00README.TXT CONTENTS: 00README.TXT - this file IMS_IONS_ISIS2.ASC - IMS ion densities in ASCII format Ion Mass Spectrometer (IMS) instrument: The instrument had two ion detector systems, and mass scanning through the range from 1 to 64 atomic mass units (amu) was accomplished in two sections, 1 to 8 amu and 8 to 64 amu. Two ion beams emerged from the magnetic sector of the instrument and were simultaneously detected by electron multipliers and log electrometer amplifiers. A circuit following each amplifier detected the peak amplitude of the ion current. This peak value, rather than the entire mass spectrum, was transmitted in order to reduce the required telemetry bandwidth. In this mode of operation, the complete mass range was scanned in 1 s. A backup mode was provided that produced an analog output with a sweep period of 8 s. This experiment operated nominally after launch with most of the data obtained in the peak mode and while the satellite operated in the cartwheel mode. For about 2 min per pass over Ottawa, Canada, the experiment operated in the analog mode. Inflight calibration was achieved by comparing ion concentration measurements at appropriate altitudes, i.e., where a single ion species predominated, with electron density data from the sounder on board. Other comparisons were made between the spectrometer output and measurements obtained from other related experiments on board. Format of ISIS II Bennett ion mass spectrometer data (281333 records): ------------------------------------------------ Year I4,1X yyyy Orbit I5,1X nnnnn Day of year I3,1X ddd Month I2,1X UT Day I2,1X UT Hour I2,1X UT Minute I2,1X UT Second F4.1,1X UT Gedetic latitude F6.2,1X [deg] Gedetic longitude F6.2,1X [deg] East Altitude F6.1,1X [km] Solar local time F5.2,1X [h] Magnetic local time F5.2,1X [h] Solar zenith angle F5.1,1X [deg] Diplat F6.2,1X [deg] McIlwain L param. F7.2,1X B F5.1,1X [100*nT] F107 flux F5.1,1X [10^-22 W/m^2/Hz] Kp index I2,1X 3*Kp (e.g. 0+ = 1) Dst index I4,1X ////////////////////density///////////////////// --------------lower range (1-8 AMU) ----------------------- log10(n(H+)) F7.4,1X [m-3] log10(n(D+)) F7.4,1X [m-3] log10(n(He)) F7.4,1X [m-3] log10(n(N++)) F7.4,1X [m-3] log10(n(O++)) F7.4,1X [m-3] -------------upper range (8-64 AMU) ------------------------ log10(n(O++)) F7.4,1X [m-3] log10(n(N+)) F7.4,1X [m-3] log10(n(O+)) F7.4,1X [m-3] log10(n(18+)) F7.4,1X [m-3] log10(n(N2+)) F7.4,1X [m-3] log10(n(NO+)) F7.4,1X [m-3] log10(n(O2+)) F7.4,1X [m-3] //////////////time difference dt (from UT)///////// --------------lower range----------------------- dt(H+) F5.1,1X [s] UT(H+) = UT + dt(H+) dt(D+) F5.1,1X [s] UT(D+) = UT + dt(D+) dt(He+) F5.1,1X [s] UT(He+) = UT + dt(He+) dt(N++) F5.1,1X [s] UT(N++) = UT + dt(N++) dt(O++) F5.1,1X [s] UT(O++) = UT + dt(O++) -------------upper range------------------------ dt(O++) F5.1,1X [s] UT(O++) = UT + dt(O++) dt(N+) F5.1,1X [s] UT(N+) = UT + dt(N+) dt(O+) F5.1,1X [s] UT(O+) = UT + dt(O+) dt(18+) F5.1,1X [s] UT(18+) = UT + dt(18+) dt(N2+) F5.1,1X [s] UT(N2+) = UT + dt(N2+) dt(NO+) F5.1,1X [s] UT(NO+) = UT + dt(NO+) dt(O2+) F5.1,1X [s] UT(O2+) = UT + dt(O2+) ------------------------------------------------ Data contact: Dieter.Bilitza-1@nasa.gov> NASA Official: Dr. Robert McGuire