ASTEROID OBSERVATIONS AT LOW PHASE ANGLES - I - 50-VIRGINIA, 91-AEGINA AND 102-MIRIAM

We present observations of magnitude-phase dependences of three low-al bedo asteroids down to phase angles of 0.1-0.2 degrees. Data were obta ined during 40 nights from 1994 to 1995 within the joint observational program at ESO and Kharkiv Astronomical Observatories with the aim to reach as low phase angles as possible. All three low-albedo asteroids may display a small nonlinear increase in magnitude-phase dependence at subdegree phase angles. The phase curves of 50 Virginia and 102 Mir iam are poorly approximated by the HG function. Rotation periods of th e asteroids were also determined: 14.310+/-0.010 hours for 50 Virginia , 6.030+/-0.001 h for 91 Aegina and 15.789+/-0.003 h for 102 Miriam. ( C) 1998 Elsevier Science Ltd. All rights reserved.