Definitions of the fields in the mirror databases:

mirror	The name of the mirror, composed of two characters GN, where
	G is either `h' or `p', if the mirror is a paraboloid or
	hyperpoloid, respectively, and where N is the shell number,
	one of 1, 3, 4, or 6
	
x0	The X position of the body center of the optic, in OSAC coordinates,
	in mm.

y0	The Y position of the body center of the optic, in OSAC coordinates,
	in mm.

z0	The Z position of the body center of the optic, in OSAC coordinates,
	in mm.

rho0	The radius of the body center of the optic, in mm.

p,k	OSAC conic constants

theta0	The rotation to be applied to the surface maps of the optic,
	in degrees.

az_mis	The azimuth misalignment (tilt) of the optic, in degrees.

el_mis	The elevational misalignment (tilt) of the optic, in degrees.

l	The length of the optic, in mm.

node	The position of the node.  In most cases this has been approximated
	as the midplane of the CAP.

z_f	The Z coordinate of the fore edge of the mirror, calculated as
		z_f = z0 - l / 2

z_a	The Z coordinate of the fore edge of the mirror, calculated as
		z_f = z0 + l / 2

rho_f	The radius at the fore edge of the mirror, in mm, calculated as
		rho_f = sqrt( rho0 ** 2 + 2 * k * (-l/2) - P * (-l/2)**2)

rho_a	The radius at the aft edge of the mirror, in mm, calculated as
		rho_f = sqrt( rho0 ** 2 + 2 * k * (l/2) - P * (l/2)**2)

