Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
Get a Cloudy Nights T-Shirt Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu uh, User

General Astronomy >> General Observing and Astronomy

Pages: 1 | 2 | (show all)
mak17
scholastic sledgehammer
*****

Reged: 02/08/11

Loc: Central Florida
Bortle 3 vs Bortle 2 new
      #6089980 - 09/19/13 01:28 PM

Ive never been to a site darker then bortle 3. One night at the WSP at about 4am after waking from a nap i thought it looked darker then normal blue zone skies im used to. Anyway is going from a blue zone with limiting magnitude of 6.9 to a bortle 2 worth the extra time and expense of adding a couple hours more driving into my trip this upcomng new moon weekend? Curious to hear from people who observe in grey zones and blue zones on the significance of improvement of views at the eyepiece between these two zones. Im really excited about potential grey zone trip but am afraid it may not be a noticeable difference. Ill still go if weather permits but would like to hear from experience what to expect. Thanks.

Chris


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark9473
Postmaster
*****

Reged: 07/21/05

Loc: 51N 4E
Re: Bortle 3 vs Bortle 2 new [Re: mak17]
      #6090054 - 09/19/13 02:13 PM

To me it wouldn't be worth it; Bortle 3 is already 4 steps above my backyard.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Starman81
Carpal Tunnel
*****

Reged: 03/06/08

Loc: Metro Detroit, MI, USA
Re: Bortle 3 vs Bortle 2 new [Re: Mark9473]
      #6090103 - 09/19/13 02:45 PM

I would love to go to a blue zone, but wouldn't drive 2 extra hours for a gray. From what I recall reading in a different thread, the difference between Bortle 1-3 is only noticeable from 30* on down. Above 30*, the three are the same--very dark. Also, my guess is that a really good blue site in the wee hours of the night as you described, when the air is still and human activity is low (meaning more lights are off), it could be improve to meet the criteria of a gray zone (I think!). Best way to tell is to have an SQM on hand and measure darkness throughout the night.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Seldom
scholastic sledgehammer


Reged: 08/05/12

Loc: N of Cedar City Light Dome
Re: Bortle 3 vs Bortle 2 new [Re: Starman81]
      #6090207 - 09/19/13 03:58 PM

Quote:

I would love to go to a blue zone, but wouldn't drive 2 extra hours for a gray. From what I recall reading in a different thread, the difference between Bortle 1-3 is only noticeable from 30* on down. Above 30*, the three are the same--very dark.




Can you elaborate on what 30 degrees latitude has to do with it?

FWIW, my back yard is shown as light blue on the 16 color DarkSiteFinder map. Great Basin is shown as dark gray. My SQM-L readings for my yard are 21.5 MPSAS. The readings I took the other week on the only clear night of the Great Basin Star Party were also 21.5 MPSAS. My SQM-L readings in a dark closet are well over 23 MPSAS, so I don't think the meter was topping out in my back yard, but it does make me wonder about the meaning of blue, gray and dark gray zones, or the reliability of Sky Quality Meters.

Also FWIW, at Great Basin, I tried for, but couldn't see M33 with averted vision. This makes me suspicious of NELM listings, because they are all dependent on the quality of our individual eyes. As we get older, our lenses get cloudy, so an old guy's NELM isn't the same as a whippersnappers.

Edited by Seldom (09/19/13 04:10 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
hbanich
Pooh-Bah
*****

Reged: 06/17/05

Loc: Portland, Oregon
Re: Bortle 3 vs Bortle 2 new [Re: Seldom]
      #6090244 - 09/19/13 04:19 PM

Quote:


FWIW, my back yard is shown as light blue on the 16 color DarkSiteFinder map. Great Basin is shown as dark gray. My SQM-L readings for my yard are 21.5 MPSAS. The readings I took the other week on the only clear night of the Great Basin Star Party were also 21.5 MPSAS. My SQM-L readings in a dark closet are well over 23 MPSAS, so I don't think the meter was topping out in my back yard, but it does make me wonder about the meaning of blue, gray and dark gray zones, or the reliability of Sky Quality Meters.

Also FWIW, at Great Basin, I tried for, but couldn't see M33 with averted vision. This makes me suspicious of NELM listings, because they are all dependent on the quality of our individual eyes. As we get older, our lenses get cloudy, so an old guy's NELM isn't the same as a whippersnappers.




