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P. Rousselot, J-M. Petit (Observatoire de Besancon), F. Poulet (Institut d'Astrophysique Spatiale, Orsay)
We present photometric data obtained on the Kuiper Belt Object 1999 TD10 and the Centaur 2000 EC98. The goal of these observations is to derive their phase function, as well as their rotational lightcurve.
We managed to observe 1999 TD10 in the R, V and B bands during six different nights in October-November-December 2001 period at the Danish 1.54-m telescope of ESO in Chile. The Sierra Nevada Observatory 1.50-m telescope was also used in order to add relative magnitudes to improve the determination of the rotational lightcurve. The observations are compatible with a single-peaked rotational lightcurve with a 7h41.5mn±0.1mn period or a double-peaked lightcurve with a 15h22.9mn±0.1mn. We present the phase curve obtained when assuming that the lightcurve is single-peaked. This phase curve reveals clearly an increase of about 0.3 magnitude and of similar importance for the three bands when phase angle decreases from 3.7 deg to 0.3 deg. The brightness increases linearly with decreasing phase angle and thus prevents modelling of the opposition surge. Neverthless the poor sample of the observational data does not permit a firm conclusion concerning the presence or absence of an opposition surge on the phase angle range covered by our data. Complementary observations are needed.
We managed to observe 2000 EC98 during four half nights in March 2002 with the Danish telescope and three consecutive nights with the ESO 3.6-m telescope in April 2003. So far we have only preliminary results concerning the rotational period of this object. If a single-peaked lightcurve is assumed we find a period of 12h56mn±6mn and a peak to peak amplitude (in the R band) of 0.28±0.03 magnitude.
We compare also these results to the other one already published. They are in good agreement, expecially for the slope of the phase function curve, which is equal to 0.121±0.003 mag.deg-1 for 1999 TD10 and for the phase angle range covered by our observations.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.