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General Astronomy >> General Observing and Astronomy

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orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Seeing Chart USA new
      #5972781 - 07/15/13 05:40 PM

Is there a chart that shows the ave seeing conditions across the USA?
I live in the Midwest and seems that I have so many bad
nights. Or are 3 or 4 good seeing nights such a 4 or 5
the norm. Seems you lucky left Coasters get all the good seeing and use it all up, before we get it!!


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krp
Vendor. DarkSiteFinder.com


Reged: 11/10/10

Loc: Central Illinois
Re: Seeing Chart USA new [Re: orion61]
      #5972830 - 07/15/13 06:14 PM

If you go to Clear Dark Sky look for a location with a red star next to it. Since those charts are sponsored they keep a history of observing conditions. It's easy to see comparing different locations that the west coast gets good seeing much more often. In Chicago for example 5/5 seeing happens on 3% of clear nights in July. In Huntington Beach, CA 5/5 seeing happens on 23% of clear nights in July.

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dc_robert
super member
*****

Reged: 04/17/13

Loc: Washington, DC
Re: Seeing Chart USA new [Re: krp]
      #5973186 - 07/15/13 09:46 PM

Maybe this site is what you're looking for?

http://www.jshine.net/astronomy/dark_sky/


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derangedhermit
Pooh-Bah


Reged: 10/07/09

Loc: USA
Re: Seeing Chart USA new [Re: krp]
      #5973628 - 07/16/13 06:41 AM

Quote:

If you go to Clear Dark Sky look for a location with a red star next to it. Since those charts are sponsored they keep a history of observing conditions. It's easy to see comparing different locations that the west coast gets good seeing much more often. In Chicago for example 5/5 seeing happens on 3% of clear nights in July. In Huntington Beach, CA 5/5 seeing happens on 23% of clear nights in July.



I've been thinking about asking Attilla what it would take to get some statistics run across the sponsored sites so he could map seeing, cloudiness, etc. across the locations over the several years of data he has.


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RedLionNJ
scholastic sledgehammer


Reged: 12/29/09

Loc: Red Lion, NJ, USA
Re: Seeing Chart USA new [Re: derangedhermit]
      #5973696 - 07/16/13 08:18 AM

I've found Clear Dark Sky to be largely off-the-mark. Perhaps I'm looking at it from a biased viewpoint, but when it predicts clear or steady from my NJ location, I always try to observe. It has never been right this year as far as good (not even excellent) seeing and there have often been clouds on evenings predicted to be clear.

I think the model is seriously flawed.

Grant


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mich_al
Carpal Tunnel
*****

Reged: 05/10/09

Loc: Rural central lower Michigan ...
Re: Seeing Chart USA new [Re: RedLionNJ]
      #5973734 - 07/16/13 09:15 AM

Quote:

I've found Clear Dark Sky to be largely off-the-mark. Perhaps I'm looking at it from a biased viewpoint, but when it predicts clear or steady from my NJ location, I always try to observe. It has never been right this year as far as good (not even excellent) seeing and there have often been clouds on evenings predicted to be clear.

I think the model is seriously flawed.

Grant





It's been pretty accurate for this location over many years. Not 100% but often when I second guess their prediction I'm the one who is wrong.


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orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Seeing Chart USA new [Re: mich_al]
      #5973821 - 07/16/13 10:21 AM

Actually I referring to areas that have consistantly better seeing than other parts of the country.
I know when I visit my friend in Colorado, the seeing is always better than here in the Midwest.
I always use the Clear Sky Chart in Storm Lake and find it
to lack for accuracy. Example in the last week it has been Cloudy once and Rained another time when it was supposed to be clear.


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Tom Polakis
Carpal Tunnel
*****

Reged: 12/20/04

Loc: Tempe, Arizona
Re: Seeing Chart USA new [Re: RedLionNJ]
      #5973862 - 07/16/13 10:41 AM

Quote:

I've found Clear Dark Sky to be largely off-the-mark. Perhaps I'm looking at it from a biased viewpoint, but when it predicts clear or steady from my NJ location, I always try to observe. It has never been right this year as far as good (not even excellent) seeing and there have often been clouds on evenings predicted to be clear.

I think the model is seriously flawed.





It's the best tool we have. I do planetary imaging from my backyard, and have found the CSC does a very good job at predicting when the seeing is going to be poor. When the seeing in my area is represented as light blue or white, it's never good. The CSC is less reliable when it predicts dark blue, good seeing. In those cases, you just have to go out and look.