It's good to remember that the color zones for light pollution are only a rough guide, not an absolute indication of what every clear night will be like. Transparency, air pollution, aerosols, smoke, air glow and low-grade aurora make a huge difference night to night on how dark the sky will look and measure on an SQM. So there's no way to say that driving two more hours to an observing site will pay off with darker skies and better observing without having a good weather and space weather forecast a day or two in advance.


Post Extras: Print Post   Remind Me!   Notify Moderator  
rockethead26
Post Laureate
*****

Reged: 10/21/09

Loc: Arizona, USA
Re: Bortle 3 vs Bortle 2 new [Re: Seldom]
      #6090277 - 09/19/13 04:41 PM

Quote:

Quote:

I would love to go to a blue zone, but wouldn't drive 2 extra hours for a gray. From what I recall reading in a different thread, the difference between Bortle 1-3 is only noticeable from 30* on down. Above 30*, the three are the same--very dark.




Can you elaborate on what 30 degrees latitude has to do with it?






He's referring to 30 above the horizon, below which most light domes occur.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Starman81
Carpal Tunnel
*****

Reged: 03/06/08

Loc: Metro Detroit, MI, USA
Re: Bortle 3 vs Bortle 2 new [Re: rockethead26]
      #6090291 - 09/19/13 04:48 PM

Quote:

Quote:

Quote:

I would love to go to a blue zone, but wouldn't drive 2 extra hours for a gray. From what I recall reading in a different thread, the difference between Bortle 1-3 is only noticeable from 30* on down. Above 30*, the three are the same--very dark.




Can you elaborate on what 30 degrees latitude has to do with it?






He's referring to 30 above the horizon, below which most light domes occur.




Yes, that is correct, I was referring to the horizon. The thread I was referring to is here and I guess it was only one comment, but no one refuted it and it certainly sounds plausible.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Seldom
scholastic sledgehammer


Reged: 08/05/12

Loc: N of Cedar City Light Dome
Re: Bortle 3 vs Bortle 2 new [Re: rockethead26]
      #6090294 - 09/19/13 04:49 PM

Quote:


He's referring to 30 above the horizon, below which most light domes occur.




Post Extras: Print Post   Remind Me!   Notify Moderator  
Seldom
scholastic sledgehammer


Reged: 08/05/12

Loc: N of Cedar City Light Dome
Re: Bortle 3 vs Bortle 2 new [Re: hbanich]
      #6090328 - 09/19/13 05:08 PM

Quote:


Transparency, air pollution, aerosols, smoke, air glow and low-grade aurora make a huge difference night to night on how dark the sky will look and measure on an SQM.




I've noticed varying levels of air glow on fairly transparent nights, but never to my knowledge have seen a "low grade aurora". At Lat 38 should I be looking for them?

Also, I just bookmarked the NOAA space weather page. Should I just be looking at the "Auroral Activity" link? If so, it looks like the low level activity doesn't get much below Lat 42.


Post Extras: Print Post   Remind Me!   Notify Moderator  
BrooksObs
professor emeritus


Reged: 12/08/12

Re: Bortle 3 vs Bortle 2 new [Re: Seldom]
      #6090751 - 09/19/13 10:16 PM

Starman - The statement made from the post you cite is, I'm afraid, decidedly off the mark with regard to accuracy when it is indicated that:

"Areas designated blue, grey or black are almost identical in appearance from 30 above the horizon to the zenith, in my experience. If fortunate enough to be observing from a clearing which is surrounded by tall, dense trees, which thoroughly block out any light domes that may be present on the horizon, one would be hard-pressed to discern much, if any, difference between these areas with one's eyesight alone."

The presence of light domes along the horizon impact the darkness of the entire sky to at least some degree, so simply blocking them out, together with hiding the lower 30* of sky, will not negate the differences between Bortle Classes 3, 2 and 1.

I would add that it is very unlikely that more than perhaps a handful of folks here have ever actually experience Bortle Class 1 skies. Believe me, if you ever have that opportunity, you'll have no doubt that decided differences exist between Bortle classes at the very lowest end of the scale.

Addressing the OP's question, the actual worth of driving considerably farther out from civilization to gain one or maybe two additional levels of darkness will depend critically on the nature of the observation you are attempting to make and perhaps the ultimate value that it may have to you and to others, at least in my book.

BrooksObs

Edited by BrooksObs (09/19/13 10:18 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
hbanich
Pooh-Bah
*****

Reged: 06/17/05

Loc: Portland, Oregon
Re: Bortle 3 vs Bortle 2 [Re: Seldom]
      #6090927 - 09/20/13 12:28 AM

Quote:

Quote:


Transparency, air pollution, aerosols, smoke, air glow and low-grade aurora make a huge difference night to night on how dark the sky will look and measure on an SQM.




