iPhone Screenshots


Choosing when and where to observe is hard. It's a pain to take out your telescope and then having to put it away when clouds quickly roll in.

Well, now you don't have to. With iCSC on your iPhone, you can easily search around for the best location, using Clear Sky Charts published by Attilla Danko.

The Clear Sky Chart, invented and maintained by Attilla Danko, shows at a glance when, in the next 48 hours, one might expect clear and dark skies for a specific observing site.

There are over 4600 charts available for North America, with data provided by Allan Rahill of the Canadian Meteorological Center. These charts provide Cloud Cover, Transparency, Seeing, Darkness, Wind, Humidity, and Temperature. Users can also enable a legend to help read the charts.

iCSC allows users to find charts by title, location, or with a map. Users can then save the charts that they use often.

While Clear Sky Charts are targeted at astronomers, anyone who wishes to look into the heavens, or needs a highly accurate sky forecast can benefit from iCSC: Clear Sky Chart Viewer.

What's New

Version 1.2.3

Just a small update to end the year! This update adds support for the iPhone X, improves the map, and fixes some bugs.

Please let me know if you have any issues using the in-app support form. Enjoy!

Customer Reviews

4.8 out of 5

179 Ratings

179 Ratings

Accurate and necessary


This is a wonderful tool, I use it anytime I am planning to look up at the sky.

More than just astronomy..


In addition to using this app for astronomy, I use it in my business as a professional location photographer. It is so important to me that I still have the old version and specifically held off on OS and even phone updates in fear of losing it. I have saved my clients thousands of dollars in wasted time on hiring expensive models, charter aircraft for aerials and countless other expenses related to advertising shoots because more than any other weather app out there, this app is 100% accurate in it's forecast of the sky. Now that it has been re-done, I can finally update my phone!

Great data. Layout could be better


The Clear Sky Chart is the most reliable data for stargazing. Having an app for it is great. I love the map location feature which displays the closest weather stations to your location. One complaint is that the chart seems to float on my iPhone 6 screen. It can be moved up and down and sideways. It simply just does not fit right. I think this can be improved upon. I would like the chart to fit the screen. Right now, it is too big for the screen and to see all the data, you need to move the chart around. Fix that, and you get 5 stars!


Random Widgets Inc.
18.7 MB
Requires iOS 11.0 or later. Compatible with iPhone 5s, iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, iPhone SE, iPhone 7, iPhone 7 Plus, iPhone 8, iPhone 8 Plus, iPhone X, iPad Air, iPad Air Wi-Fi + Cellular, iPad mini 2, iPad mini 2 Wi-Fi + Cellular, iPad Air 2, iPad Air 2 Wi-Fi + Cellular, iPad mini 3, iPad mini 3 Wi-Fi + Cellular, iPad mini 4, iPad mini 4 Wi-Fi + Cellular, 12.9-inch iPad Pro, 12.9-inch iPad Pro Wi-Fi + Cellular, 9.7-inch iPad Pro, 9.7-inch iPad Pro Wi-Fi + Cellular, iPad (5th generation), iPad Wi-Fi + Cellular (5th generation), 12.9-inch iPad Pro (2nd generation), 12.9-inch iPad Pro Wi‑Fi + Cellular (2nd generation), 10.5-inch iPad Pro, 10.5-inch iPad Pro Wi‑Fi + Cellular, and iPod touch.
Age Rating
Rated 4+
© 2017 Random Widgets Inc.


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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