7 May 2018
Australian astronomer Colin Gum (1924-1960) was based at Mt Stromlo in the 1950s, and he catalogued emission nebulae in the southern sky using wide field photography. Gum published his findings in 1955 in a study entitled A study of diffuse southern H-alpha nebulae which presented a catalogue, now known as the Gum Catalogue, which contains 84 emission nebulae. Although Gum’s catalogue was largely superseded by the RCW catalogue published in 1960 many HII regions are still referenced by their Gum numbers today. And from the elusive Gum 6 – the Vela SNR – to the handful of small, faint and challenging Gum nebulae, they offer an intriguing night’s viewing.
Gum has the largest emission nebula in the whole sky named after him. With a diameter of 36° the Gum Nebula (Gum 12) sprawls across the constellations of Puppis and Vela, and lies 1,470 light-years away. A more fitting monument to a cosmic cloud hunter who died way too young could not be imagined.
Unfortunately, the enormous Gum Nebula is not visible to our backyard telescopes. The only way to see it is to look at photos of it.
Relatively little is known about the origin of the vast nebula, although it is thought to be the remnant of a supernova explosion one million years ago. The 11,000-year-old Vela Supernova Remnant (encompassing 8 degrees) appears to be embedded in this nebula, although the two are considered separate objects. (Interestingly, the Gum Nebula was photographed during Apollo 16’s 1972 voyage to the Moon while the command module was in the double umbra of the Sun and Earth, using high-speed Kodak film.)
Here are a few of the small, faint and elusive Gum beauties:
Name | Other designations | Right Ascension | Declination |
Gum 1 | IC 2177 | 07 04 25.0 | -10 27 18 |
Gum 2 | RCW 1, Sh 2-296 | 07 09 20.2 | -10 20 47 |
Gum 3 | RCW 1a, Sh 2-297 | 07 05 16.7 | -12 19 34 |
Gum 4 | NGC 2359, Thor’s Helmet | 07 18 30.0 | -13 13 36 |
Gum 5 | RCW 6, Sh 2-301 | 07 09 42.0 | -18 26 00 |
Gum 6 | RCW 7, Sh 2-302 | 07 31 18.0 | -16 58 00 |
Gum 7 | RCW 12, Sh 2-307 | 07 35 32.9 | -18 45 33 |
Gum 8 | RCW 15, Sh 2-310 | 07 21 00.0 | -25 12 00 |
Gum 9 | NGC 2467 | 07 52 18.5 | -26 25 41 |
Gum 10 | RCW 19 | 08 16 16.8 | -35 37 58 |
Gum 11 | NGC 2579 | 08 20 55.3 | -36 13 23 |
Gum 12a | Gum Nebula | 08 09 31.9 | -47 20 11 |
Gum 12b | Gum Nebula | 09 49 00.0 | -38 24 00 |
Gum 13 | RCW 29 | 08 21 54.0 | -42 39 00 |
Gum 14 | RCW 27 | 08 39 09.5 | -40 25 09 |
Gum 15 | RCW 32 | 08 43 52.5 | -41 14 39 |
Gum 16 | Vela SNR | 08 33 00.0 | -44 06 00 |
Gum 17 | RCW 33 | 08 50 21.0 | -42 05 23 |
Gum 18 | RCW 35 | 08 51 48.0 | -43 51 00 |
Gum 19 | RCW 34 | 08 56 28.1 | -43 05 58 |
Gum 20 | RCW 36 | 08 59 00.9 | -43 44 10 |
Gum 21 |
| 08 54 59.1 | -47 35 32 |
Gum 22 | RCW 38a | 08 59 06.0 | -47 30 00 |
Gum 23 | RCW 38 | 08 59 42.0 | -47 27 00 |
Gum 24 | RCW 39 | 09 02 42.0 | -48 20 00 |
Gum 25 | RCW 40 | 09 02 21.3 | -48 41 55 |
Gum 26 | RCW 42 | 09 24 30.1 | -51 59 07 |
Gum 27 | NGC 2899, RCW 43 | 09 27 03.0 | -56 06 21 |
Gum 28 | NGC 3199, RCW 48 | 10 16 32.8 | -57 56 02 |
Gum 29 | RCW 49 | 10 24 14.6 | -57 46 58 |
Gum 30 | NGC 3293, RCW 51 | 10 35 52.8 | -58 13 52 |
Gum 31 | IC 2599 | 10 37 42.0 | -58 39 00 |
Gum 32 | RCW 52 | 10 46 11.5 | -58 39 12 |
Gum 33 | NGC 3372, Carina Nebula, RCW 53 | 10 45 02.2 | -59 41 59 |
