Mapping of Mars O-2((1)Delta) dayglow

We observed the O-2((1)Delta) dayglow at 1.27 mu m near northern midsummer (L-S = 112 degrees) with a long-slit cryogenic echelle spectrograph (CSHELL at the NASA Infrared Telescope Facility) having a resolving power of 4x10( 4). The observations resulted in a map of the O-2 dayglow which extends fro m 1000 to 1645 in local time and from 45 degrees S to 75 degrees N. The O-2 dayglow is formed by photolysis of high-altitude ozone, and this dayglow i s the best tracer of seasonal variations in photochemistry at low and middl e latitudes. Our observations show that O-2 dayglow can be mapped with exis ting ground-based instruments. The measured dayglow intensities display a g radual increase from 1.5 MR at 75 degrees N to 2.5 MR at 20 degrees N, a we ak minimum of 2.3 MR at the equator, and a steep increase to 5 MR at 35 deg rees-40 degrees S. The dayglow in a low-latitude belt from 5 degrees S to 2 5 degrees N (which is centered between the equator and the subsolar latitud e) is maximum at 2.5 MR near 1300 and decreases to 1.5 MR at 1000 and 1645 LT. The observed dayglow intensities are smaller than those calculated usin g the model of Clancy and Nair [1996] by a factor of approximate to 3. The observation confirms the anticorrelation between ozone and water vapor obse rved from the Viking orbiters at midsummer. Coupled with the Thermal Emissi on Spectrometer (TES) observations of temperature, dust, and water vapor, t he O-2 dayglow measurements comprise a good database to study Mars' photoch emistry and dynamics.