I've noticed varying levels of air glow on fairly transparent nights, but never to my knowledge have seen a "low grade aurora". At Lat 38 should I be looking for them?

Also, I just bookmarked the NOAA space weather page. Should I just be looking at the "Auroral Activity" link? If so, it looks like the low level activity doesn't get much below Lat 42.




Auroral glow can certainly effect the sky at your latitude, but it will be weak for the most part. I check http://www.spaceweather.com/ for auroral events because even though they rarely have a noticeable impact on sky conditions here at 45 degrees north, every so often...


Post Extras: Print Post   Remind Me!   Notify Moderator  
MEE
super member


Reged: 07/10/10

Re: Bortle 3 vs Bortle 2 new [Re: hbanich]
      #6090962 - 09/20/13 01:07 AM

Is it a big gray zone area? How deep into the blue zone do you observe? If you're going deep into a large area of the gray zone, and if you normally observe from the blue zone but close to the border with the green zone, then there is a chance that the difference will be noticeable. No guarantee, though.

On the other hand, I would say that you might as well try it at least once: sure, an extra two hours might be too much on a regular basis...but why wouldn't you try it once?

As others have posted above, the color zones are only a rough guide. Be aware that the Bortle Class of a certain location can change several times during the night. From the green zone locations I normally observe from, I have experienced Class 5, Class 4, and Class 3 conditions. One exceptionally clear night, I experienced Class 2 conditions from that green zone area for a few hours!

A single visit for a few hours to a location is NOT a true way to estimate how dark the location is on a regular basis. Only multiple visits to the same location under the same general conditions (no moon, clear skies, fully dark-adapted eyes) can give you a better idea of the "average" sky darkness of that location.

You could also just make a nice mini-vacation out of it and see other things in the area and that way if the sky conditions don't work out for you, you can still say you had a good time.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Starman81
Carpal Tunnel
*****

Reged: 03/06/08

Loc: Metro Detroit, MI, USA
Re: Bortle 3 vs Bortle 2 new [Re: BrooksObs]
      #6090970 - 09/20/13 01:16 AM

I have never been to either a Bortle 1, 2 or 3 yet so I would not know. All I can do is glean wisdom from the learned elders, and when you disagree, I'll let you guys duke it out!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Special Ed
Postmaster
*****

Reged: 05/18/03

Loc: Greenbrier Co., WV 38N, 80W
Re: Bortle 3 vs Bortle 2 new [Re: BrooksObs]
      #6091124 - 09/20/13 06:00 AM

Quote:

Starman - The statement made from the post you cite is, I'm afraid, decidedly off the mark with regard to accuracy when it is indicated that:

"Areas designated blue, grey or black are almost identical in appearance from 30 above the horizon to the zenith, in my experience. If fortunate enough to be observing from a clearing which is surrounded by tall, dense trees, which thoroughly block out any light domes that may be present on the horizon, one would be hard-pressed to discern much, if any, difference between these areas with one's eyesight alone."

The presence of light domes along the horizon impact the darkness of the entire sky to at least some degree, so simply blocking them out, together with hiding the lower 30* of sky, will not negate the differences between Bortle Classes 3, 2 and 1.

I would add that it is very unlikely that more than perhaps a handful of folks here have ever actually experience Bortle Class 1 skies. Believe me, if you ever have that opportunity, you'll have no doubt that decided differences exist between Bortle classes at the very lowest end of the scale.

Addressing the OP's question, the actual worth of driving considerably farther out from civilization to gain one or maybe two additional levels of darkness will depend critically on the nature of the observation you are attempting to make and perhaps the ultimate value that it may have to you and to others, at least in my book.

BrooksObs




This person knows what he's talking about.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Illinois
Carpal Tunnel


Reged: 12/18/06

Loc: near Dixon, Illinois USA
Re: Bortle 3 vs Bortle 2 new [Re: Special Ed]
      #6091166 - 09/20/13 07:01 AM

Mak17, that's dark than most place in Illinois! Enjoy as much as you can! Orlando, Disney, Miami, Tama Bay and many town growing to gain light pollution. I know Harmony (cant remember spell) is dark sky town near St Cloud but not that dark. Green zone is good in Illinois and hope someday to improve reduce light pollution everywhere!

