1999A&AS..140...21K

We present new R filtered CCD observations of 5 faint and moderately faint asteroids carried out between October, 1998 and January, 1999. The achieved accuracy is between 0.01-0.03mag, depending mainly on the target brightness. The obtained sinodic periods and amplitudes: 683 Lanzia - 4.6h±0.2h, 0.13mag; 725 Amanda - >3.0h, ≥0.40mag; 852 Wladilena - 4.62h±0.01h, 0.32mag (December, 1998) and 0.27mag (January, 1999); 1627 Ivar - 4.80h±0.01h, 0.77mag (December, 1998) and 0.92mag (January, 1999). The Near Earth Object 1998 PG unambiguously showed doubly-periodic lightcurve, suggesting the possibility of a relatively fast precession (P₁=1.3h, P₂=5.3h). Collecting all data from the literature, we determined new models for 3 minor planets. The resulting spin vectors and triaxial ellipsoids have been calculated by an amplitude-method. Sidereal periods and senses of rotation were calculated for two asteroids (683 and 1627) by a modified epoch-method. The results are: 683 - λ_p=15/195±25°, β_p=52±15°, a/b=1.15±0.05, b/c=1.05±0.05, P_sid=0.1964156d±0.0000001,d retrograde; 852 - λ_p=30/210±20°, β_p=30±10°, a/b=2.3±0.3, b/c=1.2±0.2; 1627 - λ_p=145/325±8°, β_p=34±6°, a/b=2.0±0.1, b/c=1.09±0.05, P_sid=0.1999154d±0.0000003,d retrograde. The obtained shape of 1627 is in good agreement with radar images by Ostro et al. (1990AJ.....99.2012O).