NASA Planetary Data System, MicroWave Sub-Node

Mission:      Venera 15/16
Phase:        Mapping
Instrument:   Microwave Radiometer
Dataset:      Venera Radiometer Measurements
Origin:       Moscow Power Institute
Cognizant:    Levchenko (for Acad. Bogomolov)
Size:         5.8 Mbytes (original), 2.1 Mbytes (compressed)
Format:       BINARY
Prepared by:  Peter G. Ford

Data file "mpi-venus-alt.dat" contains radiometry measurements made
by both spacecraft. 

File Format:

  The file contains lines of ASCII characters in the following format:

	mm dd nn xxxxx yyyyy xxx.xxx yy.yyy vvv hhh aa.aa

          mm - month of spacecraft periapsis
          dd - day of spacecraft periapsis
          nn - spacecraft ID (15 or 16)
       xxxxx - x-coordinate of antenna boresight
       yyyyy - y-coordinate of antenna boresight
      xx.xxx - latitude of antenna boresight (deg)
    yyyy.yyy - longitude of antenna boresight (deg)
         vvv - brightness temperature (K), vertical polarization
         hhh - brightness temperature (K), horizontal polarization
       aa.aa - incidence angle

  Each line contains 49 characters. The xxxxx and yyyyy fields
  represent the boresight coordinates in a polar stereographic
  projection, related to latitude and longitude as follows:

	lon = atan2(-xxxxx, yyyyy)
	lat = asin((a*a-yyyy*yyyy)/(a*a+yyyy*yyyy))
  where
	a = 8192*cos(lon)

Coordinate System:

  Venera latitudes and longitudes are expressed in the IAU (1982)
  approved coordinate system (Davies, M.E. et al, "Report of the IAU
  Working Group on Cartographic Coordinates and Rotational Elements
  of the Planets and Satellites: 1982"; Celestial Mechanics, Vol.
  29, 1983, p. 309-321).

  The following equation transforms the Venera coordinate system into
  the "VBF85" system used by Magellan:

    /x\         / 0.999997087 -0.002380124 -0.000398768 \   /x\
    |y|       = | 0.002379790  0.999996819 -0.000836184 | * |y|
    \z/VBF85    \ 0.000400757  0.000835233  0.999999571 /   \z/Venera