The Near-Earth Object Wide-field Infrared Survey Explorer ( NEOWISE ) mission observed comet C/2013 A1 ( Siding Spring ) three times at 3.4 \mu m and 4.6 \mu m as the comet approached Mars in 2014 .
The comet is an extremely interesting target since its close approach to Mars in late 2014 will be observed by various spacecraft in-situ .
The observations were taken in 2014 Jan. , Jul .
and Sep. when the comet was at heliocentric distances of 3.82 AU , 1.88 AU , and 1.48 AU .
The level of activity increased significantly between the Jan. and Jul .
visits but then decreased by the time of the observations in Sep. , approximately 4 weeks prior to its close approach to Mars .
In this work we calculate Af \rho values , and CO/CO _ { 2 } production rates .