Which major star parties have Bortle Class 1 skies?

The Bortle Dark-sky scale:

http://www.skyandtelescope.com/resou...tml?page=2&c=y

--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 14th Annual NEBRASKA STAR PARTY *
* July 15th-20th, 2007, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************

David Knisely wrote:
Greg, I don't recall seeing you at the Nebraska Star Party. What year
did you attend?

When did I say I had? Although I have planned to go on several
occasions something always seems to come up.


--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)

SkyTools: http://www.skyhound.com/cs.html
Observing: http://www.skyhound.com/sh/skyhound.html
Comets: http://comets.skyhound.com

To reply take out your eye

"David Knisely" wrote in message
...
The Bortle Dark-sky scale:

http://www.skyandtelescope.com/resou...tml?page=2&c=y


She just don't know what she's talkin about

David Knisely wrote:
The Bortle scale is rather inconsistent and uses some gages which are
not commonly possible to use, especially towards the faint end.

Yeah, that's for sure. Another one that gets me is "your telescope,
companions, and vehicle are almost totally invisible." This brings up
what I believe to be the heart of the problem; the whole question of
what a "dark" sky really means. Eventually transparency dominates.
After all, the darkest sky is one where the sky is completely overcast!

To my way of thinking after the point where most light pollution has
been avoided the question is no longer one of darkness, but one of
transparency. Bortle also defines a class 1 sky thus: "The Scorpius and
Sagittarius region of the Milky Way casts obvious diffuse shadows on the
ground." But obviously this is at odds with the statement that
everything around you is almost totally invisible. In fact, in my
experience, a transparent sky away from lights is rather bright--so
bright that you can often see your surroundings fairly well.

It's too bad this scale wasn't created by someone who has common access
to dark and transparent skies. On that end it really suffers and sounds
more like the description of an imagined perfect sky rather than a real one.

Clear skies,
Greg

--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)

SkyTools: http://www.skyhound.com/cs.html
Observing: http://www.skyhound.com/sh/skyhound.html
Comets: http://comets.skyhound.com

To reply take out your eye

Alvan et al....

I believe in giving credit where credit is due...

Mr. Bortle has done a lot of good work over the years and
no one else came up with a suitable scale...at least that I know of.

Having been at the 9,000 ft level (Visitors Center) of Mauna Kea, I
would have
to think that it is a 1 on the Bortle Scale.

From Cherry Springs (which can't be much worse than Mauna Kea) you can
see
M33 naked eye. The Milky Way appears at dusk and grows brighter as
twilight turns into night. Clouds, when they appear, look like dark
blobs because there is very little uplight.

Interestingly enough, Cherry Springs caught the eye of someone in the
Travel section of the New York Times last week:

http://travel.nytimes.com/2007/09/14...ml?ref=escapes

Better get up there and down to Spruce Knob if you have never been
because both sites are being eyed for Wind Farm development.

When did I say I had? Although I have planned to go on several occasions something always seems to come up.


Well, after the initial post (which specifically mentions the skies of
NSP along with a few others), you wrote:

In my experience the difference between Bortle 1 and Bortle 2 is much more about the current weather conditions than the level of light pollution. In other words, there are not any places in the continental US that are truly Bortle 1 except on a few exceptional nights.

Thus, I would have assumed that, from your statement, you had
experienced the skies of the area around Merritt Reservoir where the
star party is held. Obviously, you have not. This might account for
your initial rather blanket declaration that "there are not any places
in the continental US that are truly Bortle 1". There are a number of
sites in the U.S. (mostly in the western half) where skies that fulfill
many if not most of the stated Bortle 1 characteristics do occur. A
number show such sky quality on a fairly frequent basis, although
perhaps not on every night. Regular attendance at some of the western
star parties is enough to show many amateurs that these sites do deliver
a Bortle 1 and/or Bortle 2 level of dark sky. I consider the site of
the Nebraska Star Party to be at least "potential" Bortle 1 (if not
actual), as long as the weather conditions are reasonably clear. Clear
skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 14th Annual NEBRASKA STAR PARTY *
* July 15th-20th, 2007, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************

David Knisely wrote:
When did I say I had? Although I have planned to go on several
occasions something always seems to come up.

Well, after the initial post (which specifically mentions the skies of
NSP along with a few others), you wrote:

In my experience the difference between Bortle 1 and Bortle 2 is much
more about the current weather conditions than the level of light
pollution. In other words, there are not any places in the
continental US that are truly Bortle 1 except on a few exceptional
nights.

Thus, I would have assumed that, from your statement, you had
experienced the skies of the area around Merritt Reservoir where the
star party is held. Obviously, you have not. This might account for
your initial rather blanket declaration that "there are not any places
in the continental US that are truly Bortle 1".

I thought at first you were just being nice. I don't wish to argue with
you David. I believe what I said stands on its own. Your unfortunate
attempt to suggest that I don't know what I'm talking about because I
haven't been to one particular star party is really rather disrespectful
and does not merit further comment.

