentrated cluster of just-resolved (137x) faint stars, set in a somewhat wider, dim nebulosity.
The next three objects lie on the extension of the western end of the prominent bar of the LMC.

NGC 1736 (04 53.0, -68 03) is a small, moderately bright emission nebula, enhanced by both filters. A pair of bright stars is located 8' to the WSW in the same 137x field.

NGC 1755 (04 55.0, -68 11) was seen as a small, very compact cluster, resembling a globular in shape. The brighter stars in the centre were just resolved with 296x.

IC 2117 (04 57.0, -68 24) is an open cluster of scattered medium-brightness stars, closely adjacent to the brightest knot of nebulosity in the wider nebulous region of NGC 1770 extending to its NW.

NGC 1910/SL 360 (05 17.0, -69 13), in the central region of the prominent bar of the LMC. There is confusion as to what these designations refer to. The HB Astroatlas plots NGC 1910 as a small, bright cluster just west of the larger, dim SL 360, but Hartung referred to it as an extended star cloud. Jenny Kay researched this (SC Feb 1999 p5) and found that Herschel had given the NGC 1910 designation to two objects, the small cluster SL 360 and the larger cluster it resides in. The latter would be Hartung's star cloud. Through the telescope, the star cloud is a fine vista of medium to faint stars, irregularly dense, with the brightest member being the bright (mag. 9) luminous variable S Doradus. There is a denser patch in the star cloud NE of S Dor. The small cluster SL 360, at low magnification, looked like an unresolved bright, roundish, nebulous spot, 30" across, resembling a planetary nebula in general appearance. With 237x though, some stars were resolved in it.

NGC 1903 (05 17.2, -69 20 ), some 8' SW of SL 360, showed as a bright, round cluster, resembling a globular, and was just resolved around the edges with 237x.

NGC 1874/1876/1877/1880 (05 13.3, -69 23). Two small knots of nebulosity (NGC 1877 and 1880) occur on the S edge of an area of faint to middling stars (NGC 1876) that are all immersed in the dimmer nebulosity of NGC 1874.

The NGC 1743/1748 group (04 53.9, -69 12) has two small, fairly bright nebulae surrounding stars. A third, yellow, non-nebulous star makes a right-angled triangle with them. There is a wider dim nebulosity in the field, especially extending to the SW.

IC 2105 (04 49.4, -69 12) is a very small, rounded, concentrated nebula, resembling a planetary nebula, near a mag. 11 star. It was enhanced by both filters. In the same field 4' to the NW, lies the dim but noticeable open cluster SL 45, that was unresolved by 137x, and invisible with both filters (hence there is no associated nebulosity).

IC 2111 (04 51.9, -69 24) resides in a nice field of nebulae set in a star cloud extending SW-NE. It is the bright, small, round, discrete nebulous knob W of a mag. 9 star. To its N by 4' is the strongly nebulous elliptical open cluster NGC 1727, with several stars resolved at 137x.

Back into Mensa, NGC 1711 (04 50.6, -69 59) appeared as a small, elliptical, bright, rich open cluster, resolvable around the edges with difficulty using 178x power in degraded seeing.

Henize 191/SL 209 (05 04.6, -70 54) was revealed as a dim, smallish, nebulous patch with two medium-brightness stars embedded, and situated in a wider triangle of stars. The nebulosity responded to the UHC filter, but poorly to the OIII, indicating that there is more hydrogen-beta than oxygen-III light being emitted. Some 10' to the N in a low power field lies NGC 1833, a small open cluster enveloped in nebulosity that responds to the UHC; a dimmer nebula lies just to its SW. Just N of NGC 1833 is the larger and fairly loose cluster NGC 1837.

NGC 1848 (05 06.9, -71 11) - the last stop on our tour - comprising another small, compact, moderately bright open cluster, needed a magnification of 296x to be just resolvable in the prevailing seeing.

Pick of the bunch
For those with small 'scopes, or affected by moderate light pollution, or who only want to see the half-dozen best ones, I recommend trying the following: NGC 2074, NGC 2080, NGC 2032, NGC 1763/1769, NGC 1910, and, of course, the Tarantula.

This report has gone on longer than I originally intended, but with such a plethora of treasures it was hard to force myself to stop. I am reminded of what Clive of India said when replying to charges about the scale of his plunder in Bengal in 1757: "An opulent city lay at my mercy. Vaults were thrown open to me alone, piled on either hand with gold and jewels. At this moment I stand astonished at my own moderation!"