Help for PHOTFIT2_VEVERKA


PURPOSE:

In this PDF, the user is asked for the only parameters and there absolute 
limits needed to fit Veverka's photometric function.
If a sulution guess falls out-of-bonds then the attemp will be aborted and 
a new guess attempted.

MATHEMATICAL BACKGROUND :

Exept close to zero phase, this expression is a good description of light 
scattered by low-albedo bodies of the solar system, such as the Moon and 
Mercury, for which only light that has been scattered once contributes 
significantly to the brightnes.

bidirectional reflectance [1/str] :

r(i,e,g) = ( cos(i) / (cos(e)+cos(e)) )  
	 * (A_VEVERKA + B_VEVERKA * phase + C_VEVERKA * exp(-DVEVERKA * phase))

usually :
C_VEVERKA=1-A_VEVERKA


REFERENCE :
Joseph Veverka, J. Goguen, S. Young, J. Elliont, Scattering of light from 
particulate surfaces. 
I. A laboratory assessment of multiple-scattering effects.
Icarus, Vol. 34, p. 406-414


PROGRAMMER:

Friedel Oschuetz
Institute of Planetary Exploration
DLR
12484 Berlin (FRG)