There are a number of
sites in the U.S. (mostly in the western half) where skies that fulfill
many if not most of the stated Bortle 1 characteristics do occur.

Yeah, I know. I live in one. You'd think that in all the years we have
been conversing you'd have noticed that!

A
number show such sky quality on a fairly frequent basis, although
perhaps not on every night. Regular attendance at some of the western
star parties is enough to show many amateurs that these sites do deliver
a Bortle 1 and/or Bortle 2 level of dark sky. I consider the site of
the Nebraska Star Party to be at least "potential" Bortle 1 (if not
actual), as long as the weather conditions are reasonably clear. Clear
skies to you.

In fact I pretty much said exactly what you said above. The key
sentence was the one you left out: "In my experience the difference
between Bortle 1 and Bortle 2 is much more about the current weather
conditions than the level of light pollution."

As you have pointed out the Bortle 1 class is inconsistent and poorly
defined. See my second post on the matter for a more long winded
explanation of what I meant. The short version is this: once the sky
reaches a certain level of darkness it isn't about darkness anymore,
it's about transparency. Surely we can agree on that? No hard feelings?

Clear skies,
Greg

--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)

SkyTools: http://www.skyhound.com/cs.html
Observing: http://www.skyhound.com/sh/skyhound.html
Comets: http://comets.skyhound.com

To reply take out your eye

Greg Crinklaw posted:

I thought at first you were just being nice. I don't wish to argue with you David. I believe what I said stands on its own. Your unfortunate attempt to suggest that I don't know what I'm talking about because I haven't been to one particular star party is really rather disrespectful and does not merit further comment.

I may have read too much into what you initially said. Your posting
alleging that there were no true Bortle 1 sites right after the initial
poster mentioned at least one where that does happen seemed to indicate
that you were dismissing the possiblity of Bortle 1 at NSP completely
without having been there (and I wanted to make certain that you had not
been there). This seemed a little unfair.

In fact I pretty much said exactly what you said above. The key sentence was the one you left out: "In my experience the difference between Bortle 1 and Bortle 2 is much more about the current weather conditions than the level of light pollution."

Well, I didn't really leave anything out as I quoted the paragraph
exactly and then commented about the portion of your statement which I
found inaccurate. The problem was the use of an absolute which seemed
to imply that there were *no* sites that produced the characteristics of
a Bortle 1 site except on very rare nights. If you had not said this in
the way you did, then I would probably have not objected to it.

I agree that the Bortle scale is not all that great (too many levels,
too little consistency on what characteristics or gages should be
applied, etc.), but in at least the limiting magnitude figures, it is at
least approximately valid. For me, however, I would probably use a bit
simpler set of levels to gage sky quality (use of averted vision assumed
for magnitudes fainter than 5.0:

SEVE only stars brighter than mag. 4.0 are visible with bright
skyglow over
most of the sky.
MODERATE: mag. 4.0 to 4.9 stars visible (variable skyglow depending on
direction of observation).
MILD: mag. 5.0 to 5.9 stars visible (some notable darker areas
visible).
DARK SKY: mag. 6.0 to 6.8 stars visible (dark, sometimes with a few light
domes along the horizon).
PRISTINE: mag. 6.9 and fainter stars *consistently* visible (little or no
light pollution in any direction).

There might be room to add in an "extreme" category, but I think
something like these levels would about cover things. Clear skies to you.

--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 14th Annual NEBRASKA STAR PARTY *
* July 15th-20th, 2007, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************

David,

As I recall, M33 is a naked eye object..without using obverted
vision...at Cherry Springs. I'm sure that it must be the same at NSP
too

M33 may be naked eye for some people, but for others, it is simply an
averted or "near" averted vision object. A lot of people get so used to
using averted vision that they use it without thinking and report things
as being seen directly. A year or two ago, I did some checking on my
own dark adapted absolutely "dead-on" direct vision on faint stars of
known magnitude, and with some difficulty, I got to about 5.0 (more
typically, it is around 4.8 to 4.9). With averted vision, I have gone as
faint as magnitude 7.8., although from my local dark sky site, the
limiting magnitude (averted) is often in the 6.5 to 6.8 range. M33's
total integrated magnitude is about 5.8, but this is below my limit (and
is spread over an area of nearly a square degree). I can often see M33
with the unaided eye, but not directly, and from speaking to other
observers, this is apparently a fairly common situation for many people.
I don't have to look very far away from it to see it (even from my
regular dark sky site), but if I stare absolutely directly at it, it
vanishes, no matter how good the skies are. In any case, whether
something is visible with direct vision vs. averted vision is not
necessarily a good indicator of how good the skies are. Again, this is
a flaw in the Bortle scale, as *only* the visibility (averted or direct)
of the object should have been the indicator used. Clear skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 14th Annual NEBRASKA STAR PARTY *
* July 15th-20th, 2007, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************