Carry your favourite Clear Sky Charts (CSC) in your pocket! Amateur astronomers in North America monitor local sky conditions using the CSC web sites which provide a very detailed 48 hour color coded observing forecast chart for cloud cover, transparency, seeing and other factors. This app contains a database of more than 6000 forecast locations in Canada, the USA and Mexico and can check for new updates. The launch screen monitors up to four or five favourite observing locations. Each square represents one hour and the colors vary from dark blue (excellent) to white (very poor) conditions for observing. A red line indicates local midnight and there is a last updated timestamp. Tapping on any preview chart will open a menu of options that allows you to (i) see a more detailed chart with legend, (ii) map the chart location, (iii) open the CSC web page, (iv) select a different chart location to monitor, (v) remove unwanted charts or (vi) share one of your charts via email, text message or social media. Locations Services can help you find nearby CSC locations when you travel. Refer to Attilla Danko’s excellent CSC web site home page for complete details on interpreting the preview and detailed charts: http://cleardarksky.com/csk A complete PDF user manual is available on my website: http://anythingbinary.com/iphone/myCSC/myCSC iOS User Guide.pdf This app is no longer free. A portion of every copy purchased will go to Attilla Danko to help support the ongoing operation of the Clear Sky Charts site.