The Deepsky: Top-100

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Deepsky Top-100 (15): M104, Stargate and Jaws

Near the Corvus-Virgo border lies M 104, the Sombrero-galaxy, a spiral galaxy that was discovered by Mechain in 1781. M 104 is a magnitude 8 galaxy, with a diameter of 8'x4'. Its surface brightness is 11, so it is a relatively bright galaxy. I was astonished how easily I could detect and observe it with direct vision using my 8-inch telescope, especially from my own backyard, where the southern sky is completely light polluted.

I used two fine asterism from Phil Harrington's book "The Deepsky, an introduction" to locate M 104. The asterisms are called Stargate (Harrington STAR 20) and Jaws (Harrington STAR 21), and I can tell you that together with M 104 these two asterisms form a splendid trio of deepsky objects that are easy to find, even for un-experienced observers.

Start at Corvus (the Raven), a distinct trapezoid of bright 3rd magnitude stars southwest of Virgo. Locate Delta Corvi and Eta Corvi, a pair of stars at the north-eastern corner of Corvus. Centre your finder scope on Eta Corvi. From there go north for about 3 degrees. You will find a triangle of stars in your finder scope, again pointing in north-eastern direction, at two fainter stars, which stand closely together. These two stars are part of Harrington's STAR 20, Stargate.

Finder chart for M104, Stargate and Jaws. Limiting magnitude 7.5
Credit and copyright SkyTools 2 by Capellasoft

Click here to download a printable finder chart (PDF)

Centre your field of view on Stargate and try several magnifications until you clearly see two triangles of stars as on the sketch below. The sketch (to the right) of Stargate was made on April 18th 2003, using my 8-inch TAL 200K and a 12mm Vixen Lanthanum eyepiece. The field of view is 18' and the magnification is 166x. North is up and west is to the left.

From Stargate we go to Jaws and M 104. Centre Stargate in your eyepiece. Now you can use a low power eyepiece instead of the finder scope. Go about 1 degree northeast and you will find Jaws together with M 104. Harrington STAR 21 is called Jaws because the asterism resembles a shark swimming in southern direction, the two brighter stars marking the head and mouth. The rest of the line of stars form the shark's body, while the lonely star to the west marks the dorsal fin.


Just to the right of Jaws you will find M 104 within a triangle of bright stars. On the evening of April 18 2003 I could detect M 104 very easily. It looked like a small elongated hazy patch of light with a sort of bulge to one side. However, I could not detect any details, but unfortunately this is almost always the case with galaxies observed from my backyard with the 8-inch. I really have to go to a dark-sky site to see some more details in galaxies. The sketch to the right was made using the 8-inch Klevtzov-cassegrain and a 32mm Televue plossl. The field of view is 46' and the magnification is 62.5x. North is up and west is to the left.

Jaws and M 104

This fantastic trio should be on everyone's observing list. I can recommend them to all of you, so go out and hunt them down! They are very fine objects to observe.

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