Object name: HOLMBERG IV
Holmberg IV is a barred irregular galaxy of the Magellanic class that is considered to be a member of the M81 group. Though it is located only 1.5 degrees west-southwest of M101. Redshift puts it about 13 million light-years distant which is about right for the M81 group. However, Tully Fisher measurements put it half again as far at 21 million light-years. This is more in line with the distance to M101. Holmberg did apparently consider it part of the M81 group. Wikipedia considers it part of the M81 group as well. Though I found SEDS considers it part of the M101 group as did one paper listed in the notes at NED. For now, I'll go with its location and non-redshift distance that put it much closer to M101 than M81 both as we see it projected in the sky and as it really is in 3D space if the non-redshift distance is more accurate. Redshift is usually very inaccurate for close in galaxies like this. While Tully Fisher measurements are open to several interpretations they tend to be more accurate at close distances than redshift. To argue the other side; if it is 21 million light-years away its size is a bit over 25,000 light-years. Toward the large end of dwarf status. Moving it to only 13 million light years puts it at 16,000 light-years more typical of a dwarf. But if it is part of the M81 group it lies a minimum of about 7 million light-years from M81 given its distance of 30.6 degrees from M81. That's too far in my opinion to be part of its group. It is a minimum of 477,000 light-years from M 101 assuming the same distance or about 2 to 2.5 million light-years assuming M101 is 23 million light-years away and it is 21 million light-years distant. Thus I'm back to saying it belongs to M101, not M81. If the closer redshift distance is right then it may belong to neither being too far from both.