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Reflection Nebulae in the vdB catalog

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#1 rinalmj

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Posted 10 January 2013 - 12:42 PM

I recently found a copy of the van den Bergh Reflection Nebulae Catalog (as well as his original paper - interesting read) and thought I would try to observe some of the entries. Each entry is given a relative brightness (e.g. medium, bright, etc.) in the catalog. Last night, I attempted to find vdB26, vdB31, and vdB7, which were listed as "medium", "medium", and "bright", respectively. I was unable to detect any of the three. Sky conditions were not ideal, with bad seeing and some thin clouds at times, but they weren't too bad either. I'm wondering if anyone else has had luck with these objects in particular or with the vdB catalog in general.

PS - I was using a Z12 from an orange/yellow zone.

#2 David Knisely

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Posted 10 January 2013 - 01:51 PM

I haven't seen the ones you mention, but most of the vdB objects are very faint and diffuse with little structure visible. About all I see even under dark skies with some of these vdB objects is what looks like a very faint haze around a brighter star. Probably the easiest is the "Iris" Nebula (NGC 7023) in Cepheus (vdB 139). Another one visible right now is in the "head" of the Seagull Nebula: vdB 93 in southern Monoceros, although it is actually a combination of reflection and emission nebulae. Clear skies to you.

#3 GlennLeDrew

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Posted 10 January 2013 - 03:06 PM

You will have read (I seem to recall--it's been years) in his paper that the brightness is based on the appearance in the POSS plates. A photographic brightness for an object whose color differs from the eye's response can be very different indeed.

#4 rinalmj

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Posted 10 January 2013 - 04:04 PM

That's correct, van den Bergh's catalog was developed by studying photographic plates, not through visual observations.

David - thanks for your reply. I'll try the ones that you mentioned someime.

#5 sgottlieb

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Posted 12 January 2013 - 12:26 AM

This thread starting me thinking about what's the easiest vdB reflection nebula that's visible this time, that's *not* in the NGC or IC (such as NGC 7023)?

It's probably either vdB 93, AKA Gum 1, off the northwest tip of the Seagull Nebula (IC 2177) or perhaps vdB 1, which resides just 25' SE of mag 2.2 Beta Cas (Caph). In any case, there are certainly no prominent vdB-only objects.

#6 GlennLeDrew

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Posted 12 January 2013 - 11:12 AM

Steve,
I take it you meant, "...There are certainly no prominent vdB-only objects."

#7 stevecoe

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Posted 13 January 2013 - 02:58 PM

Glenn, Steve, et al;

Here is my observation of vdB 1 in CAS:

vdB 1 13.1" f/5.6 Cherry Rd. Seeing=6 Transp=7
150X--very faint, pretty small, irregularly round, 3 stars of about 8th mag involved. Averted vision helps a lot, the nebula doubles in size when I avert my vision. There are several stars of an equal magnitude nearby, they can be used to provide a test section, which has no nebulosity. The UHC filter makes it disappear, so this is a reflection nebula.

Clear skies;
Steve Coe






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