(Proposal ID) S16A-103 (PI) Ootsubo, Takafumi (Proposal Title) Cometary crystalline silicate before and after perihelion passage III (Abstract) Crystalline silicate is often observed in comets as an 11.3-micron resonant emission feature, and may be used for probing the early solar nebula. Because the formation of the crystalline silicate requires high temperature, they are thought to have been born from amorphous silicate at the inner region, and then transported toward the outer regions where comets were born in the early solar nebula. The study of strengths and peak wavelengths of crystalline features is important to investigate the conditions of the crystalline silicate formation. Comets are usually observed at the various heliocentric distances. It is suggested that the contrast in crystalline orthopyroxene increases near perihelion for the comet Hale-Bopp, while the ratio of crystalline-to-amorphous silicate is similar at the similar heliocentric distances before and after perihelion passage. To confirm this kind of dust properties, it is important to observe comets both before and after perihelion. Thus far, we don't have enough comet samples that we observed at both pre- and post-perihelion. In S15B the observations of C/2013 US10 and P/2010 V1 are allocated, and we can also observe these two comets in this semester S16A. Observations at pre- and post-perihelion provide us precious information on the dust evolution of the comet.