Program: GN-2020A-Q-131

The discovery and study of the optical source SSS17a/AT2017gfo associated with the binary neutron star merger GW170817 has forever changed the field of astronomy and provided confirmation of Binary Neutron Star mergers (BNS) as the source of r-process elements (Coulter et al. 2017, Smartt et al. 2017, Abbott et al. 2017 for a summary of the campaign). While the primary evidence for this is the rapidly decaying light curve (1.5 mag/day) consistent with the radioactive decay of a kilonova, our collaboration was the only group that was also able to identify spectroscopic features of light r-process elements, specifically Cesium and Tellurium, indicative of a blue or low opacity kilonova (Smartt et al 2017). To further advance our understanding of kilonovae and r-process elements, in particular the heavy r-process elements (as kilonovae are not axisymmetric objects), we need optical and near-infrared spectra as a function of time on a larger sample. Advanced LIGO (aLIGO) and Advance Virgo (AdVirgo) have been online since April 2019 for the third observing run (O3) and is expected to run through April with possible extensions through June 2020 (Abbot et al. 2019). The median 0.9 Credible Region is very well suited to the combined survey power of Pan-STARRS1 and Pan-STARRS2 for identifying fainter candidates for spectroscopic follow-up. This proposal is for TOO queue time for follow-up optical and near-infrared spectroscopy with GMOS and GNIRS on 1-2 kilonova from aLIGO/AdVirgo alerts to complement CFHT u, UKIRT JHK and Pan-STARRS grizy photometry. Spectroscopic follow-up of other rare transients will be carried out as a secondary program.