Features

What TwilightScan does

TwilightScan is free.

A free service for the community and people who love the night sky. Free for home use: no cost, no subscription.

For a business, school or observatory, ask about a license.

A recorder that runs on a computer at your house, next to a sky camera. It records every night, finds what moved, and has a list ready in the morning. Below is what it does today, then what is coming.

What it does today

Built

All of this is in the recorder you install now.

How it sorts the lights

It sorts each light by how it behaves over time. Every call comes with its reasons, so you can see why.

Plane
A flash that repeats every half second to two seconds, like anti-collision strobes, on a steady path.
Satellite
A steady light, no blinking, on a straight path at constant speed. Also the smooth arcs a wide-angle lens bends a pass into.
Meteor
A short, thin, dead-straight streak. The trail is measured on the video to check it really is straight.
Unidentified
A real point of light that fits none of the above. Kept for you to look at, not guessed.
Filed away
Insects near the lens (wavy, soft or zigzag), cloud and glare, noise, and headlight glow from the road. Kept apart from the list, and counted.

Recording

  • Records from 15 minutes before dusk to 15 minutes after dawn, worked out for your location each day.
  • Pulls the camera's RTSP stream at full resolution and writes 10-minute segments, one folder per night.
  • A quick detector runs as each segment closes. A thorough full-resolution pass runs in the morning and replaces it.
  • Checks the camera every 30 seconds and marks any time it was offline on the night.

Sky and camera

  • Sky mask: finds the sky at dusk and dawn and ignores roofs, trees and the camera's time stamp.
  • Notices when the camera has moved and redraws the mask. Emails you if it can't.
  • Star calibration: works out which way the camera points and how its lens bends, from the stars.
  • Bright named stars drawn over the live camera view, for lining it up.
  • Shows the camera's stream, bitrate, exposure and clock on Dahua-style cameras such as Amcrest.

Sky conditions

  • Measures how clear and dark the sky is every 10 seconds.
  • Checks hourly cloud cover from Open-Meteo as a second opinion.
  • Files away lights seen through cloud, so a cloudy hour doesn't fill the list.
  • Coming up tonight: ISS, other stations, bright satellites and Starlink trains, from CelesTrak orbits.

The review desk

  • Inbox of the night's lights, each with a clip and the reasons for its type.
  • Mark each one reviewed, change its type, star it and add a note.
  • Timeline: what crossed the sky, quarter-hour by quarter-hour.
  • Sky map: every path of the night drawn on the night's best photo.
  • History: the last 14 nights by type.

Pictures of the night

  • Best of the night: frames averaged at the clearest, darkest moment, showing far more stars.
  • Star trails over the longest clear stretch, up to two hours.
  • A time-lapse of the whole night.
  • Made every morning after the thorough pass.

Email

  • A morning report once the night's pictures are made.
  • Alerts when the camera goes down, the camera moves, or the disk runs low.
  • Sent over TLS. Emails never include your exact location.

Storage

  • Deletes raw video older than 7 days, or the oldest first when space runs low.
  • Never deletes clips, pictures or results, tonight's recording, or a night you marked to keep.
  • Every deletion is logged.

Security

  • HTTPS out of the box, with its own certificate. Install it once per device to drop the warning.
  • One desk password, set on first visit. API tokens for scripts.
  • Video and the camera password stay on that computer.

Install and help

  • Docker image with one compose file and one settings file. A Linux service and Windows also work.
  • Send a support ticket from Help on the desk.
  • The ticket carries the recorder version, camera health and the end of the log, with the camera password, addresses, location and emails removed first.
  • Docs, real catches and our own station on this site.

Not yet: naming the exact satellite or flight behind a clip. The desk says “names need calibration” and flight matching is not set up. Types come from how the light behaves.

Coming: stations and shared clips

Coming

Planned, not built. No dates yet. Today the only station on this site is our own, Station YBD, added by hand.

How sharing a clip will work

  1. 1
    Link the desk

    The desk shows a short code. You type it on this site while signed in, name the station and set a rough place.

  2. 2
    Nightly counts

    The desk sends planes, satellites, meteors, unidentified and clear or cloudy, once a night. No video. Your station gets a public page.

  3. 3
    Share a clip with one button

    The desk makes the web cut itself: cropped around the path, sky mask applied, a credit with the station name burned in. It uploads straight to cloud storage.

  4. 4
    Manage it from your account

    See your shared clips and unshare any of them. Unsharing removes it from the site and from storage at once.

Also planned

  • Clip pages. One page per shared clip, with the time, the type and why, and your note.
  • Votes. One up-vote per signed-in person, with top tonight, this week and all time.
  • Comments. Signed-in, plain text, with a report button.
  • I saw it too. Say you saw it, or link your own station's clip of the same minute.
  • Seen from two roofs. The same light caught by two stations within a minute.
  • Share and download. Copy link, social sharing, and the credited clip to download.

Privacy

  • Your video stays at your house. Nothing leaves unless you press share on a clip.
  • The site never gets full frames: only the short cut the desk made, with the yard and houses blacked out.
  • Your location is rounded to about 10 km before it is stored. The exact spot never leaves the desk.
  • Never public: your address, the camera's address or password, or footage you didn't pick.
  • Nightly counts can be turned off. Unsharing takes a clip down at once.
Install the recorder See real catches How it works