About BackyardHorizon
BackyardHorizon is a session-planning tool for astrophotographers as well as visual observing. It combines your equipment's optical capabilities, your site's actual sky visibility (from an uploaded panorama), live weather, and light-pollution (Bortle) conditions to recommend objects worth imaging on a given night, with suggested start/stop times. It does not use AI and is completely free to use.
I originally created this for myself because my backyard has a number of trees that block the horizon at different heights across the horizon. I wanted a way to quickly see which objects would be visible from my yard on a given night without having to manually check each one in Stellarium or SkySafari. Because I can easily see when they will clear any obstructions like our house or trees, it was a great way to very quickly get an initial plan together.
I hope it helps you too!
Suitability scoring is a planning heuristic based on standard rules of thumb (aperture-based limiting magnitude, field-of-view fit, Bortle/narrowband interaction, and Moon interference). It was never meant to be a rigorous imaging simulator, so always sanity-check recommendations against your own experience.
I still recommend using a planetarium app like Stellarium before you head out, but this app gives me a quick idea if a session is even worth it.
Changelog
v0.3.1 · August 27, 2026
- Name changed to BackyardHorizon to avoid conflict with another planning tool.
v0.3.0 · August 26, 2026
- Added a recommended minimum integration time on the object detail view, estimated from an object's brightness, your Bortle class, and your equipment. It's a simple heuristic (still being tuned) meant to flag whether a target is realistic in one night or will need multiple sessions across several evenings. If tonight's window alone won't be enough, you'll see a note estimating how many sessions it'll take.
- Added a "Sky Path" tab to the object detail view: plots the object's path across the sky over your horizon profile, so you can see at a glance where it'll be through the night.
- Visibility windows have always required the Sun to be at least 18° below the horizon before counting time as usable for imaging. Added a note when this is affecting a target's visibility window, so it's clear why start time is not always when the object clears the horizon boundary.
v0.2.1 · August 25, 2026
- Added a method to backup and restore your equipment and location settings since these are not stored on the server, only in your browser for privacy reasons.
v0.2.0 · August 23, 2026
- Fixed a few well-known nebulae (the Soul, Heart, and North America nebulae) showing up much smaller than they really are. Their catalog entries only reflected part of the nebula, not the whole thing.
- Object photos now show a real sky image with your equipment's exact field of view boxed on top of it, instead of an abstract diagram.
- Added a "Framing" tab on the object detail view: drag to reposition and rotate your frame, then copy the RA/Dec and rotation angle straight into ASIAIR, N.I.N.A., or similar setup software.
Data sources
- Deep-sky catalog: OpenNGC (CC BY-SA 4.0)
- Weather & geocoding: Open-Meteo
- Reverse geocoding: OpenStreetMap Nominatim
- Bortle class estimate: NOAA/EOG VIIRS satellite radiance (CC BY 4.0), computed locally from a bundled grid, not a live third-party lookup
- Astronomy calculations: Astronomy Engine
- Object thumbnails: Digitized Sky Survey via CDS/Aladin, NASA/JPL imagery (public domain)
- Object descriptions & distance: Wikipedia (CC BY-SA 4.0) and Wikidata (CC0)
Privacy
Your equipment profiles, saved sessions, horizon calibration, and Bortle class stay in this browser's local storage. Nothing is sent to a server except the location coordinates needed to fetch weather data and estimate light pollution for that spot. The light-pollution estimate is computed locally on our own server from a bundled satellite-derived grid, not looked up from a third party. Object descriptions and distances shown in the "About" tab are bundled with the app (sourced from Wikipedia and Wikidata) rather than fetched live, so opening that tab doesn't send anything to a server.
Author
Written by August "Gus" Branchesi. You can reach me at gus.branchesi@gmail.com