Upper panels: left – periodogram produced via least-squares fitting of a Fourier series to the raw lightcurve data. The most likely period solutions are 12.40971 ± 0.00005 h and 12.76236 ± 0.00006 h. Middle and right – folded lightcurves of the uncorrected data points for each of these two best-fit rotation periods. The fit in the 12.41 h case is unconvincing with various datasets not following the phase of the folded curve. The fit for the 12.76 h case is better, but can be further improved by correcting for the differing observational geometry between the various datasets. Lower left: periodogram produced via least-squares fitting of a Fourier series to the lightcurve data which has been corrected for the movement of the PAB. In this case the most likely solution was 12.76137 ± 0.00006 h. Lower right: folded lightcurve using the data corrected for the movement of the PAB vector. The scatter and phasing of the datapoints is improved, leading to a more reliable period measurement.