Darkness and Light in Musca
The loose globular cluster NGC 4372 dangles at the southern end of the Dark Doodad, an unusually well defined dark cloud just south of the Southern Cross. Stefan Binnewies, Bernd Schröter, Harald Tomsik, and Peter Riepe took this 3°-wide photograph from Namibia with an Astro-Physics 4-inch f/6 refractor. Click on the image to see the entire dark cloud.
Courtesy VdS-Fachsgruppe Astrophotographie
One of the finest dark nebulae, the wonderful, winding, 3°-long Dark Doodad
is a Musca highlight. Interestingly, after observing it at 81x with the 14½-inch, I found that the Millennium Star Atlas
and I had picked the same stars to mark the ends of this dust cloud. It is highly unusual for the boundaries of a large dark nebula to be so definite. Beside the bulbous southern end of the Dark Doodad is the globular cluster NGC 4372
(12h 25.8m -72° 39'). At 136x it was so loosely scattered that it resembled an open cluster, except for its underlying glow. I saw no real patterns to the globular's resolved stars except for an unusual number of pairs. A 7th-magnitude yellow gem highlights the cluster's northwestern margin.
Several Australian amateurs told me not to miss the very unusual Musca planetary nebula NGC 5189 (13h 33.5m -65° 58"), and it turned out to be an unexpected delight. Seen through the 14½-inch at 136x with an oxygen-III (O III) filter, it resembled a barred spiral galaxy, just as Ernst J. Hartung's guidebook, Astronomical Objects for Southern Telescopes, says. Within a large, mottled ellipse of nebulosity, elongated from east to west, there is a brighter northeast-to-southwest arc (the "bar"). An additional knot was spotted beyond the eastern end of the oval. Hartung, who observed with a 12-inch Newtonian, called this knot bluish. John Herschel, the planetary's discoverer, called NGC 5189 "a very strange object."