Preliminary Results of Studies of the Opposition Effect Using the JPL Long-Arm Photopolarimeter Hapke, B. W. ; Nelson, R. M. ; Smythe, W. D. ; Horn, L. J. ; Herrera, P. ; Gharakanian, V. Abstract Publication: AAS/Division for Planetary Sciences Meeting Abstracts #26 Pub Date: June 1994 Bibcode: 1994DPS....26.1206H