Which major star parties have Bortle Class 1 skies?

I may have read too much into what you initially said.

Yes, I think so. I read Greg's post and did *not* infer what you did.

I think that Greg's use of the word "truly" was unfortunate, and
misled you into
thinking he was saying something that he didn't intend. His primary
point was
simply that the difference between Bortle Class 1 and Class 2 is *not*
due
to light pollution, but rather to local variations in transparency. In
other words,
a Bortle Class 1 site is simply a Bortle Class 2 site on a good night.

That sounds right to me. Many other people have said or implied the
same.
Does anybody disagree?

On your other two points, David, I think it's possible to take some
action.
Your claims a

1. The Bortle scale has too many levels.
2. The criteria within a scale are inconsistent.

The first point, I think, is partly a matter of taste and partly a
matter of
experience. It's very hard to criticize the Bortle scale on those
grounds
unless you've *habitually* observed at each of the levels, and
concluded,
in essence, "oh, the difference between level x and x+1 isn't really
important." And frankly, I don't think that *anybody* has ever
observed
consistently and habitually at all the different levels of light
pollution.
Why would they? Nobody goes out of his or her way to observe in
light pollution *worse* than what they've got at their own homes.

On the second point, I heartily agree. For instance, the business
about telescopes being invisible is just plain wrong. Yes, that
can easily happen in the eastern U.S., where people observe
in clearings in the forest, and you see the scopes with dark trees
in the background. But in the desert, the light of the Milky Way
is ample to highlight telescopes and people against the brightly
lit ground. Likewise, I'm quite sure that I'll never see M33
naked-eye no matter where I go.

But the fact is, it's very easy to criticize the Bortle Scale. But
when
you actually try to substitute a different one, you start to realize
just how much hard work went into it, and how hard it is to do
better. And since it is, for better or worse, widely used, I'd like
to propose that instead of throwing it away, we attempt to
preserve the categories but improve on the way they are
defined. That's something that I don't think any single person
can do, for the reasons I've stated above. But it does seem
possible as a collective enterprise. Among the entire internet
amateur-astro community, we have the knowledge and ability
to come up with a really consistent scale.

- Tony Flanders

wrote:

On the second point, I heartily agree. For instance, the business
about telescopes being invisible is just plain wrong. Yes, that
can easily happen in the eastern U.S., where people observe
in clearings in the forest, and you see the scopes with dark trees
in the background.



Actually what I try and do is find a small spot/clearing
in a small hollow and setup in a little *dark spot*
With the rolling countryside of Virginia it is easy
to do. And these little hollows can get soo dark, no
you cant see your hand in front of your face, or the scope.
There are times when I will sacrifice a lot of horizon
do get a nice dark spot, but even in a light polluted area
this can mean seeing a mag fainter DSO's, and or more low
SB objects. And in light polluted areas, zenith can be all
that is worthwhile anyway.....

But I agree, I cant see how on an open plain, with full
Milky Way visable how scopes could be invisible.



--


AM

On Sep 18, 8:45 am, wrote:

Are there any Class 1 sites in the east?

As an observer in the northwestern U.S. I don't know; but as others
have mentioned a Bortle-Class 1 site is *very* unlikely to *always* be
a Class-1 site. Such ideal conditions can be *very* easily destroyed
by minor variations (which can and do occur) in sky conditions.

Looking out west, my view of the light pollution data suggests that
the TSP, Oregon star party and Nebraska star party are the best bets
for Bortle class 1 skies.

It's not very difficult to find starparties (and observing sites) west
of Nebraska that have low-number, Bortle-Class skies.

Another consideration for me is the length of the star party. The
Oregon star party seems too short to bother going all the way out
there. Mt Kobou (sp?) in Canada is a longer star party but my look at
the light pollution data suggests it may only be Class 2.

An aurora, smoke from distant (or near) wild fires, a night of
brighter than average natural sky-glow, etc. can each raise a site's
Bortle-Class a few notches. Even the observer's exposure to sunlight
on the previous day can have a noticeable effect on the eye's Bortle-
Class judgement.

As for starparty durations. It's not all that uncommon in the western
U.S. to allow observers to come earlier and stay later than the
official starparty dates. Check with the organizers of any interested
starparty.

Any star parties I'm missing that are at least 5 days or so to make it
worth my while? I'd really like to try Texas but hate the idea of it
being in June this year.

The Montana StarWatch can be good; but like many other starparties,
area fires (which resulted in the cancellation of the 2007 MT
StarWatch), etc. can easily make the sky much worse than one might
have anticipated. There are no gaurantees when it comes to *any*
site's sky darkness!!

As for the Bortle scale itself, I'm in agreement with most that has
been said about it here. It can be difficult to draw a line between
Class-1 and Class-2, Class-2 and Class-3, etc.

