Changes for Version 2.0 CHAMP Density:
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1. Interpolation of satellite attitude data improved
	a. methods updated to handle missing data
	b. index (NumInterp variable) added to data set indicating any interpolation of attitude data
2. Accelerometer instrument biases reprocessed and smoothed
3. Coefficient of drag updated from method of Cook [1965] to Sentman [1961]
	a. includes more realistic formulation of the coefficient of drag
	b. includes the effect of 'thermal drag', a phenomenon that increases the coefficient of drag for long satellites
	c. Variable 'Cd' added
4. Variable 'LatBin' added and 'Lat' modified
	a. LatBin gives the center of the current averaging bin
	b. Lat gives the mean position of the satellite at data points within the current averaging bin
	c. This ensures that the satellite position (defined by variables Lat, Lon, and Height) is consistent
5. NRL-MSIS model density is given at each time and satellite position
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Changes for Version 2.1 CHAMP Density:
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1. Addition of Quasi-Dipole Latitude (Mlat), Magnetic Longitude (Mlon), and Magnetic Local Time (Mlt)
	See:	Richmond, A. D. (1995), Ionospheric Electrodynamics Using Magnetic Apex Coordinates,
			J. Geomag. Geoelectr., 47(2), 191-212.