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R.E. Novak (Iona College), M.J. Mumma (Goddard Space Flight Center), M.A. DiSanti, N. Dello Russo (Catholic University of America, GSFC), K. Magee-Sauer (Rowan University), J. Levkov (Iona College)
Observations of Mars' atmosphere taken at NASA's IRTF on Jan. 8-12, 2002 (Ls ~ 306 degrees) will be compared to previously reported data taken on Jan. 12-14, 2001 (Ls ~ 103 degrees) and Mar. 18-21, 2001 (Ls ~ 133 degrees). Photolysis of ozone in Mars' atmosphere by UV sunlight (Hartley bands) produces a singlet-Delta state of O2; emissions from this state (1.27 micron band) are used as a tracer for atmospheric ozone above ~ 20 km since the singlet-Delta state is quench by carbon dioxide at lower altitudes. Water is detected by observing HDO absorption bands measured near 3.67 microns. We used CSHELL (0.5 arc-sec slit width, resolving power ~ 40,000) on the IRTF for these observations. The slit was oriented north-south on Mars and it was stepped east-west at one arc-sec intervals for the 1.27 and 3.67 micron settings. On Jan. 10, 2002 (and March 21, 2001), the slit was oriented east-west on Mars. No emissions from the singlet Delta state of O2 (1.27 micron setting) were detected for Ls ~ 306 deg; this provides an upper limit for the ozone column density above 20 km and is in direct contrast to observations taken at Ls ~ 103 and Ls ~ 133 when a sizable detection was observed in the southern hemisphere. These data will be presented along with near simultaneous measurements of water column densities retrieved from the HDO bands; maps of water column density for Ls ~ 306 degrees show less atmospheric water than on the 2001 dates. The HDO spectra from these opposite seasons will be used to determine the variation in the D/H ratio between the northern and southern hemispheres of Mars. Spectra taken at 4.67 microns show emissions from CO (2-1 vibrational band) and atmospheric absorptions of isotopic forms of CO and water; these spectra will also be presented. This work was partially funded by grants from NASA (NAG-11398) and NSF (AST-0205397).
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.