For the sky right outside my front and back doors, a "good" night
might be anywhere between Class-3 and Class-1. Zodiacal Light, by its
very nature, is more prominent on some nights than it is on others. I
saw and carefully recorded (sketched) the Gegenschein from by front
yard last year. Part of the Zodiacal Band was visible as a narrow
extension extending eastward from the large, faint Gegenschein. A
similar extension was not seen west of the Gegenschein. Yet, when I
record my naked-eye limiting magnitude it's nearly always within a
tenth of a magnitude of 6.5. Visual acuity has a very noticeable
effect on my own NELM -- and I'm over-due for an eye-exam and new
glasses . . .

On a personal level, I would rate a Class-3 to Class-1 night to be a
good night. Class-4 conditions can often be enough to deter me from
engaging in any deepsky work from my location.

Bill Greer
To sketch is to see.
http://cejour.blogspot.com
http://www.rangeweb.net/~sketcher

wrote:

On a personal level, I would rate a Class-3 to Class-1 night to be a
good night. Class-4 conditions can often be enough to deter me from
engaging in any deepsky work from my location.


Hi, there, and thanks for a comment that illustrates an important point:
whatever scale we use to rate sky darkness and transparency, people's
customary environments and experiences are going to vary radically.
Getting urban light pollution in hand might somewhat reduce, but not
eliminate, these striking contrasts.

Thus to me, accustomed to Bortle Class 9 (around NELM 3.5), and guessing
whether I just might see NGC 253 with a broadband LPR filter, Class-4
conditions seem utopian -- the Milky Way "impressive" to the naked eye,
and NELM around 6.1-6.5. Give me that one night a week, preferably a
clear one when the Moon will be close to new or absent from the sky
during the relevant observation period, and I'll have no complaints!

However, this is also an opportunity to exercise a bit of imaginative
empathy, and try putting myself in the position of an expert observer
and sketcher for whom Class-4 conditions might mean fewer faint galaxies
or globulars, say, seen at all; and less detail teased out of visible
ones, even with prolonged observation. I ask myself, "How would you like
it if conditions got so bad that you could no longer see M22?" Would this
be like how it feels for an expert observer when conditions shift from
the Class 1-3 range to Class 4?

This discussion raises an interesting question: how utopian would it be
to set a goal of getting an urban area with about a million people
(for me, Sacramento, California, USA) to around Bortle Class 4 or 5?
Of course, if this happened, it would mean that _everyone_ could have
a reasonably nice view of the Milky Way, and also that present dark
sky sites might more often offer Bortle Class 1-3 conditions.

Is this thread maybe an invitation to solidarity between people observing
under different Bortle Class conditions: urban observers advocating for
pristine dark sky sites, and dark-sky observers advocating for better
urban conditions?

Most appreciatively,

Margo Schulter

Lat. 38.566 Long. -121.430

Margo Schulter wrote:

snip

This discussion raises an interesting question: how utopian would it be
to set a goal of getting an urban area with about a million people
(for me, Sacramento, California, USA) to around Bortle Class 4 or 5?
Of course, if this happened, it would mean that _everyone_ could have
a reasonably nice view of the Milky Way, and also that present dark
sky sites might more often offer Bortle Class 1-3 conditions.

Is this thread maybe an invitation to solidarity between people observing
under different Bortle Class conditions: urban observers advocating for
pristine dark sky sites, and dark-sky observers advocating for better
urban conditions?

This is a job for IDA! (Or somebody who *can* make a difference.)
There are so many selfish reasons for people to decrease their light
pollution:
Lower electricity bills
Lower lighting installation and maintenance costs
Lower local pollution from power generation.
Lower taxes (thinking of excess illumination of streets and public
buildings)
Safer driving environment by eliminating glare with proper shielding of
street lights.
Security issues can, to a great extent, be addressed by motion sensing
fixtures and well engineered lighting design.

None of the above address less selfish but still very compelling
benefits of decreasing light pollution:
Decreased CO2 emissions
National energy independence (in the US anyway)
Terrorism funded by the rat *******s we buy oil from
Mountain top removal coal mining
Water contamination from coal bed methane extraction
etc.


All of these reasons seem compelling enough to make a dent in light
pollution. My cynical assumption is that the energy industry is
stifling reform, no data though.
Anyone know why we're still so thick?


Shawn
Under Class 11 Clouds at the moment (6 on a good night).

writes:

Yet, when I record my naked-eye limiting magnitude it's nearly
always within a tenth of a magnitude of 6.5.

Pardon changing subject, but I am interested in how to determine
naked-eye limiting magnitude. Should I choose stars near zenit?
Should I use direct vision or averted?

