Free software · MIT · embeddable anywhere
Reconstruct what the witness saw.
Draw the shape. Record how it moved. Replay it against the sky that was actually over that place, at that hour, on that date — the Sun, the Moon, the stars, the weather on record, the ground itself. Not an artist's impression: a reconstruction anyone can check.
Two things to do with it#
Describe your own sighting
Draw what you saw and record how it moved, then say when and where — and the sky of that moment appears behind it, along with the weather that was on record. Correct the shape until it matches. What you get is a file that is yours; there is no account and nothing is uploaded.
Open the editor →
Put it on your own site
Two lines of HTML place a reconstruction in an article, a case file or a report — your recording, on your host, under your name. No framework, no build step, no dependency on this site once you hold the files. It is MIT: use it, change it, redistribute it, fork it.
Read the documentation →
A testimony is an angle, not a measurement#
Nobody perceives metres. A witness perceives an angle: the thing covered a thumbnail at arm's length, a fifth of the windscreen, two full Moons. “About thirty metres long” is a conclusion drawn from a distance they could not perceive either, and the two errors multiply.
So a UFO@home recording stores how big the object looked, in degrees, and stores no real size and no real distance anywhere. Metres come back in one case only: when the object was seen to pass behind or in front of something whose position is known. That is an inequality, and the tool reports it as one — including, most of the time, “unknown”.
The object is drawn as a flat shape on the witness's field of view, never as a solid body placed in space. That is deliberate. Assuming a craft at a distance is already an interpretation, and it quietly rules out the explanations that matter most: a halo, a planet, a satellite, an aircraft's landing light, a lenticular cloud. A 2D shape assumes only what the witness actually claimed — that this is what reached their eye.
Which is why a case with several witnesses is several recordings, not one. Each states what one person saw from where they stood, and a reconstruction can step from one to the other — the reader through a picker, the author by placing the others in the scene and opening their accounts from there. Two people a hundred metres apart did not see the same thing, and the format is built so that the difference has somewhere to live.
Everything else is looked up or computed#
The witness supplies the object. Nothing else in the scene is left to memory.
The sky#
Sun, Moon and its phase, planets, a star catalogue down to magnitude 7.5 — positioned for that instant and that latitude. The Milky Way and the zodiacal light are integrated along the line of sight, not painted as a texture. Point at any of it and it names itself: “Venus, mag −4, 8° above the horizon”.
What else was up there#
Comets at their own apparition, meteor showers with their radiant and rate over a sporadic background, satellites with the Earth's shadow worked out to say whether one could have been lit at all.
Ice and water#
22° and 46° haloes, sundogs, pillars, tangent and circumzenithal arcs — every angle derived from ice's refractive index, none of them stored. Rainbows and moonbows traced through a spherical drop.
The weather that day#
Cloud cover, cloud base, rain, snow, storms, wind — read from ERA5, the ECMWF reanalysis, hourly and worldwide from 1940 on. The exact query is kept in the file, so the claim stays checkable decades later.
The ground#
Real relief and aerial imagery around the witness, and the decor that got in the way: buildings, trees, streetlights, vehicles, windows, other witnesses — with their lights, their flash rates and their tracks.
The instrument#
An eye is not a lens. Naked-eye viewing maps an angle to an angle; a camera maps it to
f·tan θ, with a sensor, a focal length, an aperture and an exposure that
draws star trails and dots a flashing light. Switch the device and the whole frame changes
— the same sighting through three of them.
Only what that device could actually have been set to is offered: an Instamatic had one aperture and one shutter speed, so there is nothing to choose, and a camera that did not exist yet is flagged against the observation's own date.
Every source is named where its data is reported, with the attribution its licence requires — and can be swapped for another. The picker is the credit. What is still missing, and what each item is waiting on, is on the roadmap.