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Small aperture -- Veil nebula

Started by DrThud, 08/02/2003 06:38PM
Posted 08/02/2003 06:38PM Opening Post
Yet more proof that NGC 6992 is a fairly easy target, given favorable conditions (i.e. L.M. ~6.5 or better, plus reasonable dark adaptation)...

I'd previously seen the eastern arc of the Veil in a pair of Canon 8x32 roof-prism binoculars -- this was at 9000-ft altitude under a ~6.5-mag. Wyoming sky in 2001. By no means was the arc obvious or easily seen; my familiarity with the field certainly helped (I knew where to look). I got the impression, at the time, that an even-smaller binocular *would* indeed show the arc.

This past week, at the Nebraska Star Party, I tried the same experiment with another small binocular. Conditions were very similar -- ~6.5-mag. sky, good dark adaptation. This time, I used a pair of 8x25 Nikon roofs. Again, the view was modest -- a rich field of countless stars, though not very bright or dazzling. I chuckled after noting that, yes, the little Nikons did indeed manage NGC 6992 -- dim as it was. Though the nebula was very subtle, I wouldn't say it was at the threshold of visibility. I think there's more room before "threshold" occurs. If I had to ballpark, I'd think the eastern arc of the Veil *should* be visible in binoculars with sub-20mm apertures.

Next time I experiment, I'll try aperture masks on a few of my binoculars and see just "how low" I can go.

Cheers.
Dan
Posted 08/02/2003 07:28PM #1
Dan, what would really be interesting is to see what the minimum aperture would be through UHC or OIII filters. DR

[COLOR="Blue"]Darian Rachal[/COLOR]
Posted 08/03/2003 02:14AM #2
I'm glad you posted this. It interests me. I've never had much luck with bins smaller than 6x30, but then, I've not tried in skies as dark as you're getting. Generally, I consider binocs under 40mm to be worthless for astronomy, but every now and again it's nice to be reminded that under extremely favorable conditions, nearly any quality optical aid can be put to good use. I wonder if the filter alone would suffice in dark enough skies?

Mike Swaim