Lightcurves of Centaurs 2000 QC(243) and 2001 PT13

We present CCD photometric observations of Centaurs 2000 QC(243) and 2001 PT13. For 2000 QC(243), a large amplitude period is found at 4.57 h +/- 0.05 h, which likely corresponds to half the rotation period of the body, or coincides with the full rotation period, depending on whether the variability is induced by an irregular shape or by albedo features. The apparent double-peaked lightcurve favors the first interpretation. The large amplitude of the oscillations imply a very irregular shape for this object or a large albedo assymmetry between the two hemispheres. For 2001 PT13, a clear period of 4.15 h +/- 0.05 h was detected, with an amplitude of 0.16 mag. Since 4.15 h is close to the breakup limit for typical cometary densities and tensile strengths, 8.3 h appears to be a more likely rotation period.