The Sharpless Catalog

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Sh 2-201

Coordinates: (138.5°, 1.6°)
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Sh 2-201 is a small HII region adjacent to the Soul nebula, Sh 2-199. It is ionised by the infrared star cluster [BDB2003] G138.50+01.64 which includes an O6-O8 class star, 2MASS J03031615+6027502.

Infrared data suggests that Sh 2-201 is physically attached to Sh 2-199, the Soul nebula, as can be seen in this MSX image.

You can view an interesting radio frequency image of Sh 2-201 here.

Sh 2-202

Coordinates: (140.59°, 1.91°)
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Sh 2-202 is a large diffuse nebula that appears to surround the ionising star cluster Stock 23, which lies in the direction of the enormous Cam OB1 association. According to a 2003 study, Sh 2-201 contains low mass young stellar objects in a carbon monoxide cloud.

Kharchenko gives a distance of 380 pc and an age of 32,3 million years for Stock 23, She lists HD 237091 (B1:V:nnpe) and HD 20134 (B2.5IV-V) as probable members.

Avedisova places Sh 2-202 in star formation region 140.59+1.91 along with the young stellar objects WB89 474 and [TRC83] 5 as well as the infrared source IRAS 03144+5932.

This nebula and some of the ionising stars in this direction can be seen in this false-colour hydrogen-alpha image. You can see a good visual frequency image of Sh 2-202 here.

Sh 2-203

Coordinates: (143.51°, -1.86°)
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This extended diffuse HII region may be ionised by the B class star LS I +55 47. Russeil combines Sh 2-203 with the better known nebula BFS 31 into one star formation region.

Avedisova also combines Sh 2-203 and BFS 31 into the star formation region 143.51-1.86 and in addition adds the HII region Mol 5 and numerous other infrared and radio sources.

You can view a better image of Sh 2-203 here.

Sh 2-204

Coordinates: (145.78°, 2.98°)
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Avedisova says that Sh 2-204 is likely ionised by four O-class stars that are part of the Cam OB3 association. These are BD +56 864 (O6 V), HD 24372 (O9.5 Ib), Hiltner 52 (O7.5 V) and BD +56 866 (O9 V).

The reference to HD 24372 appears to be an error because SIMBAD lists this as a F5V star in a completely different direction. Presumably Avedisova meant HD 237211 as this is a O9.5Iab star in the direction of Cam OB3. SIMBAD gives a cooler B0.5IV class for Hiltner 52.

The distance estimates from Avedisova and Russeil both place this nebula beyond the Perseus arm and possibly associate it with the Norma/Outer arm.
However, a 2005 study connects Sh 2-204 to the much closer Cam OB1 association.

You can see a much better visual frequency image here.

Sh 2-205

Coordinates: (148.54°, -0.24°)
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Both Sharpless and Avedisova list the O9 class multiple star HD 24431 as the main ionising star for the large diffuse Sh 2-205, sometimes called the Peanut nebula. Avedisova also lists two cooler B-class ionising stars.

A recent series of papers divides the nebula into three distinct regions (although at similar distances), with the B-stars ionising a different region than HD 24431. They also suggest that CY Cam (HD 24094) may be an O8.5 or O9 star instead of the usually suggested much cooler B8 and may be the main ionising star of LBN 148.11-0.45 (LBN 696) in this direction.

A 2011 paper states that CY Cam is a B1 III giant.

Like Sh 2-202, this nebula lies at the edge of the Cam OB1 association.

This false-colour hydrogen-alpha image reveals that Sh 2-205 is the brightest region of an even larger nebula.

You can see an infrared image here and a false colour visual frequency image here.

Sh 2-206

Coordinates: (150.6°, -0.9°)
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NGC 1491 is an older, evolved HII region ionised by the O5 star BD +50 886. SIMBAD gives a slightly cooler O6 class for this star.

Contains the infrared star cluster [BDS2003] 62.

A very good visual frequency image of this nebula is available here and a recent WISE infrared image here (Sh 2-206 (NGC 1491) is on the right).

Sh 2-207

Coordinates: (151.2°, 2.1°)
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Despite its appearance, this is an HII region ionised by an O9.5 IV star (MFJ SH 2-207 1) and not a planetary nebula.

Avedisova places Sh 2-207 and Sh 2-208 together in the star formation region SFR 151.32+1.99 along with the radio source KR 198.

Sh 2-208

Coordinates: (151.32°, 1.99°)
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According to the Reed catalog, there are at least three ionising stars in the direction of Sh 2-208: MFJ SH 2-208 3 (O9.5V), LS V +52 19 (O9.5 V) and MFJ SH 2-208 6 (B0V)

The nebula also contains the optical cluster Waterloo 1 and the infrared cluster [BDS2003] 64.

Avedisova places Sh 2-207 and Sh 2-208 together in the star formation region SFR 151.32+1.99 along with the radio source KR 198.

Sh 2-209

Coordinates: (151.6°, -0.2°)
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This large and dusty star formation region in the outer galaxy contains the infrared star cluster [BDS2003] 65.

Avedisova places Sh 2-209 in star formation region 151.60-0.24 with 14 components including a water maser, the young stellar object IRAS 04064+5052 (CPM 12) and numerous infrared and radio sources.

Chini and Wink find three ionising stars: [CW84] S209-1 (B1III), [CW84] S209-2 (O9 III), and [CW84] S209-3 (B1).

This MSX infrared image shows that Sh 2-209 appears to be the brightest spot on the edge of a bubble, which is confirmed by this recent WISE infrared image (Sh 2-209 is at the left).

Sh 2-210

Coordinates: (152.81°, 2.9°)
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There is, remarkably, essentially nothing in the scientific literature about this nebula even though it is prominent in hydrogen-alpha and visible at radio and infrared frequencies as well.

Avedisova places Sh 2-210 in star formation region 152.81+2.90 with four infrared sources and the radio source RRF 1605. None of these objects have any scientific references either.

Sh 2-210 lies in the direction of a larger diffuse nebulosity containing several B-class stars. Sh 2-207, Sh 2-208 and Lynds dark nebula LDN 1407 (Barnard 12) also appear in the direction of this diffuse nebulosity, although apparently are located at different distances.

Navigate to nebula [ Previous | Next ]

Stewart Sharpless published the second and final version of his famous nebula catalog in 1959. Although astronomers publish articles referring to the Sharpless 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 Sharpless objects are clearly visible only in CCD images or in 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 northern hemisphere are in the Sharpless catalog so the 313 objects it contains are well worth examining carefully. (In fact there are more than 313 objects as subsequent research has shown that some of the Sharpless nebulae consist of more than one object.) Although the Sharpless catalog is only intended to be complete for objects visible north of declination -27 degrees, a similar catalog covering the southern hemisphere was published by Alex Rodgers, Colin Campbell, and John Whiteoak in 1960, which is largely an expansion of Colin Gum's earlier catalog. You can visit a gallery of these RCW nebulae here. At least 50 objects in the Sharpless catalog are also in the RCW catalog and I have noted this in the descriptions of these objects.

Most of the images used to illustrate the Sharpless catalog were created using the POSS-II/UKSTU data of the Digitized Sky Survey, or, where available, the more detailed SuperCOSMOS Sky Survey. In both cases, 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.