The Gum Catalog

Click on the small images to see larger ones.

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Gum 71

Coordinates: (4.28°, 0.55°)
[ See details ]

This is a ring nebula surrounding the O8 III giant 63 Ophiuchi (HD 162978), which lies at the edge of the Sgr OB1 association in the Sagittarius arm.

You can see the full extent of this huge object in this SuperCOSMOS image.

Gum 72

Coordinates: (6.09°, -1.29°)
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The Lagoon nebula (M8 = NGC 6523-NGC 6530) is
a large HII region mainly ionized by two O-class stars, the ultrahot O4V class 9 Sagittarii and the binary HD 165052 (O6.5V + O7.5V). Sharpless also lists 12 B-stars that may also ionise the nebula. It also includes the radio source W 29.

The Lagoon nebula is a major feature of the Sgr OB1 association in the Sagittarius arm. It is embedded within a molecular cloud which extends to the star cluster NGC 6530. The Hourglass nebula lies within M8’s core. This is a blister-type HII region which has been produced by the O7.5V star Herschel 36.

There is a good image of the the Lagoon nebula here and an amazing wide angle image of the whole region that includes the entire RCW 146 complex and the Trifid nebula.

Gum 73

Coordinates: (6.28°, 23.59°)
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This is an extended HII region around the nearby O9 V star Zeta Ophiuchi. The spectacular bow shock caused by this star as it ploughs through dense dust clouds near the Sco OB2 association can be seen in this infra-red image from the Milky Way Explorer.

Gum 74a

Coordinates: (6.6°, 0.1°)
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This large faint HII region next to the Trifid nebula is ionised by the O9Ib supergiant LS 4551 and the O-class LS 4538, It lies in the direction of the supernova remnant SNR G006.4-00.1 (W 28).

You can view a SuperCOSMOS hydrogen-alpha image.

Gum 74b

Coordinates: (6.89°, -0.93°)
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This is a large area of faint nebulosity lying between the Trifid and Lagoon nebulae. It is ionised by the O9.5/B0 III giant HD 164971 as well as HD 165132 according to Vogt and Moffat. (SIMBAD gives a B5/B6Ib class for HD 165132, too cool to ionise the nebula.)

Gum 75

Coordinates: (7.11°, -2.10°)
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Sh 2-29, Sh 2-31, and Sh 2-32 are a group of three nebulae next to the much larger Lagoon nebula. This group is combined together in the RCW (RCW 146c) and Gum (Gum 75) catalogs.

Gum 76

Coordinates: (7.0°, -0.2°)
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The Trifid nebula, M 20, is an HII region ionised by the O7.5 class multiple star HD 164492 (with seven known components), which is a member of the star cluster NGC 6514. It is divided into three parts by dust lanes. A blue reflection nebula surrounds the HII region.

The Trifid nebula is usually assumed to be part of the Sgr OB1 association in the Sagittarius arm, along with the Lagoon nebula. However, the surprisingly large range of distance estimates for the nebula leaves open the possibility that it lies much further away in the Centaurus arm.

Gum 77a

Coordinates: (8.72°, -0.51°)
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This large diffuse HII region, also called LBN 38, is near the Sgr OB1 association and the Lagoon nebula. According to Sharpless, it is associated with the B1 star HD 165516, which Humphreys places in the Sgr OB1 association. Gum also mentions the Wolf-Rayet star WR 111.

Gum 77b

Coordinates: (10.95°, -1.65°)
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Sh 2-35 and Sh 2-37 are part of a 130 thousand solar mass giant molecular cloud. Sh 2-35 appears along the western edge of this cloud. Sharpless connects this nebula to a number of stars, the hottest of which is the B0 IVPE star HD 312973, which Humphreys locates in the Sgr OB7 association.

SIMBAD reports that HD 312973 is actually an O-class star.

Gum 78

Coordinates: (11.63°, -1.78°)
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Sh 2-37 lies in the direction of the ionising star cluster Dias 5. It is also known as IC 1283/1284 and the powerful radio source W 34.

Sh 2-35 and Sh 2-37 are associated with a 130 thousand solar mass giant molecular cloud and appear to be part of the Sgr OB7 association. Sh 2-37 is visible through a hole in this molecular cloud. This is a very active star formation region.

