…continuedSeeking Summer's Dark Nebulae
M24, the Small Sagittarius Starcloud, harbors twin dust clouds, Barnard 92 and 93, visible in 7x50 binoculars. The two perch near the northern edge of M24, where they are very dramatic in my 8-inch f/6 Newtonian at low power. In such a telescope, the lone 12th-magnitude star in B92 is an islet in a black lake outlined by the rich star swarms of M24. B92 is 15' by 10'. In superb skies both my 8-inch and my 4-inch Astroscan can trace dark streams commencing at the western shore of B92. The longest stream can be followed 1° to the southwest edge of M24. Narrower B93 lies about 1/3° east of B92.
Occasionally I can see hints of the amorphous dark structures that photographs show between B93 and the eastern margin of the starcloud. All amateurs have favorite objects that they enjoy introducing to others. Many times I've enjoyed listening to neophytes' reactions when they're shown B92 and B93 for the first time.
Some of the best dark nebulae for 4- to 8-inch telescopes are found near the glorious open cluster M11 in the Scutum starcloud. The Barnard 114-118 complex begins ½° southeast of M11. From there it runs southward about 1°. Sweeping the cluster's vicinity will reveal other contrast features. Coal-black, 1°-wide Barnard 103 is 3° west of M11 midway between Alpha and Beta Scuti, at the edge of the Great Rift.
Two of the easiest dark nebulae are B142 and B143, about 1½° west-northwest of Gamma Aquilae. They outline most of a 1°-high capital E, shown readily by 7x50 binoculars even in suburban skies. Burnham's Celestial Handbook says: "Appearing not merely as a starless area, it actually gives a strong impression of an obscuring mass suspended between the observer and the star-strewn background."
Here is a list of some selected Barnard Objects that observers will find interesting. Many are mentioned in this article.
|B59, 65, 66, 67||17h 21m||-27°||7° long|
|B86||18h 03m||-27°||4.5' x 3'|
|B92||18h 15m||-18°||15' x 10'|
|B93||18h 17m||-18°||12' x 2'|
|B103||18h 39m||- 7°||60'|
|B114-118||18h 53m||- 7°||50' x 5'|
|B142, 143||19h 41m||11°||80' x 50'|
|B168||21h 53m||47°||100' x 10'|
|B352||20h 57m||45°||20' x 10'|