First Detection of the SiO (v= 3,J= 2–1) Maser Emission from χ Cygni

From the simultaneous observations of SiO v = 3, J = 2-1 and J = 3-2 masers, SiO v = 3, J = 2-1 maser emission was detected for the first time toward the S-type Mira variable χ Cyg. The line was a single spike and was redshifted with respect to the stellar velocity. The SiO v = 3, J = 3-2 maser emission was not detected from this star. However, for the O-rich Mira variable TX Cam, SiO v = 3, J = 3-2 maser emission was detected, while v = 3, J = 2-1 maser was not detected. Two possible line overlaps were adopted as an explanation of these observational results.