20° wide open cluster on TriAtlas?

[jnb]

I was printing off some of the triatlas pages this afternoon and noticed that there appears to be a huge circle marked on the B4 and B5 pages. According to the key it is an open cluster centered on RA 14h40m, dec +70° (roughly), but it's about 10° in radius and it doesn't appear on the A series.

What is this feature?

[Moonshane]

It's marked as Collinder 285

http://en.wikipedia.org/wiki/Ursa_Major_Moving_Group