Long-term photometric monitoring of the dwarf planet (136472) Makemake

Aims. We studied the rotational properties of the dwarf planet Makemake. Methods. The photometric observations were carried out at different telescopes between 2006 and 2017. Most of the measurements were acquired in BVRI broad-band filters of a standard Johnson-Cousins photometric system. Results. We found that Makemake rotates more slowly than was previously reported. A possible lightcurve asymmetry suggests a double-peaked period of P = 22.8266 ± 0.0001 h. A small peak-to-peak lightcurve amplitude in R-filter A = 0.032 ± 0.005 mag implies an almost spherical shape or near pole-on orientation. We also measured BVRI colours and the R-filter phase-angle slope and revised the absolute magnitudes. The absolute magnitude of Makemake has remained unchanged since its discovery in 2005. No direct evidence of a newly discovered satellite was found in our photometric data; however, we discuss the possible existence of another larger satellite.