Lightcurve and Rotation Period of The Slow Rotator 12867 Joeloic

Minor planet 12867 Joeloic was estimated to have a long rotation period based on measurements during its 2016 opposition. To solve this period, we monitored the asteroid for five months during the 2023 opposition. A total of 3,708 measurements taken over 134 sessions made it possible to find a more reliable rotation period at 426.2 h ± 0.4h, with a lightcurve amplitude of 0.53 ± 0.03 mag. The non-repetitiveness of the curve during the nine full periods led to suspicion that 12867 could be a tumbling object. This was confirmed by Dr. Petr Pravec, who assessed that 12867 is a tumbling object of PAR = -2 (secure tumbler but with and unresolved second period).