| definition |
- The Visible Airglow Experiment (VAE) on Atmosphere Explorers
C, -D and -E (AE-C, -D, -E) is an airglow photometer designed to
measure various thermospherlc emission features during the day and
night both at low latitudes and in auroras. The photometer has two
distinct optical channels, a high sensitlvity channel (channel 2)
with a large field of view (3 degrees half angle cone) and a low sensitivity
channel (channel 1) with a narrow field of view (3/4 degree half angle cone)
to resolve small airglow features. The system is protected by a combination
100 to 1 attenuating system and a cathode back biasing scheme
which allows measurements of maximum sensitivity within a fraction of
a second of viewing the bright limb of the earth.
The experimental design allows six atmospheric emissions from
the near ultraviolet to the near infrared to be monitored regularly on
each satellite. The six filters are mounted on a wheel along with a
dark position and calibrate position. The calibration source is made
of phosphor and is activated by radioactive promethium. Each optical
system employs a combination of a simple objective lens and field stop
to define the angular field of view. The integration periods for
channels 1 and 2 are 32 and 120 msec, respectively.
[Source: NASA]
|
