Data Set Overview : All PROFILE data are packaged by periapsis number for each aerobraking orbit. PROFILE data are provided at one second resolution in a table labeled Pyyy.tab where 'yyy' is the three digit periapsis number.   Parameters : Time from periapsis: Units : seconds Latitude: Units : degrees Longitude: Units : degrees Local Solar Time: Units : hours Solar Zenith Angle: Units : degrees Altitude for 1-sec. data: Units : km Density, 1 sec.: Units : kg/km**3 Sigma 1 sec. density: Units : kg/km**3 Altitude for 39-sec. data: Units : km Density, 39 sec.: Units : kg/km**3 Sigma 39 sec. density: Units : kg/km**3   Data : For each orbit, PROFILE data consist of an n-by-11 array in the file Pyyy, where n is the number of seconds of data received during the aerobraking pass. Column 1 contains the time from periapsis. Columns 2 through 11 contain Latitude, Longitude, Local Solar Time, Solar Zenith Angle, Altitude for 1 Second Density, 1 Second Density, Sigma for 1 Second Density, Altitude for 39 Second Density, 39 sec. Density and Sigma for 39 Second Density.   Processing : Accelerometer data were processed in the PROFILE stage through several steps and the entire process with examples is given in [TOLSONETAL2007] First, traditional Euler terms were removed body angular rates. During operations,no attempt was made to synchronize data or to remove the effects of thruster firings. Because of the considerable wave structure in the density data, which do not represent the 'mean' thermosphere, a second data set is also archived. A 39 point running mean of the 1 second density is the final data product. Data are included for only those times following the final negative 1 sec. density inbound, and prior to the first negative density value outbound. These negative densities values arise due to the offsets and biases of the system at small accelerations.   Coordinate System : Latitude and longitude are in the IAU Mars Centered Mars Equatorial System. Altitude is above the IAU reference ellipsoid, with a:3396.19 km and f:0.005886.

Confidence Level Overview : Standard deviations on 1 sec. densities are based on the local noise on the data as determined by a seven point running mean. Standard deviations on the 39 sec. data are based on the square root of n law.   Review : Version 1 products are based on operational data sets which underwent orbit to orbit comparisons with navigation team and spacecraft team results, see TOLSONETAL2007.   Data Coverage and Quality : Data coverage during an aerobraking pass varied throughout the mission. The nominal pass assured that sufficient data were recovered above 250 km to calibrate the accelerometers both inbound and outbound.