Re: 2009 Julian Starfest - Aug 20-23

From: John R Pierce ^lt;pierce_at_No-Spam>
Date: Fri Jul 24 2009 - 11:35:49 PDT

Mark Johnston wrote:

This is at about 4000 feet and is about 35 or so miles North-East from the San Diego lights.   One would think there would be a fair light dome to the South-West but the North and East could be quite nice.

Lassen is at 8000 feet and about 60% or so of the distance to this party from my homestead (very rough guess).

and, it doesn't hurt that Sandy Eggo is at about 32N vs 41N for GSSP.  


OTOH, according to the NA Light Pollution map I'm looking at, Julian is green-to-blue, which is bortle scale 4 bordering on 3, while GSSP is 2 bordering on 1.

Class	Title	Color key	Naked-eye limiting magnitude	Stellar limiting magnitude	Description
1	Excellent dark-sky site	black	7.6-8.0	19 at best	Zodiacal light, gegenschein, zodiacal band visible; M33 direct vision naked-eye object; Scorpius and Sagittarius regions of the Milky Way cast obvious shadows on the ground; Airglow is readily visible; Jupiter and Venus affect dark adaptation; surroundings basically invisible.
2	Typical truly dark site	gray	7.1-7.5	17 at best	Airglow weakly visible near horizon; M33 easily seen with naked eye; highly structured Summer Milky Way; distinctly yellowish zodiacal light bright enough to cast shadows at dusk and dawn; clouds only visible as dark holes; surroundings still only barely visible silhouetted against the sky; many Messier globular clusters still distinct naked-eye objects.
3	Rural sky	blue	6.6-7.0	16 at best	Some light pollution evident at the horizon; clouds illuminated near horizon, dark overhead; Milky Way still appears complex; M15, M4, M5, M22 distinct naked-eye objects; M33 easily visible with averted vision; zodiacal light striking in spring and autumn, color still visible; nearer surroundings vaguely visible.
4	Rural/suburban transition	green	6.1-6.5	15.5 at best	Light pollution domes visible in various directions over the horizon; zodiacal light is still visible, but not even halfway extending to the zenith at dusk or dawn; Milky Way above the horizon still impressive, but lacks most of the finer details; M33 a difficult averted vision object, only visible when higher than 55°; clouds illuminated in the directions of the light sources, but still dark overhead; surroundings clearly visible, even at a distance.
		yellow

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Received on Fri Jul 24 11:36:36 2009