The RCW Catalog

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RCW 71

Coordinates: (302.9°, 1.3°)
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RCW 71
RCW 71 is ionised by the O9.5V star CP -60 4312 according to Avedisova (also known as HD 311999) and contains the infrared cluster [DBS2003] 80.

A 2005 study notes that the nebula is surrounded by an emission ring, which can be seen in this MSX infrared image.

RCW 72

Coordinates: (303.2°, 1.6°)
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RCW 72
The RCW catalog describes this as a faint 2 x 2 arcminute region.

According to SIMBAD there are no references in the scientific literature to this object beyond the RCW catalog itself.

This is no visible nebulosity at this location in this image. It seems likely that this nebula does not exist.

RCW 73

Coordinates: (303.4°, 1.4°)
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RCW 73
The dark nebula DCld 303.4+01.4 is near this location, but there is no obvious nebulosity at the RCW 73 coordinates. According to SIMBAD, there is no reference in the scientific literature beyond the RCW catalog itself, which describes it as a medium bright 2x2 arcminute nebula.

It seems likely that this nebula does not exist.

RCW 74

Coordinates: (305.1°, 0.15°)
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RCW 74
GRS 305.40 +00.20 (Kes 18), often named simply G305, is a major star formation region associated with several HII regions, the star clusters Danks 1 and Danks 2, an estimated 31 O stars and the Wolf-Rayet star WR 48a. It may be one of the most massive star formation regions known in the Milky Way.

Avedisova finds three B-class ionising stars, including the B0.5 Iab supergiant HD 114122 and splits the objects in this direction across several star formation regions including SFR 305.25+0.20 and SFR 305.16-0.03. However, Avedisova's information on this region is largely drawn from research published before the true nature of this region was revealed by the MSX and Spitzer infrared space telescopes and would not include the obscured core ionising clusters, which have not yet been properly analysed.

Dutra identifies the infrared star group [DBS2003] 82 and the infrared star clusters [DBS2003] 83 and [DBS2003] 84 in this direction. Although his notes state "not RCW 74" for the clusters, it is not clear what this means as the 3800 parsec distance estimate he gives places the clusters in the same direction and distance as the larger nebular complex.

You can see the full extent of the RCW 74 region in this spectacular Spitzer infrared image.

RCW 75

Coordinates: (306.19°, 0.18°)
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RCW 75
This HII region surrounds and is ionised by the young cluster Stock 16, which is part of the Cen OB1 association and contains the reflection nebula complex VdBH 60a, VdBH 60b, VdBH 60c and VdBH 60d. The region is probably physically connected to the huge and diffuse m Cen nebula.

Kharchenko lists 9 ionising members of Stock 16, including the O stars HD 115455 (O8) and DM -61 3587 (O 9.5 V) as well as 7 B-class stars. She gives a distance of 1640 parsecs and an age of 6 million years.

Dutra places the infrared star group [DBS2003] 86 in VdBH 60b at 2400 parsecs and the infrared star group [DBS2003]85 in VdBH 60d at 2100 parsecs.

Avedisova places this nebula in star formation region SFR 306.20+0.18, along with the emission star IRAS 13168-6208 and the dark cloud Dcld 306.2+0.1.

Although the little documented m Cen HII region is named after the prominent G6 II giant m Cen near its core, it is of course ionised by several much hotter OB stars. Avedisova calls this huge diffuse nebula Ge 136 and lists HD 116796 (O9 V) as the main ionising star, along with two B2 class stars. SIMBAD gives an O9 II class for HD 116796 but curiously appears to be missing the surrounding nebula all together.

You can view a larger image of RCW 75 here and the full extent of the nebulosity (including the huge diffuse m Cen nebula) in this SuperCOSMOS hydrogen-alpha image. You can also see RCW 75 at the edge of the far larger (and twice as distant) RCW 74 nebular complex in this Spitzer infrared image.

RCW 76

Coordinates: (307.2°, -3.5°)
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RCW 76
This is the planetary nebula NGC 5189 = Gum 47 = IC 4274 with the central star KN Mus.

RCW 77

Coordinates: (307.6°, -5.0°)
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RCW 77
This is the Engraved Hourglass planetary nebula, ESO 97-1 = MyCn 18, see a beautiful image of this strange nebula here.

RCW 78

Coordinates: (307.9°, 0.2°)
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RCW 78
This is a ring nebula around the Wolf-Rayet star WR 55.

RCW 79

Coordinates: (308.7°, 0.6°)
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RCW 79
This 1.7 million year old nebula forms a ring around a central ionising star. A 2002 paper identifies the ionising star, which is visible in both hydrogen-alpha and infrared, as either a late O-class star or Wolf-Rayet star but does not cite a catalog identifier.

A magnificent infrared image of this nebula can be found here and a different version (with more infrared frequencies visible) can be found on this Spitzer image.

RCW 80

Coordinates: (309.3°, -0.5°)
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RCW 80
Gum 48d (RCW 80) is an HII region ionised by the B0 IP supergiant HR 5171B, which has as a companion the highly variable G8 Ia supergiant HR 5171A.

Avedisova also lists the B2 Ia supergiant HD 119646 as an ionising star.

SIMBAD follows several sources in identifying RCW 80 with the supernova remnant SNR 309.2-00.6. However, the nebula and the radio peak within the supernova remnant seem to have different locations as can be seen in this Parkes radio image. A 2009 paper states clearly that the HII region and the supernova remnant are two distinct and likely unrelated objects.

RCW 80 can be seen in visual light on this Wikipedia page and in infrared in this Spitzer image.

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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.