This M81 companion is a dwarf irregular or Magellanic system discovered by Sidney van den Bergh in 1959 and is similar to IC 1613. Holmberg IX has the youngest mean stellar population age of any nearby galaxy and may be a young tidal dwarf assembled from gravitational collapse of gas and stars stripped off during the last close encounter of M81 with M82 (see http://arxiv.org/PS_cache/arxiv/pdf/0802/0802.4446v1.pdf)

900/1200mm - 48" (4/15/10): Holmberg IX is located just 10.5' E of the center of M81. With this dwarf galaxy centered in the eyepiece, the outer halo of M81 was visible near the edge of the field. At 330x Holmberg IX appeared very faint, fairly large, 2' diameter, round, low even surface brightness with no noticeable concentration. The galaxy is nestled within a kite asterism including a mag 13 star 1.3' S.

Notes by Steve Gottlieb