Overview
This application streamlines the traditional "intercept method" of sight reduction by combining a high-precision internal almanac, a digital sight reduction form, and an interactive plotting sheet into a single, offline-capable interface.
Built with modern web technologies, it replaces the need for physical Nautical Almanacs and HO-229 Volume tables, allowing navigators to reduce sights from the Sun, Moon, Planets, and 50+ navigational stars in seconds.
Key Features
Integrated Almanac
Calculates GHA, Declination, SD, and HP on the fly for any second in time using J2000 algorithms. No lookup tables required.
Digital Workflow
Follows standard HO-229 logic with auto-corrections for Index Error, Dip, Refraction, and Parallax. Data is persisted automatically.
Interactive Plotter
Visual plotting sheet with running fix capability. Handles date-aware advancement of LOPs for fixes spanning across midnight.
Star Finder
"Identify" mode scans the sky for bodies within 2° of your observed altitude, perfect for identifying stars in twilight.
Technical & License
Architecture: React 18, Tailwind CSS, Astronomy Engine. Delivered as a single HTML file for offline portability.
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY.