Asteroid observations at low phase angles. I. 50 Virginia, 91 Aegina and 102 Miriam

Kurzfassung

We present observations of magnitude-phase dependences of three low-albedo asteroids down to phase angles of 0.1 - 0.2 degrees. Data were obtained during 40 nights in 1994-1996 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 Miriam are poorly approximated by the HG function. Rotation periods of the asteroids were also determined: 14.21 +/- 0.010 hours for 50 Virginia, 6.030 +/- 0.001 hours for 91 Aegina and 15.789 +/- hours for 102 Miriam.