GRANDMA (Global Advanced Rapid Network Devoted to the Multimessenger Addicts) is an international collaboration gathering about 90 physicists and more than 20 observatories in more than 15 countries.
GRANDMA is born at IJCLab under the impulse of Sarah Antier (PI of the collaboration) after the observation of GW170817 and all the associated optical follow-up. It clearly appeared that if one wants to catch the entire phenomenon (merger, gamma ray burst, kilonova, afterglow…) a global coordination of the optical telescope facilities is in particular required.
The GRANDMA network covers all the time zones and both hemispheres. In case of LIGO-Virgo alerts, this allows to look immediately after the optical counterpart, if it exists, and to measure the first points of the light curve of a possible kilonova. The network posseses wide-field of view telescopes, like TAROT, narrow-field but more sensitive telescopes and spectroscopic facilities in order to characterize the identified sources.
The collaboration software is hosted at IJCLab within the Virtual Data computing center.