The paper by Li-Xin Li and Bohdan Paczyński discusses the transient events that occur from the merger of neutron stars (NS+NS) or a neutron star and a stellar mass black hole (NS+BH). These mergers eject a small fraction of matter at sub-relativistic velocities, leading to the rapid decompression of nuclear density matter into neutron-rich nuclei, most of which are radioactive. The radioactivity provides a long-term heat source for the expanding envelope, resulting in a brief transient with peak luminosities in the supernova range and most of the radiation in the UV-optical domain. The authors present a simple model and analytical formulas to estimate the parameters of such transients based on poorly known input parameters. They suggest that these mergers may be detected as rapid transients in high-redshift supernova searches, and possibly already observed by Schmidt et al. (1998) as mysterious optical transients without visible host galaxies. The paper also explores the implications of these events for gamma-ray bursts and gravitational wave detection.The paper by Li-Xin Li and Bohdan Paczyński discusses the transient events that occur from the merger of neutron stars (NS+NS) or a neutron star and a stellar mass black hole (NS+BH). These mergers eject a small fraction of matter at sub-relativistic velocities, leading to the rapid decompression of nuclear density matter into neutron-rich nuclei, most of which are radioactive. The radioactivity provides a long-term heat source for the expanding envelope, resulting in a brief transient with peak luminosities in the supernova range and most of the radiation in the UV-optical domain. The authors present a simple model and analytical formulas to estimate the parameters of such transients based on poorly known input parameters. They suggest that these mergers may be detected as rapid transients in high-redshift supernova searches, and possibly already observed by Schmidt et al. (1998) as mysterious optical transients without visible host galaxies. The paper also explores the implications of these events for gamma-ray bursts and gravitational wave detection.