New spin period determination for comet 6P/dArrest

A lightcurve of comet 6P/dʹArrest from R-band CCD images taken at La Palma 2.52 m NOT telescope is presented. The lightcurve shows noticeable periodic changes in brightness produced by rotational modulation. The periodogram analysis of the lightcurve shows a peak with a confidence level exceeding 99.9% at 3.336 h. Assuming an elongated nucleus, the most likely spin period is therefore 6.67 +-0.03 h, but other periodicities are also possible. The peak to peak amplitude is 0.082 +-0.016 mag. This period, and the other peaks detected in the periodogram, are not commensurable with previous estimates of the spin period of comet 6P/dʹArrest. If all the measurements are correct, the differences between this estimate and the previous ones could be due to a possible change in the spin period of comet 6P/dʹArrest or to this comet being rotating in a complex mode.