iCSC: Clear Sky Chart Viewer 4+

Astronomy forecasts for all

Random Widgets LLC

Designed for iPhone

    • 4.9 • 1.4K Ratings
    • Free

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 1.2.5

This app has been updated by Apple to display the Apple Watch app icon.

Sorry - we let a bug slip through! The issue with favorites has been fixed.

Ratings and Reviews

4.9 out of 5
1.4K Ratings

1.4K Ratings

YeahItsCollin ,

Very Accurate!

I use this for astronomy and astrophotography to help plan my time under the stars. It’s very accurate even though the closest data collection site is 20 miles away. I use this app constantly, very simple to use, and has all the information you need to consider for your Astro Endeavors.

Qborg1 ,

Excellent location conditions resource

This app gives you timely information about sky conditions for night sky observations across the United States. That said, not all observatory names tell you about their location. This is never a problem if you only plan to frequent ones that are near you and few in number, however, if you’d like to travel and plan out night sky observations along your trips the location (geographic) information is not contained in the name of each observatory. It’s kind of like someone only telling you the name of the street or city they live in. If their are multiple locations that have that street or city name, the usefulness of that information is quickly diminished. Adding GPS coordinates might help, but so would a road, city and state. If not that, then allow for notes in the favorites list on each entry so you would not need to enter the site report and then look to find it on the map. A very useful add to the app would be to make use of location information provided by cell and ip to see a list of reporting observatory’s nearby.

oaknoba ,

Can update the forecast more frequent, at least once in the afrernoon

Wondering if its possible to access the backend data source of a specific location, so I can query updated info on demand. Cloud in my area changes frequently, there are a few times the app wasn't able to catch it up until last minute and that makes the plan have to be cancelled.

App Privacy

The developer, Random Widgets LLC, indicated that the app’s privacy practices may include handling of data as described below.

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Location
  • Identifiers
  • Usage Data
  • Diagnostics

Privacy practices may vary, for example, based on the features you use or your age. Learn More

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