The RCW Catalog

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RCW 31

Coordinates: (260.7°, -3.2°)
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RCW 28-31 are filaments from the supernova remnant Puppis A (SNR 260.4-03.4). A detailed X-ray image of this region and more on the supernova explosion that created Puppis A can be found here.

RCW 32

Coordinates: (261.38°, 0.84°)
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Near the larger RCW 27 complex, this nebula is probably ionised by the B-class multiple star HD 74804, the brightest member of the star cluster Collinder 197. (SIMBAD gives a B0 V class for this star and lists three components.)

The Diaz et.al. star cluster catalog gives a distance of 838 pc for Collinder 197, so this nebula may in fact be a bit in front of RCW 27.

You can see a spectacular image of RCW 32 / Gum 15 here.

RCW 33

Coordinates: (263.0°, 1.4°)
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There are at least two conflicting distance estimates - one is based on the assumption that this HII region is associated with the star cluster Trumpler 10 at about 400 pc, and the other that it is associated with HD 75759 at about 1000 pc.

You can see a good colour image of RCW 32 and RCW 33 together here, which is linked from Steven Lee's webpage.

RCW 34

Coordinates: (264.4°, 1.4°)
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Much of this nebula, located within the Vela molecular ridge, is obscured by dust. Star formation is taking place at the ionisation front, driven by the O9 Ib supergiant Herb 25 A = VDBH 25 according to Avedisova. She places RCW 34 in star formation region SFR 264.28+1.43 along with 3 masers and the reflection nebulae Bran 206A-D.

RCW 34 includes the infrared star cluster [DBS2003] 28.

Oddly, Herb 25 A appears to be listed in SIMBAD twice. The second duplicate entry is under VdBH 25a.

You can see a good Spitzer infrared image here.

RCW 35

Coordinates: (264.6°, 0.1°)
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Avedisova says that this HII region is ionised by the O7.5 V star CD-43 4690 and 3 B-class stars.

RCW 35 appears to be located at a similar distance as Vela OB1 and is in the same direction as the complex of reflection nebula called Bran 196a-c.

You can see RCW 35 towards the bottom left of this image.

RCW 36

Coordinates: (265.08°, 1.4°)
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The HII region RCW 36 is ionised by a remarkably large and dense star cluster [BDB2003] G265.14+01.45 that is 2-3 million years old and is embedded in the Vela Molecular Ridge Cloud C (VMR C). The cluster has at least 350 members packed within a radius of 0.5 pc. The main ionising star for RCW 36 and the most massive cluster member, [MLG2003] IRS 34 68, is located towards the cluster centre and has a class of O8-O9.

Avedisova places RCW 36 in star formation region SFR 265.12+1.44 with 43 components, including 2 masers, 11 infrared sources, the globule FeSt 2-42 and the reflection nebulae Bran 210A-C.

The RCW 36 cluster can be seen in this 2MASS infrared image.

RCW 37

Coordinates: (266.89°, 0.11°)
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This is NGC 2736, the Pencil nebula.

The filamentary nature of the Pencil nebula strongly suggests an association with a supernova remnant. A 2001 study associates it with the supernova remnant RX J0852.0-4622, also known as the Vela Junior supernova remnant. However, another 2001 study rejects this idea and argues that Vela Junior is located much further away. Even more recent papers suggest that this debate is still unresolved and the distance and age of Vela Junior are both still uncertain.

A rival theory in the scientific literature is that the Pencil nebula is associated with Knot D at the edge of the main Vela supernova remnant.

You can see a beautiful image of the Pencil nebula here and an even more detailed Hubble image here.

RCW 38

Coordinates: (268.03°, -0.98°)
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This giant star formation region at the boundary of the Vela OB1 association is a blister compact HII region lying just inside the edge of a giant molecular cloud. It is ionised by an enormous star cluster, [BDB2003] G267.92-01.06, that is less than 1 million years old and contains about 2000 stars (about 31 of these candidate O or B class stars). The hottest of these is the O5.5V class [FP74] RCW 38 IRS 2.

RCW 38a

Coordinates: (267.92°, -1.01°)
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RCW 38a (Gum 22) is the bright nebula surrounding the O5.5V star [FP74] RCW 38 IRS 2 at the core of the RCW 38 (Gum 23) star formation region.

RCW 38b

Coordinates: (268.01°, -1.05°)
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This small nebula lies near RCW 38a in the massive RCW 38 star formation region. It is divided from RCW 38a by a dust lane and it is possible that it is not a distinct object.

RCW 38c

Coordinates: (267.87°, -0.86°)
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This nebula forms part of the massive RCW 38 star formation region. I can find no ionising star listed in the scientific literature. However, it lies in the direction of the possible OB-star TYC 8156-728-1.

RCW 38d

Coordinates: (268.07°, -0.94°)
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This bubble lies near the ionising star LS 1223 within the massive RCW 38 star formation region.

RCW 39

Coordinates: (269.2°, -1.1°)
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There is little information available in the scientific literature on this mysterious nebula. The Bran catalog identifies RCW 39 with the nebulae Bran 226 and Wray 19-18 and finds two CO clouds with distinct velocities in this direction.

Avedisova places RCW 39 in star formation region 269.11-1.08 along with Gum 12a, three masers and the multiple Wolf-Rayet star gamma Velorum. If these associations are correct, RCW 39 is a fairly local object and not at a large distance of 3000 pc as other estimates suggest.

RCW 39 is prominent in infrared, as can be seen in this MSX 8μm image, as well as at radio frequencies as this Parkes image shows.

RCW 40

Coordinates: (269.3°, -1.4°)
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This HII region appears to be part of the Vela OB1 association and according to Avedisova is ionised by the O9 V star CD -48 4352.

This MSX infrared image reveals a spectacular bubble structure. This 2MASS infrared image strips away the dust surrounding this nebula and shows the central star cluster.

Both SIMBAD and the RCW catalog identify RCW 40 and Gum 25 and I have kept that identification here given the limited accuracy of Gum's coordinates. However, there is an unusually large distance between the two sets of coordinates suggesting the possibility that they are distinct.

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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.