The RCW Catalog

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RCW 51

Coordinates: (286.0°, 0.5°)
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The HII region RCW 51 surrounds the massive young (8-9 million years) star cluster NGC 3293 and both in turn appear to be located in a similar distance and direction as the giant molecular cloud Sodroski 62.

Kharchenko lists 16 ionising B-class stars as probable members, the hottest of which is the B0 Ia supergiant HD 91969. She gives a distance of 2471 parsecs and an age of 8.7 million years. The entire complex lies near the Car OB1 association.

I've sometimes referred to this striking cluster/nebula combination as the Eye of Horus. You can view a more detailed image of the cluster here.

RCW 52

Coordinates: (287.2°, 0.4°)
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The RCW catalog describes RCW 52 as a "Bright knot in η Carina nebula separated from main region by absorption".

This ring nebula is ionised by the O8 V star LSS 1887. Avedisova adds two additional B-class ionising stars. It is viewed next to the vast clouds of the Eta Carinae nebula (RCW 53) and may be nearby if the Avedisova estimate is correct or much further away if the Cameron Reed estimate from 1993 is correct.

Avedisova places RCW 52 together with the Eta Carinae nebula (RCW 53) and Gum 31, Gum 32, and Gum 33 in the massive and complex star formation region SFR 287.28-0.88 with 143 components.

You can view a good image of this nebula here.

RCW 53

Coordinates: (287.61°, -0.85°)
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The Carina nebula, NGC 3372, is ionised by star clusters belonging to the massive Car OB1 association, which includes some of the brightest known stars in the Milky Way: 20 O-stars, 4 ionising B-stars the Wolf-Rayet star WR 25 and the massive and very strange variable star Eta Carinae.

The Car OB1 member HD 93129A is perhaps the brightest known star in the Milky Way and has been put into its own O2 class.

Kharchenko identifies about a dozen ionising clusters in this direction. Nine of these have distance estimates ranging from about 2000 to 3000 parsecs: Trumpler 14, Trumpler 15, Trumpler 16, Bochum 10, Collinder 228, NGC 3324, NGC 3293, Loden 153 and [KPR2005] 62. Distances are controversial, however, even for such a well-studied region. For example, a 2004 paper argues that Trumpler 16 is a background object at 4000 parsecs.

The Hubble space telescope has produced a huge panorama of the Carina nebula.

RCW 54

Coordinates: (289.4°, -0.6°)
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This enormous nebular region lies in the direction of the Car OB2 association and parts of it may be ionised by stars in that association. Gum splits this region into several distinct nebulae and the RCW catalog itself splits the region into four subnebulae, which are described separately as RCW 54a, 54b, 54c and 54d.

RCW 54a

Coordinates: (289.90°, -1.26°)
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This HII region is associated with the giant molecular cloud [GCB88] 13 and according to Avedisova is ionised by the Wolf-Rayet star WR 35.

Dutra et.al report the infrared cluster [DBS2003] 57 in this direction.

You can see a detailed colour image in this direction here.

RCW 54b

Coordinates: (289.26°, 0.28°)
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RCW 54b lies in the direction of (and may be identical to) the HII region / reflection nebula NGC 3503, surrounding the star cluster Pismis 17, which includes one B0 V and three B2 V stars.

Gum 34a and Gum 34b are bright filaments in the RCW 54b region..

You can see a close up image of NGC 3503 here.

RCW 54c

Coordinates: (290.61°, 0.33°)
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Gum 37, also called RCW 54c, is associated with the star cluster NGC 3572.

You can see a good colour image of this region here.

RCW 54d

Coordinates: (290.42°, 1.68°)
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Also called Bran 347, the HII region Gum 36 (RCW 54d) is ionised by the B0 V class star HD 97471.

RCW 55

Coordinates: (290.4°, -3.0°)
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This HII region is associated with one O8 V and six B-class stars according to Pinheiro et.al.. It lies in the midst of the Carina arc, about half way between the Car OB2 association and the massive star formation region RCW 49.

