Finding GRBs and Asteroids in Fink

The transients observed through Fink allow us to study both very near and very distant astronomical objects simultaneously!

This work addresses the challenge of associating signals from optical telescopes with high-energy astrophysical events such as gravitational waves, gamma-ray bursts (GRBs), and neutrinos. To tackle this, we developed the Fink-MM (Fink Multi-Messenger) module, a real-time system for identifying optical counterparts to multi-messenger alerts using spatial and temporal coincidence filtering, enhanced with statistical methods tailored to GRBs. This led for example to the successful identification of GRB 230827256 optical counterpart!

While working on fast transient identification, it became clear that foreground moving objects, including potentially new and unreported asteroids, were posing a challenge. Therefore, a second major contribution is Fink-FAT (Fink Asteroid Tracker), a tool designed to detect and reconstruct the trajectories of previously unknown asteroids using sparse and noisy data from optical alerts. By estimating orbital parameters and generating ephemerides, Fink-FAT enables the classification and confirmation of mobile objects that would otherwise contaminate searches for extragalactic transients. The tool was validated through follow-up campaigns with ground-based telescopes, which confirmed known objects, identified irregular moons of Jupiter, and potentially revealed new, uncatalogued solar system bodies. This work is described in Le Montagner et al., 2023.

Finally, we explored the need for follow-up infrastructure to support real-time discovery. To address this, we initiated the design of GVOM (Ground Variable Object Monitor), a coordination system for scheduling and managing follow-up observations of transient candidates. Though still a prototype, GVOM represents a step toward a fully automated multi-messenger detection and characterisation pipeline. The work showcases how scalable, distributed tools can prepare for the data-intensive future of time-domain astronomy with the upcoming LSST.

All the above contributions are part of the PhD thesis, High-Energy Transient Universe in the Era of Large Optical Surveys, by Dr. Roman Le Montagner, defended at Universite Paris-Saclay, 2024.