Of course, this observation only represents my location in metro Phoenix. In your experience, are there ever nights with good seeing in which CSC shows that it is supposed to be poor?

One other hint regarding the CSC is to always look at the map representation, and not the little squares on the timeline. If the zone of dark blue uniformly covers a large area, seeing is likely to be good. Sometimes, the model shows a sort of mottled appearance on the map, with closely interspersed zones. Then it's anybody's guess.

Tom


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Tom and Beth
Post Laureate


Reged: 01/08/07

Loc: Tucson, AZ
Re: Seeing Chart USA new [Re: Tom Polakis]
      #5973973 - 07/16/13 11:47 AM

I also like CSC, even if it has missed from time to time. Yet before I would throw it out with the bathwater, I would compare the accuracy of CSC against the accuracy of your local weather predictions.

I'd also note that before the weather service people would have just gone outside and made semi accurate predictions.


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Michael Rapp
Post Laureate
*****

Reged: 04/27/04

Loc: Dickinson, TX
Re: Seeing Chart USA new [Re: Tom and Beth]
      #5974120 - 07/16/13 01:11 PM

Here's the chart I use. It is the 300 mb pressure chart, which basically is the steadiness of the upper atmosphere. Purple = rock steady, cyan and yellow = forget it.

If you watch this over the course of a year, you'll see why some of the best planetary images come from Florida and Texas during the summer.

http://weather.unisys.com/gfs/4panel/gfs_300_4panel1.gif


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Tony Flanders
Postmaster
*****

Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: Seeing Chart USA new [Re: orion61]
      #5974183 - 07/16/13 01:41 PM

Quote:

Actually I referring to areas that have consistantly better seeing than other parts of the country.
I know when I visit my friend in Colorado, the seeing is always better than here in the Midwest.




Just to clarify -- are you actually talking about seeing in the technical sense (steady air for high-power viewing) or about transparency (clear air) and/or cloudiness? For what it's worth Colorado is not famous for good seeing -- rather the opposite, if anything.


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csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: Seeing Chart USA new [Re: Tony Flanders]
      #5974307 - 07/16/13 02:33 PM

Yup, we get a lot of overhead Jet Stream, and unstable high atmosphere on a good day. But we do get enough good days to make it enjoyable.

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KWB
Postmaster
*****

Reged: 09/30/06

Loc: Westminster,Co Elev.5400 feet
Re: Seeing Chart USA new [Re: csrlice12]
      #5974413 - 07/16/13 03:31 PM

Colorado is a pretty big state and it depends on one's geography/topography as to a viewing location,so making a general statement about the conditions on a whole cannot be cut and dried. Eastern Colorado often has pretty good seeing conditions,and has less atmosphere to have to peer through than most of the eastern U.S. The dark skies starting 100 miles east of Denver are a bonus. IME here the Jet Stream is usually far to the north of the state during the summer. The turbulance of the air coming down off the Front Range causes the unsteady seeing we get locally,but there are still many summer nights even in metro Denver when after midnight,the sky steadies nicely to around a Pickering 7 on that scale. I experience many more good nights of viewing versus bad one's,and that opinion is based upon a lifetime of viewing in this region.

The University of Denver has what is now the second highest observatory in the world atop Mt Evans west of Denver,at 14,260 feet in elevation. If the seeing conditions were abysmal on a consistent basis,the school wouldn't have wasted their time or money building the observatory up there. No,this mountain location doesn't have the consistent steady skies that coastal California obsevatories do but even with the limited season available due to the severe climate the professor that is in charge of the facility stated to me that he gets many useable nights of observation in the summer season.

The west slope of the state has some pretty good seeing conditions as well,Grand Junction,Craig and around the 4 corners area near Cortez. These quality nights are nowhere near rare in summer.


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Happy Birthday Adam Taylor
insignificant bystander
*****

Reged: 11/11/10

Loc: Arizona
Re: Seeing Chart USA new [Re: orion61]
      #5974451 - 07/16/13 03:54 PM Attachment (13 downloads)

Why not use multiple resources for observation planning?

Below is a screenshot of some HTML I threw together to make a meteo resource page. It has:

- 3-day general forecast
- Current conditions with lunar phase
- Nearest CSC
- Last 6-hours animated IR Sat
- Next 6-hours seeing forecast
- Latest Jet Stream

Each is hyperlinked to more detail.


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RedLionNJ
scholastic sledgehammer


Reged: 12/29/09

Loc: Red Lion, NJ, USA
Re: Seeing Chart USA new [Re: Tom Polakis]
      #5975014 - 07/16/13 09:04 PM

Quote:

In your experience, are there ever nights with good seeing in which CSC shows that it is supposed to be poor?





This is precisely why I said I may be biased. I generally only view it from the other perspective. When it shows dark blue for seeing (4/5), like the early part of this evening, I get all hopeful.

Then I point my well-collimated and cooled-down scope at Saturn and UGH. A shimmering ball, not even revealing the Cassini division. I don't think CSC takes into account the thermal currents from Earth's cooling in the early evenings.

I can point straight overhead and the seeing IS pretty good (maybe 3/5), but it's certainly not 4/5 over toward Saturn.

Grant


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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Seeing Chart USA [Re: RedLionNJ]
      #5975481 - 07/17/13 06:07 AM

A few thoughts:

Seeing, that is the stability of the atmosphere depends not only the big picture, the sorts of things the Clear Sky Clock looks at, but also local conditions that affect the seeing.

Around here in the city where the local conditions are quite good, a few miles from the coast with mild breezes flowing off the water, the CSC does a good job of predicting the seeing. At our place up in the mountains, it's not so good at predicting the seeing because it's on the lee side of a mountain range and there seems to often be a lot of turbulence created by wind sheer off the ridges.

Jon


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Phillip Creed
Idiot Seeking Village
*****

Reged: 07/25/06

Loc: Canton, OH
Re: Seeing Chart USA new [Re: Jon Isaacs]
      #5976733 - 07/17/13 08:07 PM

I've found the seeing forecast on CSC to be fairly reliable, as well as the cloud cover forecasts, but it's always important to actually take a look at the generated maps for a view of the surrounding region. If you've got dark blue blocks but CSC is predicting a 20-mile wide gap in an otherwise-solid regional overcast, it's best to be suspicious. The same caution would apply to the seeing forecast as well.

The transparency forecast is the one that I've found off the mark the most. It's essentially a forecast of the amount of moisture lying between the observer and outer space. While higher moisture correlates well with reduced transparency, that's because one has to factor in the aerosol load as well. Most summertime haze in the Eastern U.S. is caused by sulfate emissions that grow to sizes that are insidiously effective at scattering light in humid, stagnant air masses. Moisture EXACERBATES haze, but it does not CAUSE haze. Water vapor is completely transparent in the visible spectrum.

Another source of aerosols is forest fire smoke. CSC doesn't factor this in at all.

Thankfully, sulfate emissions are dropping in the Eastern U.S. Only today has our transparency in Ohio started to take a minor hit, and we've had 90F temp / 70F dewpoint weather for four straight days. Even ten years ago, we'd have had a solid week of haze by now in the Buckeye State under such conditions.

Clear Skies,
Phil


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orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Seeing Chart USA new [Re: Phillip Creed]
      #5977036 - 07/17/13 11:35 PM

Sorry been gone a couple days..
My Buddy lives in CO Springs and we head up into the mountains for viewing. I will say at 10,000 ft up it's the best seeing I have experienced.. but WOW does that temp drop when the Sun goes down...
going back out.. it's one of those ex nights out there.
#@! Moon, Skeeters done swarming now.


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Mike B
Starstruck
*****

Reged: 04/06/05

Loc: shake, rattle, & roll, CA
Re: Seeing Chart USA new [Re: Phillip Creed]
      #5977167 - 07/18/13 01:36 AM

Quote:

Why not use multiple resources for observation planning?




Quote:

Seeing, that is the stability of the atmosphere depends not only the big picture, the sorts of things the Clear Sky Clock looks at, but also local conditions that affect the seeing.




Quote:

...but it's always important to actually take a look at the generated maps for a view of the surrounding region.



Yes, this can make all the difference. The CSC is merely a beginning point, or a single data-point among several, and a *macro* one at that.

Thanks for posting the above "Unisys" link! Very cool- have added that to my data bank!


Quote:

I think the model is seriously flawed.



I've found the CSC's in my region are fairly reliable, tho certainly not flawless. I'm sure this varies by location, and/or by category, as each micro-region will have localized effects that the scale of the CSC misses. Remember, it only samples various locations- these may or may not be predictive beyond any given sensor's location. The two nearest me are at mountain tops... i live in a valley between; what are the chances they'll be accurate for their locations, up there, but hit/miss for me?

Of course, many have been the times i've sold it short- and regretted it; the CSC indicated clear & gorgeous, but all i saw was clouds. I bailed... only to step outside later that eve, look up, and see.... ayup, gorgeous skies!


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