Avedisova identifies 4 ionising stars: the O6 V CP -62 1824, the O7.5 III giant HD 95589, the B0 V VdBH 45C, and the B1 IV subgiant CP -61 2000. She places RCW 55 in the star formation region SFR 290.28-3.01 with a methanol maser, the small nebulae Bran 323, Bran 328b, Bran 331 and Bran 332, the dark cloud DCld 289.8-03.2 and the star cluster Graham 1.

RCW 56

Coordinates: (291.1°, -2.1°)
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Avedisova places the faint nebula RCW 56 in star formation region SFR 291.01-2.08 with the nebula Bran 339. These objects have the same coordinates and appear to be the same nebula.

Bran 339 contains the infrared cluster [DBS2003] 60.

RCW 57

Coordinates: (291.6°, -0.5°)
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RCW 57 is actually two distinct objects at different distances: NGC 3576 (Gum 38a) and NGC 3603 (Gum 38b). SIMBAD and some scientific papers mention a RCW 57a and 57b but in fact the RCW catalog does not subdivide the nebulosity in this direction.

RCW 58

Coordinates: (292.4°, -4.9°)
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This is a ring nebula surrounding the Wolf-Rayet star WR 40. The ring has a mean radius of 2.5 pc and is expanding away from the central star at a speed of 90 km/s

A good hydrogen-alpha image of this nebula can be found here.

RCW 59

Coordinates: (293.0°, 4.5°)
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The filaments of the extended nebula RCW 59 may be associated with the Car OB2 association. They do not appear to be visible in this DSS-2 image however. (The RCW catalog says that this nebula is a huge 3 degree loop.)

A 2008 study concludes that RCW 59 is probably a supernova remnant rather than an HII region.

On the earlier assumption that this was an HII region, Avedisova identified two potential B-class ionising stars: the B0 III giant HD 99890 and the B 2Iab-Ib supergiant HD 99939.

You can see this faint loop in this SuperCOSMOS hydrogen-alpha image.

RCW 60

Coordinates: (293.7°, -1.4°)
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Part of the Lambda Centaurus nebula complex (centred around RCW 62). This is actually 2 distinct nebulae at different distances: Gum 39 and Gum 40.

Avedisova combines RCW 60, RCW 61 and RCW 62 into one large star formation region, SFR 293.64-1.41 with 51 components.

RCW 60a

Coordinates: (293.59°, -1.26°)
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This bright nebula is centred around the O6 V HD 99897 and corresponds to the "head" of the Running Chicken nebula complex.

Gum associates Gum 39 with HD 99897 but gives a B5 class, too cool to ionise the nebula. Cameron Reed, the Georgelins and SIMBAD all give a much hotter O6 class, making it likely that this is the main ionising star.

RCW 60b

Coordinates: (293.70°, -1.60°)
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There are several knots of nebulosity in this direction, which correspond to the "wattles" of the Running Chicken nebula complex, below the "head", Gum 39 (RCW 60a).

Gum associates Gum 40 with the nebula IC 2872 and the star HD 99898. He gives a B8 class for this star, too cool to ionise the nebula. However, Cameron Reed gives a B2/5 III class and SIMBAD (following the Georgelins) gives a much hotter O9 V, making it more likely that this is the ionising star.

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Alex Rodgers, Colin Campbell, and John Whiteoak, working at Australia's Mount Stromlo observatory under the direction of Dutch-American astronomer Bart Bok, published their nebula catalog in 1960. The RCW catalog is largely an expansion of Colin Gum's 1955 catalog. Although astronomers publish articles referring to the RCW nebulae almost every month, there seems to be few places on the Internet that bring together information on these nebulae as a whole - unlike, for example, the Messier catalog. This is most likely because the Messier objects are visible to anyone with a pair of binoculars or a small telescope. Most of the RCW objects are clearly visible only in long exposure CCD images or photographic plates taken by large telescopes. Fortunately some of these plates have now been digitally scanned and made publicly available.

Many of the brightest and most beautiful Milky Way star formation regions visible from the southern hemisphere are in the RCW catalog so the 182 objects it contains are well worth examining carefully. (In fact there are more than 182 objects as subsequent research has shown that some of the RCW nebulae consist of more than one object.) At least 50 objects in the RCW catalog are also in the Sharpless catalog and I have noted this in the descriptions of these objects.

Most of the images used to illustrate the RCW 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.