Clear Sky Chart
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Contents
Find a chartNews (Feb 29)
Meet the Perps
Coverage Map
Your own chart
URLs & Server Status
Silly Files (Jan 5)
Boring Admin Stuff
-Terms of Use
-Copyright
-Privacy
-Advertising
Credits
How to Help
Contacts
Related Sites
| Astronomical Seeing Observations |
| Clear Sky Alarm Clock |
| Astronomy Weather email list |
The Clear Sky Chart Home page
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What is it?
It's the astronomers forecast. It shows at a glance when, in the next 48 hours, we might expect clear and dark skies for one specific observing site. There are many, but the example above is for Cherry Springs State Park, Pennsylvania.It's is specifically intended for amateur astronomers. The forecast data comes from a numerical weather model run by those very cool guys at the Canadian Meteorological Centre.
Read from left to right. Locate a column of blue blocks. That's when the sky will likely to be clear and dark. A more detailed explanation is here, which also links CMC's original forecast maps.
If you find this image, or the underlying forecast maps, useful please email Allan Rahill. He needs to show his bosses at CMC that his astronomy forecasts are actually being used. Feel free to copy me.
Are there Charts for other locations?
Yes, hundreds. The coverage area is Canada, USA and parts of Mexico.
May I get my own Chart?
If you observe at a site more than 24km or 15 miles from and existing chart site, feel free to request a chart for it. You can find the closest chart site to a latitude/longitude here.
I can generate charts for almost anywhere in Canada and US. See the coverage map. (If your're outside the coverage map, try 7Timers, an alternative astronomy weather forecast.)
Email me with:
- Latitude and longitude accurate to at least 0.01 degree or 1 arcminute. Elevation, if you know it, accurate to
the nearest 300 meters or thousand feet. If it's well known place name, like "Toronto",
then I can look up the coordinates.
For towns, use heavens-above.com. For other sites, it's best to use topo maps. But beware that a number of websites, including Mapblast, have reported positions in error of up to 35 miles. For the USA, the US Census Tiger system and topozone are good sources. For Canada, use Natural Resources Canada toporama. - Timezone and whether you use daylight savings time during summer.
- Province or State, so I can list it correctly in the directories.
- Name, or what you'd like to see in the title. Like "Starhill Observatory" or "Saskatoon". Please choose the name of a place. But star party names are good too.
- URL of a web page related to the site, if you have one. Club or observatory web pages, or web pages about public places at the location of the chart are welcome.
- Check the privacy policy and let me know if you'd like to keep confidential your site's precise location.
I reserve the right to offer you a different chart that is still close enough to give maximally accurate forecasts.
There is no cost. But it might take me a few days to respond to your request. Longer if i'm at a starparty. :)
How do I get a Clear Sky Chart to appear on my web page?
Goto the legend page for the Chart you want. Each legend page has sample html for that particular chart near the bottom of the page.| Danko's Homepage | Ottawa Astronomy Weather |