Transformation from IAU 1958 Galactic coordinates to De Vaucouleurs supergalactic coordinates. (double precision)
dl,db double Galactic longitude and latitude l2,b2
*dsl,*dsb double Supergalactic longitude and latitude (all arguments are radians)
slaDcs2c, slaDimxv, slaDcc2s, slaDranrm, slaDrange
De Vaucouleurs, De Vaucouleurs, & Corwin, Second reference catalogue of bright galaxies, U. Texas, page 8. Systems & Applied Sciences Corp., Documentation for the machine-readable version of the above catalogue, contract NAS 5-26490. (These two references give different values for the Galactic longitude of the Supergalactic origin. Both are wrong; the correct value is l2 = 137.37.) P.T.Wallace Starlink 8 December 1993