[petuniasevan]

The Sagittarius Dwarf Elliptical Galaxy was the subject of this thread:

http://www.freerepublic.com/focus/f-news/988893/posts

And it was an APOD subject back in 1998.

http://antwrp.gsfc.nasa.gov/apod/ap980216.html

[RightWhale]

the dwarf Sagittarius -- which is about 10,000 times the mass of the Milky Way

That is the bothersome part. I assume that is an error, that the Milky Way is much more massive, and denser, too, than the Sagittarius Galaxy.