A recent paper outlines water production rates for the comet C/2012 S1 (ISON). The study is based on observations of ISON as it approached the Sun in late 2013, and between the distances of 1.8 and 0.44 astronomical units (AU). The results are in agreement with other measurements of ISON taken by numerous instruments and techniques, and with many observatories around the globe and in orbit. The consistent results suggest that ISON experienced a large outburst of water, possibly resulting from fragmentation of the comet’s nucleus, when it was 0.6 AU from the Sun.

The study, “Evolution of H2O production in comet C/2012 S1 (ISON) as inferred from forbidden oxygen and OH emission,” was published in the journal Icarus. This work was supported by the Emerging Worlds Program. The NASA Astrobiology Program provides resources for Emerging Worlds and other Research and Analysis programs within the NASA Science Mission Directorate (SMD) that solicit proposals relevant to astrobiology research.