Astron. Astrophys. Suppl. Ser. 140, 21-28

CCD photometry and new models of 5 minor planets

L.L. Kiss^1,3 - Gy. Szabó^1,3 - K. Sárneczky^2,3

Send offprint request: l.kiss@physx.u-szeged.hu

1 - Department of Experimental Physics & Astronomical Observatory, JATE University, H-6720 Szeged, Dóm tér 9., Hungary
2 - Department of Physical Geography, ELTE University, H-1088 Budapest, Ludovika tér 2., Hungary
3 - Guest Observer at Konkoly Observatory, Hungary

Received June 28; accepted September 6, 1999

Abstract:

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 0.01-0.03 mag, depending mainly on the target brightness. The obtained sinodic periods and amplitudes: 683 Lanzia - $4\hbox{$.\!\!^{\rm h}$ }6\pm0\hbox{$.\!\!^{\rm h}$ }2$, 0.13 mag; 725 Amanda - $>3\hbox{$.\!\!^{\rm h}$ }0$, $\geq$0.40 mag; 852 Wladilena - $4\hbox{$.\!\!^{\rm h}$ }62\pm0\hbox{$.\!\!^{\rm h}$ }01$, 0.32 mag (December, 1998) and 0.27 mag (January, 1999); 1627 Ivar - $4\hbox{$.\!\!^{\rm h}$ }80\pm0\hbox{$.\!\!^{\rm h}$ }01$, 0.77 mag (December, 1998) and 0.92 mag (January, 1999). The Near Earth Object 1998 PG unambiguously showed doubly-periodic lightcurve, suggesting the possibility of a relatively fast precession ( $P_1=1\hbox{$.\!\!^{\rm h}$ }3$, $P_2=5\hbox{$.\!\!^{\rm h}$ }3$).

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: $683 - \lambda_{\rm p}=15/195\pm25^\circ$, $\beta_{\rm p}=52\pm15^\circ$, $a/b=1.15\pm0.05$, $b/c=1.05\pm0.05$, $P_{{\rm sid}}$ = 0 $.\!\!^{\rm d}$1964156 $\pm$ 0 $.\!\!^{\rm d}$0000001, retrograde; $852 - \lambda_{\rm p}=30/210~\pm~20^\circ$, $\beta_{\rm p}=30~\pm~10^\circ$, $a/b=2.3~\pm~0.3$, $b/c=1.2~\pm~0.2$; $1627 - \lambda_{\rm p}=145/325~\pm~8^\circ$, $\beta_{\rm p}=34~\pm~6^\circ$, $a/b=2.0~\pm~0.1$, $b/c=1.09~\pm~0.05$, $P_{{\rm sid}}$ = 0 $.\!\!^{\rm d}$1999154 $\pm$ 0 $.\!\!^{\rm d}$0000003, retrograde. The obtained shape of 1627 is in good agreement with radar images by Ostro et al. (1990).

Key words: solar system: general minor planets