[AJames]

Dugnsuz

The "Coathanger Asterism" or "Brocchi's Cluster" (Cr 399 - Collinder ) you refer too is in Vulpecula - however, it is not really a northern object as the position is RA: 19h 25.4m Dec. +20deg 11min.

For your interest, an excellent discussion can be found at ;
http://www.greenwich-observatory.co.uk/coathanger.html.

Also a nice image appears at;
http://celestialwonders.com/Cr399_20061009.html

As a general comment, the original question here talks about northern objects - things we can't see but know of. But the real question seems more on what a northern object is! My definition is what can be seen from southern latitudes divides the sky into;

Northern skies (+90 deg to +60 deg N) (invisible from Sydney)
Southern skies (-90 deg to -60 deg)
Equatorial skies (+30 deg N to -30 deg S)

The regions between +30 deg and +60 deg and -30 deg and -60 deg, I would assume to be the horizon constellations seem from either hemisphere, which some objects can be seen from mid-latitudes in the observers hemisphere.
In some ways they are not really northern objects as I can see them from home near the horizon.

I suppose to be pedantic, the northern skies could be considered as +90 deg to +45 deg, southern -90 deg to -45 deg and the rest of the sky we share among us as common sky ground.

If the aequator of the sky was counted as southern, then we can claim the Orion Nebula is a southern object because it lies 5 degrees south of the equator! (A northerner would literally "sent us all to hell" before they let us have that wonderful object, don't you think? )

Nyx