Brightness measurements of asteroids obtained with different telescopes may finally be brought together in a single shared database. A team from the Canary Islands is turning its internal prototype into a public platform for observatories around the world. From such data, astronomers can determine how small bodies rotate, what shapes they have, and what they are made of. If a potentially hazardous object appears, these observations sometimes need to be collected within just a few days.
Half a Million Asteroids to Start
The AsteroiDB platform already contains more than 15 million brightness measurements for over 500,000 different asteroids. The observations come from the two-meter Twin Telescopes (TTT), the Transient Survey Telescope (TST), and the ATLAS-Teide station installed at Teide Observatory. The latter is part of the international Asteroid Terrestrial-impact Last Alert System (ATLAS), created to monitor near-Earth objects.
The prototype was developed by Miguel Alarcón, Director of Scientific Operations at Light Bridges and a doctoral student at the Instituto de Astrofísica de Canarias. He is working on the project together with Miquel Serra-Ricart, who holds positions at both organizations, and Javier Licandro, a researcher at the same institute. The Solar System group has been using the development since 2024, and a grant from The Planetary Society’s Science and Technology Empowered by the Public (STEP) program will be used to make it openly accessible.
What a Light Curve Reveals
Photometry measures how bright an asteroid appears and how its brightness changes over time and at different wavelengths. A graph of these changes is called a light curve.
As an elongated body rotates, an observer alternately sees its broader and narrower sides. As a result, the amount of reflected light varies periodically. The period of these variations reveals the rotation rate, their pattern provides information about the object’s shape, and differences between wavelength ranges can indicate the material on its surface. Size is estimated indirectly.
A single night and a single instrument are usually not enough to provide the full picture. Light curves have to be assembled from measurements taken at different observatories, on different nights, and with telescopes ranging from relatively small instruments to those with the largest apertures.
A Common Archive of Light Curves Is Missing
The positions of asteroids in the sky have for several decades been collected in one place by the International Astronomical Union’s Minor Planet Center. These data are used to calculate orbits and track the motion of each body.
There has so far been no equivalent for photometry, according to the Instituto de Astrofísica de Canarias. Observations are scattered across observatory archives, institutional databases, and supplementary materials attached to scientific papers. Existing catalogs also tend to store finished conclusions, such as rotation periods, but not the time series from which those values were calculated.
Planetary Defense
Planetary defense stands to benefit most from this kind of coordination. According to Miguel Alarcón, characterizing a potentially hazardous object sometimes requires observations from very different telescopes to be assembled within only a few days.
An example of this type of work came in 2022. After NASA’s Double Asteroid Redirection Test (DART) spacecraft struck Dimorphos, the moon of asteroid Didymos, on September 27, astronomers on several continents used telescopes to monitor the bodies as they alternately eclipsed one another. It was the light curves that revealed that Dimorphos’s orbital period had shortened by 32 minutes, from 11 hours 55 minutes to 11 hours 23 minutes.
In the future, the platform is expected to simplify joint observing campaigns by the International Asteroid Warning Network (IAWN). Bruce Betts, Chief Scientist of The Planetary Society, expressed hope that AsteroiDB’s tools will accelerate the study of the physical properties of small bodies and improve the quality of that research.
A Common Language for Data
Another goal of the project is to create a common format for exchanging photometric observations. Only then will data from different instruments be able to be combined and analyzed consistently.
Javier Licandro, supervisor of Miguel Alarcón’s dissertation, emphasized that access to the database will be free and that users will also receive analysis tools. Further expansion of the database will now depend on observatories outside the Canary Islands that agree to contribute their own measurement series.
