A Surprise in the Small Sagittarius Star Cloud

by Steve Gottlieb

Last Saturday night (8/12/07) I took another look at two of my favorite Barnard dark nebulae, B92 and B93 with my 18-inch Starmaster. These dark clouds are superimposed on the north side of the magnificent Small Sagittarius Star Cloud. Here's my description from the DARC observatory near Mercy Hot Springs --

Barnard 92
18 15 34 -18 13.8
Size 12'x6'
At 73x, this prominent Barnard dark nebula is very large, elongated N- S, roughly 14'x7' with an extension on the NW side. This is one of the best Barnard objects as it has an unusually high contrast with the surrounding Milky Way in the rich Small Sagittarius Star Cloud. A single brighter star is embedded just east of the center and two bright stars are just off the south (mag 8.8 HD 167336) and east side (mag 7.8 HD 167411).

Barnard 93
18 16 54 -18 04.0
Size 12'x3'
In the same low power field with B92 but not as wide or quite as contrasty. At 73x, appear very large, very elongated SSW-NNE, ~15'x4' with a thin extension to the east off the NE side. The contrast with the Milky Way is very high and sharp on the eastern edge while on the preceding side it nearly merges with B92 in the middle by a couple of meandering darker lanes.

Both objects were easy in my 80mm finder at 25x and I was surprised to also see two very long thin dark lanes that I missed in my 18-inch which extended SW of B92 for 1.5 to 2 degrees. Then on Tuesday night (8/14/07) I was observing again at Lake Sonoma and decided to take a look at NGC 6567, a compact planetary located on the southwest side of the same Small Sagittarius Star Cloud and recorded ...

NGC 6567 18 13 45.2 -19 04 33
V = 10.9; Size 11"x7"
Picked up at 94x as a "bloated" blue star of 11th magnitude. Easy to verify with a UHC blink though only a moderate contrast gain. Situated in a beautiful star field on the southwest side of the Small Sgr Star Cloud. At 260x this high surface brightness planetary displays a 10" disc with a 13th magnitude star barely off the east edge. A very long dark lane (part of B304) crosses the low power field from SW to NE, passing to the north of the planetary.

Before leaving this object I took a look in my 80mm finder at 25x and noticed that this dark lane which passed close to NGC 6567 also extended quite a distance NE until it attached to the southwest side of B92. I realized this was the same long dust lane I noticed two days earlier streaming to the SW of B92!

Checking the Barnard atlas online at http://www.library.gatech.edu/ barnard/index.html I discovered this lane was Barnard 304 (it actually has two forks or lanes on the southwest end) and his description matched perfectly -- "Dusky lanes in star cloud extending toward the SW from B 92 for 1 1/2 degrees." This is a fantastic region to explore with any size scope and I'm sure still holds more surprises.


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Adin, CA

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