The Geocorona photometers are designed to measure the Hydrogen Lyman-alpha emission of the neutral atmosphere. The three sensors have a field of view of 1x1 degrees and look into three different directions perpendicular to the spin axis of the satellite and tilted by +-28 degrees. They are ultraviolet photon counters with filters giving the desired bandpass. An additional O2 gas cell provides an excellent throughput of the Hydrogen radiation and simultaneously rejects the photons at 130.4 nm from excited neutral Oxygen. The temporal resolution between two complete measurements around 360 degrees is 120 s.
The GEO Characteristics are summarized below:Last update: 3 February 1999
by Harald U. Frey, nospam_hfrey@ssl.berkeley.edu