This total neutral density data set from the San Marco D/L satellite Drag Balance Instrument (DBI) was provided by the PI team at the Centro Ricerche Aerospaziali in Rome, Italy. It contains the 1-second DBI data for the whole San Marco mission in ASCII format on CD (originally provide on 24 floppy diskettes). Each data file (file extension .D2) contains the time and the measured total density at that time for consecutive measurements. A new file is started any time there is a data gap of more than a few seconds. A corresponding file (.D1) contains information about the exact start and stop time of the specific measurement period, about the status of all experiments and other important information for the particular orbit, e.g., the Time of the Last Maneuver; this time parameter is important to sort out dynamically perturbed periods. Two high frequency filters and a filter for the satellite spin frequency were applied to clean the density data. Regular and irregular bias patterns were computed and recorded in the D1 files.

21-second averages of these data are generated using the PI-provided software to generate orbit parameters. The data are in ASCII format and each data record includes the date, time, total density, error, altitude, latitude, longitude, and local solar time.

Further details about the San Marco spacecraft, experiment, and data sets can be found at the San Marco home page, http://crpsm.psm.uniroma1.it/