The Particle Environment Monitor (PEM) on NASA's Upper Atmosphere
Research Satellite (UARS) measures the type, amount, energy, and
distribution of charged particles injected into the Earth's
thermosphere, mesosphere, and stratosphere. PEM consists of four
instruments: the ... Atmospheric X-Ray Imaging Spectrometer (AXIS),
the High Energy Particle Spectrometer (HEPS), the Medium Energy
Spectrometer (MEPS), and the Vector Magnetometer (VMAG).
The UARS PEM level 2 AXIS1 daily product (UARPE2AXIS1) contains
the X-ray high-resolution spectral data converted to number intensity
units from the AXIS1 pixels mounted on the UARS body.
AXIS1 X-ray data covers the rough range from 2 keV to 300 keV. There
are eight AXIS1 pixels mounted in the AXIS1 housing, each viewing
different directions. The AXIS1 pixels are aligned on the spacecraft
to project about 45 deg toward the +x-axis direction from the Earthward
pointing direction (+z-axis). Each pixel of AXIS1 is staggered about
the 45 degree direction in an every-other fashion. Pixel 1 is closest
to the center line of the spacecraft and Pixel 8 is furtherest away;
however, their ground projection is dependent on the spacecraft
There is one data file per day for the PEM AXIS1 product, and the
temporal coverage is from Oct. 1, 1991 to Aug. 23, 2005. Spatial
coverage for the AXIS1 product ranges between -57 and +57 deg latitude.
The AXIS1 data files are written in network binary format. For more
information please review the PEM AXIS1 data format guide.