Initiated by the gravitational waves group (pole A2C) of IJCLab, GRANDMA (Global Rapid Advanced Network Devoted to the Multi-messenger Addicts) is an international network of 25 telescopes of different sizes, both photometric and spectroscopic facilities, spread across20 observatories located in both hemispheres. By covering a large number of time zones, this network can carry out rapid and effective monitoring in the event of an alert.
GRANDMA aims to coordinate follow-up observations of gravitational-wave candidate alerts, especially those with large localisation uncertainties, to reduce the delay between the initial detection and the optical confirmation. An algorithm, developed jointly by IJCLab and the american GROWTH collaboration, permits better optimisation of the characteristics of the telescopes in the network in order to maximise their use and observe large areas of the sky in the first few hours following a signal.
Resulting from the LIGO/Virgo O3 observation run, GRANDMA has demonstrated its effectiveness by tracking 90% of the alerts (49 candidates out of 56). The next O4 observation campaign scheduled between 2022 and 2023 will mark a new leap in the sensitivity of gravitational wave detectors.
In addition, GRANDMA initiated a collaboration between professionnal and amateur worlds with a participatory science project called Kilonova-catcher. This project, supported by University of Paris, uses amateur astronomers from around the world to contribute to the monitoring of observations.