100% offline · No account

Your observing logbook,
offline under the stars.

At a dark-sky site there is no signal, no white light and no patience for typing. Nightfield records what you saw — object, scope, eyepiece, magnification, seeing — and keeps every entry on your phone, forever.

Works in airplane mode No tracking, no ads Export anytime
The problem

Paper logs get lost. Apps ruin your night vision.

Amateur astronomers are told to keep a log — it is how you learn the sky and how observing clubs certify your Messier certificate. In practice the log is a damp notebook or nothing at all.

No signal where the sky is dark

The best observing sites are rural by definition. An app that needs a connection is an app that fails exactly when you need it.

White light undoes 20 minutes of work

Dark adaptation takes about twenty minutes and a bright screen destroys it in seconds. Most apps have no real red mode.

Arithmetic in the cold

Working out magnification from focal lengths at 2am with gloves on is how details stop getting recorded at all.

What's inside

A real logbook, not a note-taking app.

Every feature runs on-device. No account, no sync, no third-party SDKs — the whole catalogue ships inside the app.

Core

Detailed observation log

Object, date and time, telescope, eyepiece, magnification, seeing, transparency, your rating and free-form notes — the fields a real logbook needs.

Core

The full Messier catalogue

All 110 Messier objects, the planets and a set of bright showpieces, bundled offline with type, constellation, magnitude and best season.

Core

Catalogue completion

Watch your Messier count climb toward 110. This is the progress observing clubs certify — and it never finishes in one night.

Core

Magnification worked out for you

Record your telescope and eyepiece focal lengths once. Every entry gets the right magnification without you doing division in the dark.

Core

True red-light Night mode

The whole interface drops to deep red on black, so checking your log at the eyepiece does not cost you your dark adaptation.

Core

Sites rated by Bortle class

Record where you observed and how dark it was, so you know why the same object looked different on two different nights.

Insights

Charts from your own log

Seven-night and six-month trends, seeing distribution, object-type breakdown and which telescope actually gets used — computed on-device.

Gamification

Streaks that respect the weather

Streaks count consecutive weeks you got out, not nights — because clouds are not your fault. Plus a monthly goal you set yourself.

Gamification

Achievements worth earning

First Light, Messier 10/25/50/110, Grand Tour of the planets, Ten Nights Out — milestones drawn from real observing goals.

Organization

Search, filter, sort and tag

Full-text search across objects, notes and tags. Filter by favourites or archive, sort by date, name, rating or magnification.

Organization

Plan tonight's targets

Bookmark objects you want to find. They stay on the Tonight screen — an in-app agenda, never a push notification.

Your data

Export JSON and CSV

A full restorable backup or a spreadsheet-ready log for your observing club. Written to a file you choose — no cloud involved.

Customization

Light, Dark and Night

Three real themes, five accent colours and three layout densities — because a screen you use at 2am should be one you chose.

Privacy

Encrypted on device

Your log — including private notes and the places you observe from — is stored in an encrypted local database and never leaves the phone.

Privacy

There is no server to trust.

Nightfield collects nothing, because there is nowhere for it to send anything. The app declares exactly one permission — INTERNET — used solely to display this site's privacy policy inside the app.

No data collected

No analytics, no crash reporting, no advertising identifiers, no third-party SDKs of any kind.

No account, ever

Nothing to sign up for and no email address to hand over. Open the app and start logging.

You can leave with your data

Export a complete JSON backup whenever you like, or wipe everything from Settings in two taps.

Clear skies are coming.

Free. No ads, no in-app purchases, no subscription.

Get it onGoogle Play

com.nightfield.nightfield · Android 7.0 and up