Skip to content
João Montenegro

(714) Ulula, from three exposures to the scale of Portugal

A 41-kilometre asteroid caught crossing the Pleiades field on 25 July 2026, measured in three solved frames, placed on its orbit and set down over the map

25 Jul 2026Seestar S50Lisbon

(714) Ulula · M45

The Pleiades, the edited photograph that gives the Ulula measurements their context

(714) Ulula is a known main-belt asteroid. On the night of 25 July 2026 it crossed the sensor while the telescope was on the Pleiades, and it was recovered in all three independently solved 30-second source frames that caught it. The edited Pleiades photograph is context; the measured positions come from those three timestamped, plate-solved exposures.

The edited Pleiades image with the three measured Ulula positions drawn at the lower edge
The whole edited frame, with the three source-frame positions projected onto it through a validated registration (513 inliers, 0.29 px rms) and drawn live: the diamond at the lower edge, and the rectangle the detail below was cut from. Hover the diamond for each frame's time.
Detail of the edited Pleiades image with the three Ulula source-frame positions
The unscaled detail, at native resolution: the three measured positions, projected from the solved frames onto the edited image.

Three discrete samples

The registered blink: measured position as an open diamond, predicted position as a dashed circle
The registered blink is a derivative comparison of three discrete samples, not continuous video. Open diamond: measured. Dashed circle: predicted.

The blink compares the three solved frames after registration. The open diamond marks the measured position and the dashed circle the predicted one. Three samples are enough to confirm a known object at its predicted place and rate; they are not an orbit determination and not submission-quality astrometry.

Ulula's predicted position on the night, at the Seestar frame's size, beside the Pleiades. Pinch to zoom; drag to turn.
The matched source frame
One of the three source exposures, star-matched to the edited image so the positions can be carried across.

The orbit at the observation epoch

Ulula on its JPL orbit at the observation epoch, 25 July 2026 03:56 UTC, with the planets from JPL DE440s at that moment and the 4,000-orbit belt sample: a biased catalogue sample, not a density map. Drag to turn; pinch to zoom.

The film's orbit graphic is fixed at the observation epoch; its line reveal in the film changes visibility only. It uses JPL SBDB elements with local two-body propagation for Ulula, a pinned JPL DE421 planetary ephemeris, and a biased systematic sample of 4,000 numbered main-belt objects. That sample is not a literal density or completeness map.

At the scale of Portugal

The Ulula model over mainland Portugal at one kilometre scale: a 41.343 ± 2.348 km effective diameter, held over the country. Click it to fly to the model, the ground or Esc to come back; drag to turn. Physical context, not resolved telescope imagery, and not an impact location. Boundary from OpenStreetMap contributors (ODbL).

The rotating Ulula mesh is a scientific 3D model scaled to a sourced 41.343 ± 2.348 km effective-volume diameter. It is physical context, not resolved telescope imagery. Its placement over mainland Portugal is a same-scale size reference, not an impact location or prediction. Rotation in the film is time-compressed.

Twenty-eight seconds: the Pleiades field, the three measured positions blinked, the orbit at the observation epoch, and the shape model over mainland Portugal at one scale.

Published from session ulula-instagram-reel-2026-07-25 · run 20260727T213401Z-publication-science-video; session user-edits-2026-07-25 · run 20260727T161745Z-ulula-edited-image-overlay; session m45-mosaic-2026-07-25-ircut-30s · run 20260726T125202Z-asteroid-search. Every number above traces to a sealed measurement in those runs.