Sidereal

Plan, shoot, and perfect your astrophotography with the tools you need in the field. Sidereal brings together exposure calculators, an interval timer, a celestial compass, a deep sky object catalog, weather forecasting, and equipment management. All in one app designed for use under dark skies.

Whether you're capturing your first Milky Way shot or imaging faint nebulae with a star tracker, Sidereal helps you get the settings right, stay on schedule, and find your targets.

EXPOSURE CALCULATOR

Get sharp stars every time. Calculate maximum exposure times using the classic 500 Rule or the more precise NPF Rule. Select your camera and lens from a built-in equipment database, choose a target object, and get recommended settings instantly, including field of view and total integration time estimates.

INTERVAL TIMER

Track your imaging session frame-by-frame. Set your exposure length and total duration, then let the timer count down with on-screen progress, notifications, and optional floating overlay so you can use other apps.

CELESTIAL COMPASS

Find Polaris, the Milky Way, and deep sky objects using a real-time compass with altitude and azimuth display.

DEEP SKY OBJECT CATALOG

Browse a curated catalog of galaxies, nebulae, star clusters, and more. Filter by object type, difficulty, or what's visible tonight from your location. Each entry includes visibility windows, framing information, and imaging difficulty. You can plan your targets before heading out.

SKY PLANNER

Simulate the sky for any date, time, and location. Plan sessions days or weeks ahead by seeing which constellations and objects will be visible. Perfect for trips to dark sky sites.

WEATHER & CLEAR SKY ALERTS

Check cloud cover forecasts at a glance. Enable Clear Sky Alerts to get notified when conditions are ideal for imaging, so you never miss a clear night.

GEAR LOCKER

Manage your cameras, lenses, and telescopes. Sidereal includes a searchable database of camera sensors and lens specs. Add your own gear, mark favourites, and select equipment directly in the calculator.

NIGHT VISION MODE

Preserve your dark adaptation. Sidereal can automatically switch to a red-on-black interface using your phone's light sensor, or set it manually. Every screen is designed to be usable in the dark.

WEAR OS COMPANION

Control your session from your wrist. The Wear OS app syncs with your phone and includes:

- Interval timer with ongoing activity tracking

- Compass with constellation overlays

- Sunrise, sunset & astronomical twilight times

- Clear sky conditions

- Red-light torch

FREE FEATURES

- 500 Rule calculator

- Interval timer with notifications & overlay

- Basic compass

- Session checklist

- Equipment database

- Light pollution lookup

- Night vision mode

PRO UPGRADE (one-time purchase)

- NPF Rule & star tracker mode

- Deep sky object targeting

- Sky Planner

- Clear Sky Alerts

- Auto night vision

- No ads

Available in 15+ languages. No account required. No subscriptions. Sidereal Pro is a single purchase that unlocks everything, forever.

Built by an astrophotographer, for astrophotographers.