PHOTOELECTRON SPECTROMETER (PES)
                    Dr. John P. Doering

The photoelectron spectrometers on AE-C measure electron energy spectra
between 1 and 500 eV. The data written on the tape presented to the data center
consist of 6 data points every 15 seconds giving the average electron flux
observed in 6 energy intervals in units of 1/(cm**2-eV-sr-sec). The instrument
has 2 sensors and 30 operating modes (described in full detail in the 
references listed at the end of this summary). In some of these modes only
a partial sampling of the full 1-500 eV energy range is obtained, 
and consequently not all 6 words are written.
The normal energy ranges included in the 6 data words are as follows:
      Word 1  2-3 eV
      Word 2  7-9 eV
      Word 3  12-17 eV
      Word 4  25-30 eV
      Word 5  37-40 eV
      Word 6  100-500 eV
A portion of the data (acquired using the 1-500 eV, 4 times/sec, modes) has zero
values in all but Word 4 and 6.  In this case Word 4 contains the average flux
from 7-42 eV and Word 6 contains the average flux in the 100-500 eV energy
range. In all cases the data reported are a 15 sec  average of the flux for
the interval beginninq with the time associated with the data word.
   The data have been processed to remove the effects of direct entry of solar
EUV radiation into the sensors, and attenuation of the low energy (10 eV) 
signal by the spacecraft wake (see Doering et al. 1975). The data have not 
been corrected for the slight variations in spacecraft potential, a very slow
degradation in the sensitivity of the electron multipliers used, for 
interception of part of the incident flux by the spacecraft, or for the 
effects of the penetrating radiation encountered in the radiation belts 
in the South Atlantic anomaly.

    Energy time spectrograms (gray shade plots) of PES data for most of the orbits
included here are on file at the PES Research Group
                                 c/o J. P. Doering
                                 Department of Chemistry
                                 The Johns Hopkins University
                                 Baltimore, Maryland 21218


References:

Doering, J. P., C. O. Bostrom, and J. C. Armstrong, The Photoelectron-
       spectrometer Experiment on Atmosphere Explorer, Radio Science 8, 
       387 (1973).
Doering, J. P., W. K. Peterson, C. O. Bostrom, and J. C. Armstrong, 
       Measurement of Low Energy Electrons in the Day Airglow and Dayside 
       Auroral Zone from Atmosphere Explorer C, J. Geophys. Res. 80, 3934 (1975).
Doering, J. P., T. A. Potemra, C. O. Bostrom, and W. K. Peterson, Characteristic
       Energy Spectra of 1-500 eV Electrons Observed in the High Latitude 
       Ionosphere from Atmosphere Explorer C, J. Geophys. Res. 81, 5507 (1976).
Doering, J. P., W. K. Peterson, C. O. Bostrom, and T. A. Potemra, High 
       Resolution Daytime Photoelectron Energy Spectra from AE-E, Geophys. 
       Res. Lett. N3, 129 (1976).
Peterson, W. K., J. P. Doering, C. O. Bostrom,. T. A. Potemra, R. W. McEntire,
       R. A.  Hoffman, R. W. Janetzke, and J. L. Burch, Observations of 10 eV 
       to 25 keV Electrons in Steady Diffuse Aurora from Atmosphere Explorer C 
       and D, J. Geophys.Res. 82, (1977).
Peterson, W. K., J. P. Doering, T.A. Potemra, R.W. McEntire, and C. O. Bostrom,
       Conjugate Photoelectron Fluxes Observed on Atmosphere Explorer C, 
       To appear in Geophys. Res. Lett. (1977).
Potemra, T. A., W. K. Peterson, J . P . Doering, C. O. Bostrom, R. W. McEntire,
       and R. A. Hoffman, Low Energy Particle Observations in the Quiet 
       Dayside Cusp from  AE-C and AE-D.  Submitted to J. Geophys. Res.