Gaia is an excellent transient discovery instrument, covering the whole sky (including the Galactic plane) an average of 70 times over 5 years at high spatial resolution with precise photometry (1% at G=19) and sub-milliarcsecond astrometry. Gaia Science Alerts (GSA) is the first product of the Gaia mission released to the public, and is one of the core activities undertaken in Cambridge, and is described in Hodgkin et al. (2013:PhilTransA, 371, 20239). The first supernova was found during the early stage of the mission on 30th August 2014 and since then a couple of hundreds of other transient events were discovered: supernovae, AGNs or CVs.

These alerts, which cover a range of transient classes, have been the subject of an intensive multi-national follow-up effort. The purpose of spectroscopic and photometic follow-up of Gaia Alerts is two-fold. Firstly, additional data is required to verify the first transient discoveries from Gaia, to provide spectroscopic classifications of transients which can then be used to validate on-board spectroscopy, and to provide training data to test and refine the algorithms used in the Gaia Alerts pipeline. Secondly, spectroscopy and photometry can be used to do science with the first Gaia discoveries - to measure transient rates, and enable detailed analyses of individual objects. I will present an overview of the follow-up effort, along with the first science results from the Gaia Alerts project. Including the discovering of the first totally eclipsing AM CVn system.