The RCW Catalog

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RCW 121

Coordinates: (348.2°, -1.0°)
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RCW 121
Infrared imagery reveals that RCW 121 (Sh 2-4) and RCW 122 lie at the edge of an enormous bubble ionised by the star cluster Havlen-Moffat 1. This cluster is 2-4 million years old and contains the Wolf-Rayet stars WR 87 and WR 89 as well as several O-stars.

RCW 122

Coordinates: (348.9°, -1.1°)
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RCW 122
RCW 121, RCW 122 and RCW 123 are probably ionised by stars in the Havlen-Moffat 1 cluster. There is a large and very uncertain range of distance estimates for the objects in this direction, from 2000 to 5000 parsecs.

A 2012 study used radio parallax to determine the distance to a maser in the direction of RCW 122 as 3380 parsecs, strongly implying that this is the distance of the entire Havlen-Moffat 1 star formation region.

RCW 122 separates into at least two distinct sources in infrared. The brightest one by far is IRAS 17167-3854, which is sometimes further subdivided into RCW 122A and RCW 122B. Dutra and colleagues locate the infrared cluster [DBS2003] 119 in this direction at 2000 parsecs. A distinct smaller nebula to the northwest in galactic coordinates is IRAS 17158-3901, also known as RCW 122C. These sources are ionised by several O-stars, including one as bright as O4.

A 2008 paper concludes that RCW 121 and RCW 122 are embedded in a 1.2 million solar mass molecular cloud and both nebulae are likely ionised by several O7 V class stars.

The larger region around RCW 121, RCW 122 and RCW 123 is spectacular in infrared. This Spitzer image shows only a part of this region. While not as detailed, this MSX image shows a wider view of the region in which the compact HII regions RCW 121 and 122 are seen to be bright knots at the rim of a vast star forming cavity centred on the ionising cluster Havlen-Moffat 1 and filled by the diffuse HII region RCW 123.

RCW 123

Coordinates: (349.5°, -0.8°)
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RCW 123
RCW 121, RCW 122 and RCW 123 are probably ionised by the cluster Havlen-Moffat 1. The large diffuse nebula RCW 123 is in the same direction and almost the same distance as WR 89 in the cluster Havlen-Moffat 1.

The RCW catalog cross references this object with the Sharpless object E6 = Sh 1-6 = Sh 2-5. The locations given for Sh 2-5 and RCW 123 differ considerably but this is not surprising because this is a huge diffuse nebula. The RCW catalog further notes that this object is a "Loop".

This large scale SuperCOSMOS image confirms that Sh 2-5 and RCW 123 are different locations within a huge diffuse nebula prominent in hydrogen-alpha.

The larger region around RCW 121, RCW 122 and RCW 123 is spectacular in infrared. This Spitzer image shows only a part of this region. While not as detailed, this MSX image shows a wider view of the region in which the compact HII regions RCW 121 and 122 are seen to be bright knots at the rim of a vast star forming cavity centred on the ionising cluster Havlen-Moffat 1 and filled by the diffuse HII region RCW 123.

RCW 124

Coordinates: (349.7°, 0.8°)
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RCW 124
This is NGC 6302, the Bug nebula, the remains of a dying G V class star. You can see an amazing Hubble image of this planetary nebula.

RCW 125

Coordinates: (350.0°, 0.2°)
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RCW 125
The RCW catalog identifies this little-studied object as a faint 8 x 8 arcminute nebula.

It lies in a similar direction to the HII region GAL 350.10+00.09, which is mostly visible in the infrared.

Avedisova concludes that it is ionised by the O7 V class star HD 322987.

RCW 126

Coordinates: (350.6°, 1.0°)
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RCW 126
RCW 126 is a faint extended nebulosity surrounding the cometary nebula GM 1-24. At the heart of GM 1-24 is a cluster of more than 25 stars with a total stellar mass of 100-400 solar masses embedded deep in a dense molecular cloud of 40 thousand solar masses.

The RCW catalog identifies RCW 126 and BBW 31800a. Avedisova places RCW 126 in star formation region SFR 350.48+0.98 with 21 components, including GM 1-24 and 2 masers.

Dutra et.all find 3 infrared groups within RCW 126: [DBS2003] 121, [DBS2003] 122 and [DBS2003] 123.

RCW 127

Coordinates: (351.23°, 0.77°)
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RCW 127
This is NGC 6334, the Cat's Paw nebula. This complex of HII regions contains one larger bubble (Gum 63) adjacent to three smaller bubbles (Gum 61, Gum 62 and Gum 64b) in addition to several other partially obscured nebulae and at least eleven major infrared sources that are probably mostly cooler B stars.

It lies at the same distance as NGC 6357, the War and Peace nebula, and is separated from it by a dark cloud. Both are near the Sco OB4 association in the Sagittarius arm.

RCW 128

Coordinates: (351.4°, -0.1°)
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RCW 128
According to Avedisova, RCW 128 is ionised by the O7 III class LSS 4126. Cameron Reed agrees with this spectral class, although oddly SIMBAD gives a far cooler F8 class for this star.

RCW 129

Coordinates: (351.9°, 12.7°)
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RCW 129
This huge and very faint HII region surrounds the nearby B0 V star Tau Scorpii, one of the brightest members of the Sco OB2 association.

You can see a spectacular image of the entire Sco OB2 region, dominated the red supergiant Antares. RCW 129 is the faint reddish nebula towards the top of the image.

RCW 130

Coordinates: (352.44°, 2.26°)
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RCW 130
This mysterious nebula, catalogued as RCW 130 and Sh 2-10, lies in the direction of the Sco OB4 association. Two Wolf-Rayet stars, WR 86 and WR 88, are visible towards its edge.

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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.