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R. E. Novak (Iona College), M.J. Mumma (NASA/GSFC), M.A. DiSanti, N, Dello Russo (GSFC/Catholic University), K. Magee-Sauer (Rowan University)
The 1Delta state of O2 is produced on Mars by photolysis of ozone by sunlight; detection of these emissions is used as a tracer for atmospheric ozone after accounting for collisional quenching at low altitudes. We used CSHELL (0.5 arcsec slit width, resolving power ~ 40,000) at IRTF to observe the 1.27 micron band of O2 (1Delta -3Sigma transition) on Mar. 1, 1997 (Ls = 84.5 deg), Mar. 21, 1999 (Ls = 112.5 deg), and Jul. 5, 1999 (Ls = 165.2 deg). The slit was oriented along the north-south direction on Mars and the slit was stepped east-west to produce spectra at several different locations separated by 1-2 arcsec. The spatial resolution was ~ 1.0 arcsec (500 km or 10 degrees latitude at the sub-earth point (22.5 degrees latitude on Mars) for data taken on Mar. 1, 1997 when Mars was 0.70 a.u. from earth). Eight emission lines of O2 were detected in the range between 7898 and 7917 cm-1. Retrieved rotational temperatures varied from 150 K near the poles to 200 K near the equator reflecting atmospheric temperatures at the altitude of line formation. Ozone column densities retrieved at mid-northern and mid-southern latitudes are greater than those found at the equator. Quantitative results for the three observing intervals will be presented and discussed. This work is partially funded by NASA/JOVE grant #NAG8-1273.