nightglass · engine 2026.1.0
Know what is worth observing tonight, and why.
Most observing plans fail on arithmetic nobody did: the target never clears the trees, or the Moon is full behind it, or it is simply too faint for the aperture you own. nightglass does that arithmetic in the open, from real ephemerides and a real forecast, and shows every measurement behind every score.
Tonight, from a default site
2026-10-03 · 13:53–23:27 UTC
Dark window
10 h
Sun -66° at mid-night
Cloud
0%
0% low
Moon
48%
8° altitude at mid-night
Conditions
Live
Open-Meteo
01 · star
Altair
67
good
Altair scores 67/100 — worth the set-up. Observe between 13:53 and 19:02; it peaks at 70° at 13:53, which is your best chance of the night.
02 · star
53Alp Aql
67
good
53Alp Aql scores 67/100 — worth the set-up. Observe between 13:53 and 19:02; it peaks at 70° at 13:53, which is your best chance of the night.
03 · star
Vega
67
good
Vega scores 67/100 — worth the set-up. Observe between 13:53 and 18:47; it peaks at 72° at 13:53, which is your best chance of the night.
Scores above are computed for a default site so the first paint is a real verdict. Set your own site and the ranking re-cuts immediately.
Real horizon, not an assumption
You tell nightglass how high your trees or roof are. The altitude curve is integrated across the real astronomical night and anything below that obstruction is hatched out, not quietly ignored.
Surface brightness, not just magnitude
An extended object at magnitude 9 spread over three degrees is a different night out from a compact magnitude 9 knot. The reach factor splits its weighting on angular size for exactly that reason.
Sealed and replayable
Every score and every mutation is sealed into a SHA-384 chain. You can replay it and find the first broken link, and the session card you export carries the seal.
Runs in the browser and on your desktop
nightglass ships as a desktop app for macOS, Windows and Linux. Same engine, same API, tray notifications when a target reaches its best altitude.