The Herschel Objects

[acey]

Back in the 1970s James Mullaney proposed a deep-sky observing list consisting of William Herschel's catalogue, minus the 2,000 or so objects in Class II (faint) and Class III (very faint), leaving around 600 objects. Mullaney describes it in this book:

http://www.amazon.co.uk/Herschel-Objects-How-Observe-Them/dp/0387681248/

If you feel like trying it, Herschel's complete catalogue can be found here:

http://seds.org/Messier/xtra/similar/h2500a.html

Just cut out all the H2 and H3 objects and you'll have the list.

The "Herschel 400" list (http://www.astroleague.org/al/obsclubs/herschel/h400lstc.html) is a selection from the complete Herschel catalogue - it includes many Class II and III objects (as does the "Herschel 400 number 2" successor list, linked to in the "How Messy Are You?" thread). The nice thing about Mullaney's original suggestion is that it consists of all the objects that Herschel himself rated brightest.

Just for info, Herschel classed objects as follows (data taken from Mullaney):

Class I - Bright nebulae (288 objects)

II - faint nebulae (909)

III - very faint nebulae (984)

IV - Planetary nebulae (78)

V - very large nebulae (52)

VI - Very compressed and rich clusters (42)

VII - compressed clusters of faint and bright stars (67)

VIII - coarsely scattered clusters (88)

These have little scientific meaning now: most of Herschel's "nebulae" are galaxies, and his "planetary nebulae" include globular clusters as well as what we would now call planetaries. His numbering system got overtaken by the NGC catalogue, but for deep sky observers they're very valuable, because they convey a sense of what the object actually looks like like.

I can thoroughly recommend Mullaney's book - and the "Herschel 600" - to anyone looking for deep-sky targets beyond the Messier list. All are viewable with an 8-inch scope (or less) from a dark site. I think I'm around half way through - and don't expect to finish any time soon.

Herschel, apparently, discovered his first 1,000 or so objects in a year and a half...

Andrew

[Sam]

Herschel, apparently, discovered his first 1,000 or so objects in a year and a half...

Very interesting post Andrew - I guess Herschel had better weather than we have now!!