M81's satellite galaxy Holmberg IX (UGC 5336, DDO 66)

Irregular Galaxy Holmberg IX (UGC 5336, DDO 66), type Im, in Ursa Major

Right Ascension 09 : 57.5 (h:m)

Declination +69 : 03 (deg:m)

Distance 12000 (kly)

Visual Brightness 16.5 (mag)

Apparent Dimension 1.4 (arc min)

Discovered by Sidney van den Bergh in 1959.

Right Ascension	09 : 57.5 (h:m)
Declination	+69 : 03 (deg:m)
Distance	12000 (kly)
Visual Brightness	16.5 (mag)
Apparent Dimension	1.4 (arc min)

In this magnification from an excellent amateur image of M81, faint companion Holmberg IX (UGC 5336) is visible.

This image was created by Martin Germano with his self-made 14.5" f/5 Newtonian.

More images from Martin Germano

This galaxy was first listed by Sidney van den Bergh and cataloged by him as DDO 66 (Van den Bergh 1959). Dwarf galaxy Holmberg IX was first so called in Eric Holmberg's study of groups of galaxies (Holmberg 1969). A formal description of this and another M81 group dwarf was first provided by Bertola and Maffei (1974). It is an irregular galaxy of so-called Magellanic type (i.e., similar to the Magellanic Clouds), closely resembling Local Group galaxy IC 1613.

SIMBAD data for Holmberg IX

NED data for Holmberg IX

Publications on Holmberg IX (NASA ADS)

References

F. Bertola and P. Maffei, 1974. Two Faint Companions to M81. Astronomy and Astrophysics, Vol. 32, pp. 117-119 (April 1974) [ADS: 1974A&A....32..117B]
Eric Holmberg, 1969. A study of physical groups of galaxies. Arkiv för Astronomii, Vol. 5, No. 20, pp. 305-343 [ADS: 1969ArA.....5..305H]
Sidney van den Bergh, 1959. A catalogue of dwarf galaxies. Publications of the David Dunlap Observatory, Vol. 2, No. 5, pp. 147-150 [ADS: 1959PDDO....2..147V]

Hartmut Frommert
Christine Kronberg
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Last Modification: April 27, 2007