Page "90482 Orcus" Paragraph 6

The rotation period of the primary is not known.

Different photometric surveys have produced different results.

Some show low amplitude variations with periods ranging from 7 to 21 hours, while others show no variability.

However the value obtained by Ortiz et al., about 10. 5 hours seems to be the most likely.

The rotational poles of Orcus probably coincide with the orbital poles of its moon, Vanth.

This means that Orcus is currently viewed pole-on, which could explain the near absence of any rotational modulation of its brightness.

If, however, the primary is tidally locked with the satellite, the rotational period will coincide with the 9. 7-day orbital period of Vanth.