Freeware from Sky & Telescope
The astronomy-related utilities listed below have been featured in Sky & Telescope and are available free of charge for personal use. This software is provided "as is," and without any warranty or support.
When you click on each link below, you'll go to a page that explains what the software does, shows a sample screen, and links to the downloadable file. Where applicable, we also link to a PDF of the corresponding article. To read the PDFs, you'll need Adobe Reader, which is available at no cost for most computers.
Mars Previewer II An interactive map for Mars observers.
Binoplan Design specs for right-angle, correct-view binoculars.
Cool Determine the cooldown time of a Newtonian reflector.
Flex How to stress a spheroidal mirror into a paraboloid.
Sec Find the optimum size of a Newtonian's secondary mirror.