Gum 34a |
| 10 58 00.0 | -59 42 00 |
Gum 34b |
| 11 03 12.0 | -59 32 00 |
Gum 35 | RCW 54a | 10 58 50.9 | -61 06 38 |
Gum 36 | RCW 54d | 11 12 07.0 | -58 48 14 |
Gum 37 | RCW 54c | 11 10 02.3 | -60 05 42 |
Gum 38a | NGC 3576 | 11 11 49.8 | -61 18 14 |
Gum 38b | NGC 3603 | 11 15 10.8 | -61 15 32 |
Gum 39 | RCW 60a, Running Chicken head | 11 28 54.1 | -62 39 09 |
Gum 40 | RCW 60b, Running Chicken wattle | 11 28 51.9 | -62 55 51 |
Gum 41 | RCW 61, Running Chicken feet | 11 30 24.3 | -63 49 0 |
Gum 42 | IC 2944, RCW 62, Running Chicken body | 11 38 20.0 | 0 -63 22 22 |
Gum 43 | RCW 65 | 12 34 54.4 | -61 39 25 |
Gum 44 | RCW 66 | 12 35 42.0 | -61 52 00 |
Gum 45 | RCW 69 | 12 44 27.4 | -62 31 18 |
Gum 46 | RCW 71, Bran 397 | 12 50 22.6 | -61 35 00 |
Gum 47 | RCW 76, NGC 5189 = IC 4274 | 13 33 32.8 | 8 -65 58 27 |
Gum 48a | RCW 75 | 13 19 46.0 | -62 30 42 |
Gum 48b | RCW 78 | 13 33 18.0 | -62 18 00 |
Gum 48c | RCW 79 | 13 39 54.0 | -61 45 00 |
Gum 48d | RCW 80 | 13 47 00.0 | -62 35 00 |
Gum 49 | RCW 98, Coffee Bean Nebula | 15 55 39.6 | -54 38 36 |
Gum 50 | RCW 99 | 15 59 28.4 | -53 44 57 |
Gum 51 | RCW 105 | 16 10 00.0 | -49 08 00 |
Gum 52 | RCW 107, NGC 6164/6165 | 16 33 52.3 | -48 06 40 |
Gum 53 | RCW 108, NGC 6188 | 16 40 00.1 | -48 51 45 |
Gum 54 |
| 16 54 12.0 | -45 12 00 |
Gum 55 | RCW 113 | 16 53 00.0 | -42 12 00 |
Gum 56 | RCW 116 | 16 56 54.6 | -40 30 44 |
Gum 57a | RCW 119 | 17 01 13.0 | -38 12 11 |
Gum 57b | RCW 119, Sh 2-2 | 17 03 56.7 | -37 50 38 |
Gum 58 | RCW 120, Sh 2-3 | 17 12 24.0 | -38 28 00 |
Gum 59 | RCW 123 | 17 19 48.0 | -38 16 00 |
Gum 60 | NGC 6302, RCW 124, Sh 2-6 | 17 13 44.5 | -37 06 11 |
Gum 61 | NGC 6334, Cat’s Paw Nebula | 17 19 46.0 | -36 05 48 |
Gum 62 | NGC 6334, Cat’s Paw Nebula | 17 20 52.7 | -36 07 52 |
Gum 63 | NGC 6334, Cat’s Paw Nebula | 17 19 30.4 | -35 42 36 |
Gum 64a |
| 17 20 06.0 | -35 58 00 |
Gum 64b | NGC 6334, Cat’s Paw Nebula | 17 20 54.0 | -35 53 00 |
Gum 64c | NGC 6334, Cat’s Paw Nebula | 17 20 12.0 | -35 45 00 |
Gum 65 | Sh 2-9 | 16 21 11.3 | -25 35 34 |
Gum 66 | NGC 6357, RCW 131, Sh 2-11 | 17 24 44.4 | -34 12 11 |
Gum 67 | RCW 132, Sh 2-12 | 17 34 42.4 | -32 34 53 |
Gum 68 | RCW 133, Sh 2-13 | 17 29 12.9 | -31 32 03 |
Gum 69 | RCW 134. Sh 2-1, W25 | 17 49 16.5 | -31 15 18 |
Gum 70 | RCW 137, Sh 2-16 | 17 46 42.0 | -29 18 00 |
Gum 71 | RCW 144, Sh 2-22, LBN 14 | 17 54 54.0 | -24 53 13 |
Gum 72 | M8 = NGC 6523-NGC 6530, RCW 146a, Sh 2-25,Lagoon Nebula | 18 03 36.0 | -24 20 00 |
Gum 73 | Sh 2-27 | 16 37 09.5 | -10 34 01 |
Gum 74a | RCW 145, Sh 2-28 | 18 01 00.0 | -23 20 00 |
Gum 74b | RCW 146b | 18 04 42.1 | -23 27 35 |
Gum 75 | RCW 146c | 18 09 17.6 | -23 59 18 |
Gum 76 | M20, Trifid nebula, RCW 147, Sh 2-30 | 18 02 23.5 | -23 01 50 |
Gum 77a | RCW 169, Sh 2-34, LBM 38 | 18 15 30.0 | -21 38 00 |
Gum 77b | RCW 151, Sh 2-35, LBM 42 | 18 16 30.0 | -20 24 00 |
Gum 78 | RCW 153a, Sh 2-37 | 18 17 39.9 | 9 -19 40 19 |
Gum 79 | RCW 157, Sh 2-44 | 18 16 49.6 | -16 31 04 |
Gum 80 | RCW 158, Sh 2-46 | 18 05 58. | -14 11 52 |
Gum 81a |
| 18 21 18.0 | -16 13 00 |
Gum 81b |
| 18 19 54.0 | -15 57 00 |
Gum 82 | RCW 162, Sh 2-48 | 18 22 24.0 | -14 34 00 |
Gum 83 | M16, Eagle Nebula, NGC 6611, RCW 165, Sh 2-49 | 18 19 00.0 | -13 52 00 |
Gum 84 | NGC 6604, RCW 167, Sh 2-54 | 18 18 00.0 | -11 57 00 |
Gum 85 |
| 18 17 54.0 | -11 44 00 |