The Particle Environment Monitor (PEM) Level 3AT data product consists of daily, 65.536 second interval time-ordered, vertical profiles of electron, proton and x-ray energy deposition rates. PEM was made up 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).  PEM was flown on NASA's Upper Atmosphere Research Satellite (UARS) to measure the type, amount, energy, and distribution of charged particles injected into the Earth's thermosphere, mesosphere, and stratosphere.  PEM x-ray data are processed with the version 3 algorithm, and the electron and proton data are version 4.

The PEM level 3AT data consist of 18 granules per day.  A data granule is defined as one PEM subtype per day.  The following subtypes are available:
      
 1. EDEP3AT_P01  - x-ray pixel 01 energy deposition
 2. EDEP3AT_P02  - x-ray pixel 02 energy deposition
 3. EDEP3AT_P03  - x-ray pixel 03 energy deposition
 4. EDEP3AT_P04  - x-ray pixel 04 energy deposition
 5. EDEP3AT_P05  - x-ray pixel 05 energy deposition
 6. EDEP3AT_P06  - x-ray pixel 06 energy deposition
 7. EDEP3AT_P07  - x-ray pixel 07 energy deposition
 8. EDEP3AT_P08  - x-ray pixel 08 energy deposition
 9. EDEP3AT_P09  - x-ray pixel 09 energy deposition
10. EDEP3AT_P10  - x-ray pixel 10 energy deposition
11. EDEP3AT_P11  - x-ray pixel 11 energy deposition
12. EDEP3AT_P12  - x-ray pixel 12 energy deposition
13. EDEP3AT_P13  - x-ray pixel 13 energy deposition
14. EDEP3AT_P14  - x-ray pixel 14 energy deposition
15. EDEP3AT_P15  - x-ray pixel 15 energy deposition
16. EDEP3AT_P16  - x-ray pixel 16 energy deposition
17. EDEP3AT_ELEC - electron energy deposition
18. EDEP3AT_PROT - proton energy deposition
   
The x-ray pixel subtypes are grouped together in a single tar file for each day, the electron and proton are available as individual files per day.  The units for energy deposition rate are in [erg/cm**3/sec].  The PEM data are on the UARS standard altitude levels (in km) given by:

z(i) = 5 * i,                i <= 12
z(i) = 60 + (i - 12) * 3,    13 <= i <= 32
z(i) = 120 + (i - 32) * 10,  33 <= i <= 50
      
The data files are available in a binary record oriented format.