The Sharpless Catalog

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Sh 2-221

Coordinates: (160.8°, 2.7°)
[ See details ]

This prominent supernova remnant, better known as HB9 (SNR G160.4+02.8), is visible both at hydrogen alpha and radio frequencies.

It is incorrectly listed by SIMBAD as an HII region.

Sh 2-222

Coordinates: (165.36°, -9.02°)
[ See details ]

Also called NGC 1579 and informally the "Trifid of the North", this dusty reflection nebula contains a cluster of about 5 bright B class stars and 35 other stars. The cluster is dominated by the massive young star LkHα 101.

You can see a good image of this nebula here.

Sh 2-223

Coordinates: (165.8°, 2.5°)
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This is the radio source OHIO A 184 (normally referred to in the scientific literature as OA 184).

BFS describe Sh 2-223 as a supernova remnant and reference a 1972 paper, which identifies the object at this location as OA 184. SIMBAD contains separate entries for OA 184 and Sh 2-223 but this appears to be incorrect.

A 2006 paper concludes that OA 184 is not a supernova remnant but an HII region ionised by the O7.5 V star BD +41 1144 at a distance of 2200 +/- 400 parsecs.

Sh 2-224

Coordinates: (166.12°, 4.19°)
[ See details ]

This is the supernova remnant SNR 166.0 +4.3, which is visible at both hydrogen-alpha and radio frequencies.

SIMBAD maintains separate entries for SNR 166.0 +4.3 and Sh 2-224, but this seems incorrect according to the scientific literature.

One study estimates the age as 81 thousand years.

A much better image of this object can be found here.

Sh 2-225

Coordinates: (168.11°, 3.07°)
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The HII region Sh 2-225 contains the young stellar object candidate IRAS 05235+4033 and is ionised by the O9 V star LS V +40 46.

Sh 2-226

Coordinates: (168.48°, -0.97°)
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Little appears in the scientific literature about this nebula. It is more prominent at radio and infrared frequencies than hydrogen-alpha, suggesting that it is visually obscured. Avedisova places it in star formation region SFR 168.48-0.97 with two masers. It is near in the sky to the better studied Sh 2-228 and has a roughly similar distance estimate. Both nebulae appear to lie behind the Aur OB1 association in the outer galaxy.

Sh 2-227

Coordinates: (168.7°, 0.99°)
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Avedisova concludes that this little-studied nebula is ionised by the O9 V star LS V +38 12. It appears behind the western edge of the Aur OB1 association in the outer galaxy.

A much better image appears here.

Sh 2-228

Coordinates: (169.2°, -0.9°)
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Sh 2-228 contains the infrared star cluster [IBP2002] CC01. The 1800 solar mass cluster is 1 to 2 million years old, and the surrounding field stars about 5-6 million years old.

Sh 2-229

Coordinates: (171.97°, -2.18°)
[ See details ]

The Flaming Star nebula (IC 405) is a reflection nebula and HII region ionised by the runaway O9.5Ve class multiple star AE Aurigae.

Research suggests that AE Aurigae was ejected from the Orion star formation region about 2.5 million years ago.

The Skyfactory site has a spectacular image of this region here.

Sh 2-230

Coordinates: (172.97°, -1.31°)
[ See details ]

This enormous diffuse nebula appears in the direction of the Aur OB1 and Aur OB2 associations in the outer galaxy. Only a small detail of this nebula is shown in the accompanying image.

Avedisova lists 3 B-class ionising stars, including the B0.5IV double subgiant HD 35633. She places it in the star formation region 172.97-1.31 along with the infrared source and HII region [DZC2005] Z and the star cluster NGC 1907.

You can view images of this nebula here.

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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.