This page serves to assist users with their high-level planning. The tables and widgets found here are meant to provide an ‘at a glance’ understanding of the astronomical conditions and crude star/planetary placements at ST1. Much more powerful applications and systems exist behind the firewall. See the HW & SW page for those.


The ‘Clear Sky Chart’ is the astronomer’s go-to forecast. It shows the conditions over the next 48 hours and is pretty accurate. The data comes from a model developed by Allan Rahill of the Canadian Meteorological Center. CMC’s numerical weather forecasts are unique and specifically designed for astronomers. Locate a column of blue blocks and that’s when the sky will be best. The darker the blue the better. A more detailed explanation is here, but the short version is: the clear sky chart predicts hourly cloud cover, atmospheric transparency and seeing.



The 7timer forecast is equally indispensable and is generated real-time. The icons are a little easier to read than the color gradients of other charts and the temperature values are nice. The extra day of forecast here is also useful.



Another favorite is the Metro Blue Astronomical forecast. Here you’ll find hourly detail on different cloud levels and there are 2 different indexes foe seeing, jet stream, temp, humidity and you’ll find the planets that are up. It’s very comprehensive table based collection of data that reads like a TV guide.


Here is a simple chart of the universe overhead. The map is a current and gives the major objects (constellations, planets, etc) for the entire sky. There are red lines for the ecliptic and horizon as well as the alpha star names.



This little application creates a view of the Earth with daytime and nighttime areas shaded appropriately. The image generated is of the apparent disk you would see if you were in a spacecraft looking back at Earth.



Lastly is a planetary ephemeris table. This table is updated monthly so it will always be at most few degrees/minutes from true. For sun and moon position data please click here.