Clear Sky Chart
Boring Admin Stuff


Terms of Use

By using pages on this web site you agree to be a fine human being, to respect all sentient life and to not sue me. I do the best I can for users and sponsors but no contract is formed when you use my website or sponsor.

After all, it's just a weather forecast. In particular I make no statements about the safety of any site for which I provide a weather forecast. (Most of them I've never been to.) Not all clear sky chart locations are public or even physical observings sites. Check with the land owner, local astronomy clubs, or even local law enforcement for physical and safety concerns before attempting to visit sites listed

Clear Sky Charts and all the data on clear dark sky are free to use for everyone through web browsers. But authors of mobile device apps must write me for permission before using my data.

If you miss an observing event, or the 2024 solar eclipse because of an error on in weather forecasting or eclipse times or locations, your redress is limited to my apology. Eclipse watchers should check their eclipse times with the United States Naval Observatory.

Watch the 2024 Solar Eclipse at your own risk. does not provide complete eclipse saftey information. Nasa's eye safety page is a start. No joke. You may suffer partial or complete blindness if you watch the eclipse improperly. Again, by using website, you agree not to sue me.

I get to change the terms of use, or any policy without telling anyone first.

All clear sky charts belong to me, Attilla Danko, even if I use casual phrases like "your chart". They're mine. Mine I say! ...all MINE!..BWAA HA HA HA........

I reserve the right to delete charts that I believe have fallen into disuse. For the moment, that means charts whose legend pages haven't been used in 30 days.

If you sponsor the clear sky charts, I will hold you in highest esteem and thank you by listing you on my webpages for some length of time, but no contract is formed for service.

Linking and Hotlinking

Websites which do not charge admission may link any page at (Websites which do charge admission can do what they like if they first buy me a 100 acre plot under a mag 7.4 sky.)

Websites which don't charge admission, and also don't make revnue from advertising, may display chart images, or preview images, provided each image links my legend page for that chart. Use the sample html that I have provided at the bottom of each chart's legend page. (Again, tedious rules like these may be discarded in exchange for sufficent largesse.)

Do not copy text, source-html or scripts from any page unless you get written permission from me. (Mostly because it just wont work off off my webhost.)


All pages on plus all clear sky chart images and preview images, no matter what website they appear on, are Copyright 2002 - 2021 Attilla Danko.

Any transparency, cloud or seeing forecast map, labeled "CMC" is provided by the Canadian Meteorological Center and is Crown copyright, product of Environment Canada. Seek their permission to display any of their weather maps, even if the maps are sourced from

All light pollution maps are from the Light Pollution Atlas 2016 by David Lorenz. David recalculated the The World Atlas of the Artificial Night Sky Brightness with newer data. Contact David to re-publish his light pollution maps even if you get them from

Who's Rules?

This website is operated from Ottawa, Ontario, Canada and is governed by the laws of that jurisdiction even for clear sky charts for other locations. I have no idea how to make that sentence funny and clear and the same time.


Email addresses does not sell email addresses and does not do mass mailings. (Frankly, even the thought is very offensive.)

If you email me, I will only email you with regard to this web site or possibly personal correspondance.

I do not email sponsors to bug them for ever increasing amounts of money (unless they ask in advance). I might email sponsors once more about a previous sponsorship.

If you post an observation to the Astronomical Seeing Observation database, will not display your email address on any web page.

I may copy you on an email to a third person if that person is asking for changes to a chart that you requested.

Email Safety
I will never send you an email containing unicode characters, 100% html, javascript, active x, java or attachments of type *.scr or *.pif or incredible, urgent or secret offers. If you receive such, it's because someone is spoofing my email address and you should delete the email. If I ever do send someone an attachement, they'll be .txt files or in a zipfile.

I dont use them. But I've asked google to count page usage and show ads on non-sponsored charts. That generates google cookies. You can set your browser to reject them, if you like. I will consider your usage of as acceptance of such cookies otherwise.

Chart Site Locations
Normally the legend page states the latitude and longitude of chart site in the fine print at the bottom of the page. Also, links to satellite predictions and others may reveal the site's latitude and longitude. The road map link also shows the chart site's location.

Chart requesters of observatories who do not want their site made quite so public, for security reasons, may ask me for location privacy. I will then do my best to make sure their latitude and longitude does not appear on I also wont show distances to private charts as any less than 24km (15mi). I will turn off the road map, satellite prediction and other nifty, but potentially location-revealing, links on the chart's legend page. I will also turn off the "on click" navigation features of the light pollution and forecast maps linked to the chart's legend page.

Access logs
Scripts keep track of how frequently charts are used so I can figure out when to buy more computers. The data comes from log files which also capture IP addresses and referrer pages which are not made public. But nobody keeps track of who is looking at what.


I prefer sponsorship. Sponsors are wonderful people. But there just aren't enough of them. So I put google ads on clear sky chart pages -- but only clear sky chart pages that are not sponsored.

To SEOs:

Not interested. Go away.

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