  We have used the unique far-UV imaging capability offered by a sounding
rocket borne instrument to acquire observations of C/2012 S1 (ISON) when its
angular separation with respect to the sun was 26.3deg, on 2013 November 20.49.
At the time of observation the comet's heliocentric distance and velocity
relative to the sun were rh = 0.43 AU and rh_dot = -62.7 km s^-1. Images
dominated by C I 1657 A and H I 1216 A were acquired over a 1e6 x 1e6 km^2
region. The water production rate implied by the Lyman alpha observations is
constrained to be Q_H2O approximately 8e29 s^-1 while the neutral carbon
production rate was Q_C approximately 4e28 s^-1. The radial profile of C I was
consistent with it being a dissociation product of a parent molecule with a
lifetime approximately 5e4 seconds, favoring a parent other than CO. We
constrain the Q_CO production rate to 5(+1.5, -7.5)e28 s^-1 with 1sigma errors
derived from photon statistics. The upper limit on the Q_CO/Q_H2O < 6%.
