The Particle Environment Monitor (PEM) level 2 High-Energy Particle Spectrometer (HEPS) B daily product contains the electron high-resolution spectral data converted to number intensity units from the HEPS telescopes mounted on the nadir UARS boom, and the proton high-resolution spectral data converted to number intensity units from the HEPS telescopes mounted on the zenith boom.  There are no HEPS proton measuring instruments on the nadir boom.  PEM was flown on the UARS spacecraft to measure the type, amount, energy, and distribution of charged particles injected into the Earth's thermosphere, mesosphere, and stratosphere.

The PEM HEPS nadir boom electron data covers the rough range from 35 keV to 5 MeV.  There are two telescopes mounted in different directions.  These measure -165 deg and +165 deg with respect to the spacecraft -z-axis and along the spacecraft +x-axis.  The HEPS electron units accumulate a spectrum in 16.384 sec.  The PEM HEPS zenith boom proton data covers the rough range from 70 keV to 150 MeV for mounting angles less than 30 deg and 500 keV to 150 MeV for mounting angles greater than 30 deg.  There are six telescopes mounted in four different directions.  These measure -15 deg, +15 deg, +45 deg, and +90 deg with respect to the spacecraft -z-axis and along the spacecraft +x-axis.  The PEM HEPS proton units accumulate a spectrum in 16.384 sec.  The nadir HEPS electron unit in this file (labeled HEPS3) contains two telescopes (labeled telescope 1 and telescope 2).  Each telescope contains a stack of solid state crystals.  The signals from each of the crystals are combined by energy processing electronics of the instrument to yield two logical crystals or detectors, called the DE and EE detectors.  The DE detector has the rough energy range from 35 keV to 300 keV and the EE detector rough energy range is from 300 keV to 5 MeV.  These designations are used in the description of HEPS electron data.
                        
There is one data file per day for the PEM HEPSB product, and the temporal coverage is from Oct. 1, 1991 to Aug. 23, 2005. Spatial coverage for the HEPSB product ranges between -57 and +57 deg latitude.  The HEPSB data files are written in network binary format. For more information please review the PEM HEPSB data format guide.