TransitFinder is a desktop app that predicts upcoming observable exoplanet transits — filtered to your own observing site's real sky (target altitude, twilight, and moon) — using live data from the NASA Exoplanet Archive. Windows, macOS, and Linux.
Sites tab — define one or more observing sites by latitude, longitude, elevation, and timezone
Planet Database tab — cached NASA Exoplanet Archive catalog, with confirmed planets and optional TESS Objects of Interest candidates cached and dated independently
Search / Results tab — site-aware transit predictions with confidence tiers, elevation, moon data, and CSV/XLSX export
- Site-aware predictions — filters transits by minimum target altitude, twilight requirement (civil/nautical/astronomical/custom), and moon illumination/separation for a chosen observing site, not a generic table of transit times
- Two NASA data sources — confirmed transiting planets (NASA Exoplanet Archive
pstable) and TESS Objects of Interest candidates (ExoFOP-TESS, mirrored weekly into NEA's own TOI table), each cached and dated independently - Self-consistent ephemerides — period and epoch are always taken from the same publication, never mixed across papers, avoiding a real NASA Exoplanet Archive data-quality pitfall that can silently produce a wrong predicted time
- BJD_TDB → UTC correction — every predicted time is corrected for barycentric light-travel-time and the TDB-UTC offset rather than left as a raw archive value
- Confidence tiers — every prediction shows a propagated timing uncertainty and a color-coded confidence tier (High/Medium/Low/Very Low/Unknown) instead of a bare timestamp
- Partial-visibility search mode — a minimum-visible-percent slider, matching Swarthmore Transit Finder's own option, so a transit only partially observable at your site can still show up
- Saved target lists — recall a named watchlist of targets across sessions for a long-running observing campaign
- VSX lookup — right-click any result and check whether the target is already registered in the AAVSO Variable Star Index, before you spend a night gathering light curve data for it
- CSV / XLSX export of search results
- Diagnostics — a live, saveable session log of every button click, search run, and NASA Exoplanet Archive network call
| Windows | Windows 10 (64-bit) or later |
| macOS | macOS 11 (Big Sur) or later, Apple Silicon or Intel |
| Linux | 64-bit, glibc-based |
| .NET | Not required — runtime is bundled in the download |
| Internet | Needed to refresh the planet catalog from the NASA Exoplanet Archive; searches themselves run offline against the cached copy |
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Download the latest release from Releases
Platform File Windows (64-bit) TransitFinder-v{version}-win-x64.zipmacOS (Apple Silicon) TransitFinder-v{version}-osx-arm64.dmgmacOS (Intel) TransitFinder-v{version}-osx-x64.dmgLinux (64-bit) TransitFinder-v{version}-linux-x64.zipWindows/Linux: extract the zip and run
TransitFinder/TransitFinder.exe. macOS: open the.dmgand drag TransitFinder to Applications (see the Windows Security Warning / macOS first-launch notes below). -
Go to Planet Database and click Refresh Database Cache to download the planet catalog
No installer required. No .NET installation required.
TransitFinder is not code-signed (that requires a paid certificate plus a hardware security key, not currently justified for a free, open-source project), so Windows may flag it as coming from an unrecognized publisher. This is expected — here's how to get past it:
Most users see this — "Windows protected your PC" (SmartScreen): Click More info, then Run anyway.
Less common — the app opens briefly then silently closes, no error at all: This is Smart App Control, a stricter Windows 11 feature enabled by default on some newer installs. To fix:
- Settings → Privacy & security → Windows Security → App & browser control → Smart App Control → turn it Off.
- Restart your PC — the change needs a reboot to take effect.
- Delete your existing TransitFinder folder and re-download and re-extract a fresh copy (a blocked file may already have been partially removed).
- Right-click
TransitFinder.exe→ Properties → check Unblock at the bottom → Apply, then launch again.
macOS: TransitFinder is ad-hoc signed but not notarized (same reasoning as above — a paid Apple Developer account isn't currently justified for a free, open-source project), so the first launch requires right-click → Open → Open in the security dialog. After that it launches normally.
- Add your observing site in the Sites tab (latitude, longitude, elevation, timezone)
- Go to Planet Database and click Refresh Database Cache
- Go to Search / Results, pick your site and criteria, and click Search
- Export results to CSV/XLSX, or select rows in Planet Database and click Add Selected to Search to build a target list
See the built-in User Guide (Help → User Guide) for full documentation.
This project is licensed under the MIT License — see the LICENSE file for details.
© Art Trail 2026 Data from the NASA Exoplanet Archive and ExoFOP-TESS Developed with Avalonia UI and .NET 8