Dynamics Explorer-1 (DE 1) Spin-Scan Auroral Imager (SAI) Data

This directory contains GIF images from the binary data for the SAI instrument that flew on the DE 1
spacecraft which was launched on 3 August 1981 into an elliptical orbit with
an altitude range of 570 km to 23 000 km (3.63 Earth radii) and its 
operations ceased in January 1991.

The Dynamics Explorer-1 Spin-Scan Auroral Imager (DESAI) Images from
the Vacuum-UltraViolet photometer are cataloged here for 1981 to 1991 by
year, day-of-year (DOY), and filter.

Processed images from the mission analysis files, and originally hosted at
http://www-pi.physics.uiowa.edu/sai-data/images

Pulled into SPDF holdings 2021May24 by Robert.M.Candey@nasa.gov

FILE_NAMING_CONVENTION:
    The naming convention describes the contents of the image files, as follows:
         de1_sai_plot-F_FFFF_YYYYDDDTHHMMSS_P.GIF
ex:      de1_sai_plot-2_123W_1981266T190216_C.GIF

where characters:
         E = 
         F_FFFF = filter as in table below
         YYYY = year
         DDD  = day of year
         HHMMSS = UT as hour, minute, second
         P   = photometer ID (A,B,C)


DESAI Photometer C
Vacuum-UltraViolet Filters
The third imaging photometer is equipped with filters and a photocathode for observations 
at vacuum-ultraviolet wavelengths, in particular emissions of the Lyman-Birge-Hopfield 
band of molecular nitrogen at about 140 to 170 nm. 

Imaging at these wavelengths allows coverage of the auroral oval in both the dark and sunlit ionospheres. 
The filter array for the vacuum-ultraviolet imaging photometer also includes filters 
for atomic hydrogen Lyman alpha at 121.6 nm and oxygen lines at 130.4 and 135.6 nm.

Filters included in this dataset for observations of the aurora and geocorona are the shown in the following table.
	    VACUUM-ULTRAVIOLET IMAGING PHOTOMETER C
Filter#  Name   Lp,nm   dL,nm    Tp     Sp    S(Lya)    Principal function
-------  ----   ------  -----   ----   ----   ------   ------------------------
   1     136W     150     43    0.21   1.65            N2(LBH) band
   2     123W     131     32    0.30   3.08            OI lines
   3     120W     125     30    0.36   3.10    2.18    H Lya line
   4     140N     156     34    0.18   1.27            N2(LBH) band (narrow dL)
   5     136W     150     41    0.25   2.05            N2(LBH) band
   7     123W     128     30    0.30   3.08            OI lines
   B     117N     120     11    0.14   0.91    0.79    H Lya line (narrow dL)
   C     117A     130     47    1.00   10.5    7.0     H Lya line

Lp is wavelength of peak transmission for filter.
dL is passband FWHM.
Tp is transmission at Lp and +15 deg C.
Sp is sensitivity at Lp in units of counts/(kilorayleigh-pixel).
S(Lya) is sensitivity at L121.6 in units of counts/(kilorayleigh-pixel).


Not used:
         14   = filter number (1-9,A,B,C)
         15   = mirror range (F:full,R:restricted,O:stepping off).