Free Astronomy Calculators and Telescope Utilities

Explore Ontario Telescope’s collection of free astronomy calculators, astrophotography tools, and telescope utilities for visual observers, beginners, and experienced imagers. Calculate autofocuser step size, flat-frame exposure settings, guide scope suitability, double-star resolution, polar alignment tolerance, upcoming ISS passes, and celestial objects visible from your location.

Each free browser-based tool provides practical results to help you plan observing sessions, configure your telescope and camera, improve astrophotography performance, and spend less time guessing under the night sky. No account, subscription, or software download is required.