You can find an infrared image of part of this region here, full colour images here and here, and an analysis of the correct names for these objects here.

Gum 79

Coordinates: (14.2°, -0.1°)
[ See details ]

This huge almost circular nebula is very prominent in hydrogen-alpha as can be seen in this SuperCOSMOS image.

Avedisova concludes that it is ionised by the O6 V star HD 167633. Humphreys places this star in the Ser OB1 association in the Sagittarius arm.

However, several other sources give larger distance estimates, placing this nebula in the Centaurus arm, where it may be part of the Scutum supershell.

Gum 80

Coordinates: (15.18°, 3.33°)
[ See details ]

This isolated nebula is located well above the galactic plane.

Avedisova concludes that it is ionised by the potential runaway O9.5 Iab supergiant HD 165319, which may have been ejected from NGC 6611, the central star cluster of M 16, the Eagle nebula, about 1.8 million years ago.

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Colin Gum, working at Australia's Mount Stromlo observatory in 1951, completed the first major survey of HII regions visible in the southern hemisphere. He published his nebula catalog in 1955. Although Gum's catalog was largely superceded by the RCW catalog published in 1960, many HII regions are still referenced by their Gum numbers even today, so these pages provide an easy reference with cross references to the RCW and Sharpless catalogs.

Most of the images used to illustrate the Gum catalog were created using the SuperCOSMOS Sky Survey, with red = hydrogen-alpha, blue = UKST Blue and green = UKST Infrared. Because green represents infrared, the images are not quite the same as would be seen at purely visual frequencies. Green in these images usually reveals warm dust or red giant stars.

These images were created using the POSS-II/UKSTU data of the Digitized Sky Survey and SuperCOSMOS using the process described here.

According to my correspondence with the Royal Observatory Edinburgh and the Space Telescope Science Institute, I am allowed to use the POSS-II/UKSTU data to create and display images for non-commercial purposes so long as I include this fine print for the SuperCOSMOS data:

Use of these images is courtesy of the UK Schmidt Telescope (copyright in which is owned by the Particle Physics and Astronomy Research Council of the UK and the Anglo-Australian Telescope Board) and the Southern Sky Survey as created by the SuperCOSMOS measuring machine and are reproduced here with permission from the Royal Observatory Edinburgh.

and this acknowledgement taken from the DSS site:

The Digitized Sky Surveys were produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope. The plates were processed into the present compressed digital form with the permission of these institutions.

The Second Palomar Observatory Sky Survey (POSS-II) was made by the California Institute of Technology with funds from the National Science Foundation, the National Geographic Society, the Sloan Foundation, the Samuel Oschin Foundation, and the Eastman Kodak Corporation.

The UK Schmidt Telescope was operated by the Royal Observatory Edinburgh, with funding from the UK Science and Engineering Research Council (later the UK Particle Physics and Astronomy Research Council), until 1988 June, and thereafter by the Anglo-Australian Observatory. The blue plates of the southern Sky Atlas and its Equatorial Extension (together known as the SERC-J), as well as the Equatorial Red (ER), and the Second Epoch [red] Survey (SES) were all taken with the UK Schmidt.

The "Second Epoch Survey" of the southern sky was made by the Anglo-Australian Observatory (AAO) with the UK Schmidt Telescope. Plates from this survey have been digitized and compressed by the ST ScI. The digitized images are copyright © 1993-5 by the Anglo-Australian Observatory Board, and are distributed herein by agreement.

The "Equatorial Red Atlas" of the southern sky was made with the UK Schmidt Telescope. Plates from this survey have been digitized and compressed by the ST ScI. The digitized images are copyright © 1992-5, jointly by the UK SERC/PPARC (Particle Physics and Astronomy Research Council, formerly Science and Engineering Research Council) and the Anglo-Australian Telescope Board, and are distributed herein by agreement.

The compressed files of the "Palomar Observatory - Space Telescope Science Institute Digital Sky Survey" of the northern sky, based on scans of the Second Palomar Sky Survey are copyright © 1993-1995 by the California Institute of Technology and are distributed herein by agreement. The compressed files of the "Palomar Observatory - Space Telescope Science Institute Digital Sky Survey" of the northern sky, based on scans of the Second Palomar Sky Survey are copyright © 1993-1995 by the California Institute of Technology and are distributed herein by agreement.