This experiment contained a filter photometer designed to measure various airglow and auroral
features in the spectral range between 3000 and 7500 A. The primary information obtained from this experiment
was the rates of excitation of the atomic and molecular constituents of the thermosphere. For the AE-C mission,
the following six specific lines and bands were chosen for study since they play an important role in the
photochemical energy balance of the atmosphere (expressed in Angstroms): 3371, 4278, 5200, 5577, 6300, and 7319.
The emissions were measured in pairs: 5577 and 6300, 7319 and calibration, 3371 and 5577, 5200 and 7319, 4278
and 3371, calibration and 5200, and 6300 and 4278. Two optical systems viewed at right angles to each other.
Each one employed a combination of a simple objective lens and field stop to define the field of view, and
each contained a multistage light baffle. The wide-angle high-sensitivity system (designated channel 2) had
a field of view of 3 deg half-angle, and was used to measure the nightglow, dayglow above the satellite, and
other weak emission features. The less sensitive system (designated channel 1) had a field of view of
approximately 3/4 deg half-angle and was used for dayglow and nightglow horizon measurements, as well as
discrete auroral features which showed strong spatial gradients. Both optical channels had a diameter of 2.2 cm.
They shared a filter wheel that contained six interference filters at the wavelengths identified above, and
two other positions. One was a dark position for noise measurements, and the other was a calibrate position.
The dynamic range of the instrument was 1.E16 photons per s sq m (1.E6 rayleighs). In order that the sensors
would respond in a fraction of a second to large changes in surface brightness without any noticeable enhancement
in the background count rate, each one contained a 1/100 attenuator and an electronic circuit to back-bias
the cathode. With these protective features it was possible to measure a dark feature with no apparent enhancement
in background within 120 ms after a direct view of the sun. Photons reaching the cathode were recorded using a
pulse-counting system. For more experiment details, see P. B. Hays et al., Radio Sci., v. 8, n. 4, p. 369, 1973.
NSSDC has all the useful data that exist from this investigation.