(Proposal ID) S11B-067 (PI) Aoki, Shohei (Proposal Title) Verification of CH_4 in the Martian atmosphere (Abstract) We propose the most reliable measurement of Martian CH4, for verification of its presence, variation and source. The wide spectral coverage, high spectral resolution, and the high sensitivity of SUBARU/IRCS enable us the first simultaneous measurement of multiple Martian CH_4 lines, telluric ^13CH_4 lines and Martian H_2O lines. The previous ground-based observations of Martian CH_4 (Mumma et al., 2009), mainly by CSHELL/IRTF, had large uncertainties. In particular, the contaminations from the telluric ^13CH_4 lines would be fatal in redshift, which were 10 - 50 times stronger than the Martian CH4 lines (Zahnle et al., 2011). Our simultaneous measurement with Martian CH4 and telluric ^13CH_4 can characterize and eliminate the contamination from the telluric ^13CH_4, which can establish the validity of Martian CH4fs presence and variation. The presence of CH_4 in the Martian atmosphere is remarkable because its sources are potentially biological or geological activities. Our simultaneous measurement with Martian CH_4 and Martian H_2O can constrain the source of CH_4 by comparison between the two maps.