Although not a newbie (I started out in the early 70's and have been
active from the early 90's), I haven't paid much attention to estimate
sky quality or darkness this far. However, I don't think I have ever
seen the velvet black sky that some observers describe. My sky is
definitely _gray_, as compared to the dark silhouettes of the wood,
and I am growing curious about how my observing spot compares to other
amateurs'. I live on the countryside in a sparsely populated area in
southern Norway (local community of 1864), with two smaller towns
(population ~6000 each) some 30 - 40 km away. I have never actually
seen M33 naked eye (I'll make another try) or the zodiacal light, and
find the Bortle scale difficult to apply.

pej
--
Per Erik Jorde

On Sep 24, 6:13 am, Per Erik Jorde wrote:

Pardon changing subject, but I am interested in how to determine
naked-eye limiting magnitude. Should I choose stars near zenit?
Should I use direct vision or averted?

By convention, naked-eye limiting magnitude is measured at the zenith
(unless stated otherwise), and uses averted vision. But NELM has very
little value as a way of comparing your skies to someone else's,
because there's a variation of at least one full magnitude, and maybe
more, in NELM estimates from different individuals under the same
skies.

However, I don't think I have ever
seen the velvet black sky that some observers describe.

That's because no such thing exists. "Velvet black sky" is a term
usually employed by people who are used to severe light pollution. In
fact, skies devoid of artificial light pollution are quite bright.

I live on the countryside in a sparsely populated area in
southern Norway (local community of 1864), with two smaller towns
(population ~6000 each) some 30 - 40 km away.

You might try to locate yourself on the Light Pollution Atlas at
http://www.lightpollution.it/worldatlas/pages/fig4.htm

I have never actually seen M33 naked eye

It's worth a another try! I can see it at sites with obvious light
pollution. But it's mighty subtle.

or the zodiacal light.

Well, there we run into one of the fundamental problems with the
Bortle Scale. The visibility of the zodiacal light depends heavily on
your latitude. It must be very hard indeed from Norway. Though it's
also worth pointing out that the zodiacal light is one of those things
that seems very difficult and exotic until the first time you've seen
and identified it. After that, it doesn't seem so hard after all.

Many of the Milky Way features cited by Bortle are also heavily
latitude-dependent. For instance, the bulge into Ophiuchus is a real
test of dark skies here at 42N, and must be extremely hard at 60N. But
the first time I saw it clearly, in southern Arizona, it seemed quite
bold and bright. And from the Southern Hemisphere, where it's nearly
overhead, it probably shines through fairly heavy light pollution.

wrote:
On Sep 24, 6:13 am, Per Erik Jorde wrote:

Pardon changing subject, but I am interested in how to determine
naked-eye limiting magnitude. Should I choose stars near zenit?
Should I use direct vision or averted?

By convention, naked-eye limiting magnitude is measured at the zenith
(unless stated otherwise), and uses averted vision. But NELM has very
little value as a way of comparing your skies to someone else's,
because there's a variation of at least one full magnitude, and maybe
more, in NELM estimates from different individuals under the same
skies.

Quite true. But it is rather useful when a specific observer is
comparing different sites. The problem comes about because the results
of different observers vary greatly. It seems that everyone's eyes are
different in terms of sensitivity, acuity and perhaps even spectral
response. But it seems a valid way to compare skies as long as it is
the same observer and done in a consistent way.

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

On Sep 24, 11:16 am, Greg Crinklaw
wrote:

NELM seems a valid way to compare skies as long as it is
the same observer and done in a consistent way.

Agreed -- with a couple of caveats.

First of all, I find that determining NELM to a high accuracy is very
tedious and time-consuming -- it takes me a minimum of a half hour,
and even then I wouldn't give it better than +-.2 mag reliability. So
in practice, I usually make do with a casual, non-numeric assessment.

Second, like Bill Greer, my NELM tops out in skies that are clearly
less than ideal, and simply doesn't get any better no matter how dark
or transparent the sky is. I've been to many places where I could see
some stars fainter than mag 6.5, but I've never been anywhere where
I've seen every mag-7.0 star that I've looked for.

So while I find NELM quite useful for a quick assessment of light-
polluted sites -- or for assessing transparency at a pretty-good site
-- I find it useless for distinguishing good skies from great skies.
For that purpose, I find the best criterion is the visibility of naked-
eye dark nebulae in the Milky Way. Unfortunately, there's no easy way
to make that quantitative!

wrote:
So while I find NELM quite useful for a quick assessment of light-
polluted sites -- or for assessing transparency at a pretty-good site
-- I find it useless for distinguishing good skies from great skies.
For that purpose, I find the best criterion is the visibility of naked-
eye dark nebulae in the Milky Way. Unfortunately, there's no easy way
to make that quantitative!

Yeah. It's basically the same problem that the Bortle scale runs into.
These things are good for determining your level of light pollution,
but begin to fail when the light pollution is dominated by differences
in transparency. Once the light pollution is basically gone, contrast
becomes the primary issue and contrast is a very difficult thing to
quantify.

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