Post Extras: Print Post   Remind Me!   Notify Moderator  
BrooksObs
professor emeritus


Reged: 12/08/12

Re: Bortle 3 vs Bortle 2 new [Re: Illinois]
      #6091228 - 09/20/13 08:24 AM

MEE posts = "As others have posted above, the color zones are only a rough guide. Be aware that the Bortle Class of a certain location can change several times during the night. From the green zone locations I normally observe from, I have experienced Class 5, Class 4, and Class 3 conditions. One exceptionally clear night, I experienced Class 2 conditions from that green zone area for a few hours!

A single visit for a few hours to a location is NOT a true way to estimate how dark the location is on a regular basis. Only multiple visits to the same location under the same general conditions (no moon, clear skies, fully dark-adapted eyes) can give you a better idea of the "average" sky darkness of that location."


All of which is absolutely true. And it does point up that many here are addressing the Bortle scale in an incorrect manner. Its intent is more in the way of the evaluation and documenting prevailing sky conditions AT THE TIME the specific observation being reported was made, not necessarily to PREDICT what a given site experiences on a night-to-night basis. While such a use can indeed provide some indication of what can be anticipated it is no guarantee that a given night, even at an outstanding location, might not actually differ by one or even two classes depending on prevailing sky conditions.

BrooksObs

Edited by BrooksObs (09/20/13 08:28 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Startraffic
professor emeritus
*****

Reged: 02/12/06

Loc: Lat. 39.143345, Long. -77.1748...
Re: Bortle 3 vs Bortle 2 new [Re: BrooksObs]
      #6091724 - 09/20/13 12:50 PM

I don't want to hear it. I'm solidly in a WHITE zone where there is No milky way, DSO's extremely hard to find let alone image.

Clear Dark Skies
Startraffic
39.138274 -77.168898


Post Extras: Print Post   Remind Me!   Notify Moderator  
MikeRatcliff
Carpal Tunnel
*****

Reged: 06/12/04

Loc: Redlands, CA
Re: Bortle 3 vs Bortle 2 new [Re: Startraffic]
      #6091781 - 09/20/13 01:13 PM

I observe regularly in "blue" or "Bortle 3" sites in S. California, and occasionally in a grey or Bortle 2 site.
I don't personally have an SQM meter, but from hearing others, a typical night at my blue sites are 21.3 and a 21.5 to 21.6 at the grey site.

To me there is a noticeable difference. For example, scanning the Milky Way, dark nebula jump out at you compared to just being able to see them. Dust lanes in M31 are more pronounced on average. The pesky very low contrast "bright" nebula like some of the Sharpless listings are a little easier. Faint globulars are easier. Everything really looks a little better at least.

I don't go to the grey zones often because I feel more tired at work on Monday morning with the longer drives. So it is a tough call for me personally on which is better overall.

Mike


Post Extras: Print Post   Remind Me!   Notify Moderator  
mountain monk
Carpal Tunnel
*****

Reged: 11/06/09

Loc: Grand Teton National Park
Re: Bortle 3 vs Bortle 2 new [Re: Startraffic]
      #6091827 - 09/20/13 01:35 PM

From my experience, BrooksObs is correct about this. It is imperative to keep Bortle classes and color zones separate. I live in a blue zone and often observe in a gray zone. For decades I lived in a black zone. Is it worth driving two hours to go fron blue to gray. With a reasonable chance of equally good skies at both, I would say go...at least once, and see for your self. For me, it would be too far to go on a regular basis, although I will drive that for a black zone at high altitude---8000-10000 feet. All the caveats mentioned apply---skies can change in minutes. I have been in and observed under Bortle 1 skies, but I think they are pretty darn rare in North Americs. Exist but rare.

If you go, let us know what you think.

Dark skies.

Jack


Post Extras: Print Post   Remind Me!   Notify Moderator  
mak17
scholastic sledgehammer
*****

Reged: 02/08/11

Loc: Central Florida
Re: Bortle 3 vs Bortle 2 new [Re: mountain monk]
      #6091875 - 09/20/13 02:03 PM

Thanks everyone for your feedback. It is a pretty big gray zone i guess. I normally observe with a green zone bordering the blue zone to the north but blue in every other direction. We normally can only see one lightdome to the north. Hoping to see no light domes as described on the cleardarksky website description of gray zone. I usually observe DSOs hoping to see more faint details. Just cleaned my mirror in anticipation. Only two more weeks....

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | (show all)


Extra information
8 registered and 6 anonymous users are browsing this forum.

Moderator:  cildarith, panhard, tecmage 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 1224

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics