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Astropheric vs. Clear Dark Sky

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#1 dcm_guitar

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Posted 20 September 2021 - 11:55 AM

I use both of these for planning sessions.  They're generally in agreement, but not always.  For example, Clear Dark Sky says tonight will be a great night to image:

 

  • No clouds all night
  • No ECMF clouds all night 
  • Transparent all night
  • Good seeing after 10:00pm, continuing to sunrise
  • No smoke
  • No wind

 

Astropheric has a different view:

 

  • No clouds all night
  • Average Transparency at 9:00pm continually getting worse until it is Poor Transparency at 3:00am
  • Seeing is Above Average after 10:00pm continuing until sunrise.
  • No wind

 

I find it interesting that one forecast says transparency is going to be really good and one forecast says "don't even bother trying to image".

 

Have you found similar situations?


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#2 ChiTownXring

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Posted 20 September 2021 - 12:04 PM

I run into this once in a great while when I look at Clearoutside vs Cleardarksky.. In the end since I image from my deck I just need one of them to tell me that it's okay to image and so I setup and then just check the doppler radar and finally step outside to look at the skies and look in the direction the clouds are coming from and go from there. 



#3 matt_astro_tx

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Posted 20 September 2021 - 12:05 PM

All.  The.  Time.

 

I use both to basically see what my week looks like for planning purposes; what nights I might stay up late, etc.

 

I also use meteoblue's seeing forecast: https://www.meteoblu...america_4684888

 

Between the three of these I can get a fairly mediocre picture of at least whether there will be clouds or not.  lol.gif

 

There's still no substitute for going outside and looking up.


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#4 OldManSky

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Posted 20 September 2021 - 12:15 PM

You do understand that all of these are statistical projections (i.e. "data-based guesses"), based on differing models, right?

So what the results are vary by what the model inputs are (and they're not all the same), and how those inputs are processed...

Historically I've found ClearDarkSky to be pretty accurate for my region.  Not always spot-on, but pretty good.  Sometimes it's really, really wrong.  That's rare...but not surprising :)


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#5 TelescopeGreg

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Posted 20 September 2021 - 01:10 PM

This may have changed, but at one point within the past year I believe Astrospheric included forecasts on smoke, where ClearDarkSky did not.  Out here in the smokey west, that's been a huge factor in my ability to image.


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#6 nyairman

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Posted 20 September 2021 - 01:16 PM

I use Astropheric for a quick smoke map. Cleardarksky is useless for my area.

My goto is always NOAA's forecasts and maps. They are the best for accuracy and realtime mapping IMHO.

#7 hornjs

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Posted 20 September 2021 - 01:22 PM

If only Clear dark sky was correct.  I always look at both.  Astrospheric is always worse (usually in transparency) and unfortunately for me is always the more accurate of the two.  CDS gets the smoke correct and there is a linkable smoke map, but usually not reflected in the transparency row.  


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#8 SarverSkyGuy

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Posted 20 September 2021 - 01:28 PM

In western Pa. I find that predicted 'above average' seeing conditions don't generally materialize.  Clarity/cloudiness seems pretty accurate.



#9 james7ca

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Posted 20 September 2021 - 03:04 PM

I've learned over the years to not really pay any attention to the forecasts unless from my own experience I can actually see a known weather pattern developing. The best way to determine cloud cover is too look and see what is actually coming your way and the best source for that is the Nighttime (NT) Microphysics Satellite imagery at a site like the following:

 

  https://weather.cod....orbar=undefined

 

Here you can see nighttime satellite imagery in an animation loop that will show low clouds, high clouds, fog, or just about anything in between. Highly recommended.

 

As for seeing forecasts, those can often be in error and if you're going strictly by those types of forecasts you are likely going to miss a good number of opportunities for superior results. Plus, seeing can be very local, so again you have to know your own weather patterns and the specific circumstances of your location.


Edited by james7ca, 20 September 2021 - 03:07 PM.

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#10 lphilpot

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Posted 21 September 2021 - 09:18 AM

I have to give credit to Astrospheric recently. This year, it's consistently said skies will be crappy and they've been crappy. All. Year. So. Far. Then again, maybe that's not much of a limb to go out on, all things considered...  confused1.gif


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#11 unimatrix0

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Posted 21 September 2021 - 09:44 AM

Cleardarksky is usually over- optimistic to be good at my location, why clearoutside rather tells me worse conditions than it ends up to be.  From my experience, if there are clouds anywhere in the 100 mile radius, there is a 50/50 chance to go either way.  If the clouds passing in a 50 mile radius anywhere near me, just forget about imaging.  The weather is very unpredictable all year long.  This whole summer was a waste of time - as far as trying to produce a really good image, but a good learning experience with the number of clear skies I can count on 1 hand since April. 


Edited by unimatrix0, 21 September 2021 - 09:45 AM.


#12 dx_ron

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Posted 21 September 2021 - 09:57 AM

How I use these sites depends on if I am trying to plan a couple of days ahead vs making a decision about tonight. Both Astrospheric and cleardarksky show you the simulated satellite view based on their model (you have to click on a specific hour at cleardarksky to be taken to that view). At the simplest level, the smaller and more broken is a 1- or 2-day ahead projected cloud bank, the less likely it is to be telling you much useful. Projected clouds covering a large area are probably going to be there, unless the atmosphere does something the models did not account for. Smaller cloud banks could easily go somewhere a hundred miles away from where the model says without it being a surprise at all.

 

On the day of, you have actual sat images to compare to the projections, Usually the cloud projections are a few hours old when you look at them - do they bear much resemblance to current real clouds?

 

The final go/no-go decision is still up to the real current conditions, but trying to decide to drive an hour or make plans that prevent setting up at home means trying to predict the future.


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#13 moab360

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Posted 28 September 2021 - 12:01 AM

I use both of these for planning sessions.  They're generally in agreement, but not always.  For example, Clear Dark Sky says tonight will be a great night to image:

 

  • No clouds all night
  • No ECMF clouds all night 
  • Transparent all night
  • Good seeing after 10:00pm, continuing to sunrise
  • No smoke
  • No wind

 

Astropheric has a different view:

 

  • No clouds all night
  • Average Transparency at 9:00pm continually getting worse until it is Poor Transparency at 3:00am
  • Seeing is Above Average after 10:00pm continuing until sunrise.
  • No wind

 

I find it interesting that one forecast says transparency is going to be really good and one forecast says "don't even bother trying to image".

 

Have you found similar situations?

 

Hi there, as the creator of Astrospheric, I've got (some) answers!

 

The primary forecast model used by Astrospheric and Clear Dark Sky is the same (RDPS model produced by Canadian Meteorological Center (CMC)) so many think they'll produce the same result.  There are some major differences though that generally give Astrospheric the leg up.  For transparency specifically, point # 3 below probably explains it.

  1. Astrospheric process raw model data directly from the CMCs supercomputers. This is why Astrospheric updates 4 times a day instead of twice like Clear Sky Chart. Processing the raw data also allows Astrospheric to produce high quality map overlays to visualize the data.  We've worked with the fine folks at the CMC to make more data available this way.
  2. Astrospheric dynamically generates a forecast for the exact location you choose instead of working off a predefined set of locations. Even with thousands of locations available on Clear Sky Chart, that only represents a tiny fraction of the CMCs forecast data. By generating the forecast dynamically, Astrospheric can take advantage of the high resolution CMC data and get you the best results.
  3. Astrospheric is upgrading its astronomy variables to better reflect current conditions with the help of scientists at the CMC and NOAA. For example, Astrospheric’s Transparency forecast integrates the latest smoke and aerosol data to produce a more realistic forecast of sky transparency. Seeing is computed for each hour instead of 3 hour blocks.  Astrospheric's cloud forecast looks at trends in cloud movement in the area to produce a more accurate forecast.
  4. There are many other functional differences between the services. Clear Sky Chart is obviously still a valuable resource and some users may prefer it given Astrospheric's higher system / bandwidth requirements.

 

Here is another Cloudy Night post I created on an identical question of why the transparency was worse - https://www.cloudyni...-is-in-the-air/

 

Anyways, let me know if there are other q's, happy to answer questions and always love getting feedback

 

Clear Skies!


Edited by moab360, 28 September 2021 - 12:02 AM.

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