Observations of the circumstellar gas shells around Betelgeuse and Antares

K i resonance line (lambda7699) emission has been detected from the circumstellar gas shell surrounding Betelgeuse (α Ori). A shell diameter of 4''--8'' (80--160 stellar radii) is indicated. New observations of the Ca ii infrared triplet line cores are used to obtain a lower limit to the Ca+ (and, hence, K i) shell radius. The 8542 A line in α Ori does not show a circumstellar absorption core, and the shell radius limit, R/sub shell/greater than or equal to31 R/sub star/, is estimated. A 108 mA circumstellar core is seen in the 8542 A line in Antares (α Sco), and a shell radius R/sub shell/approx. =4.0 R/sub star/ is suggested