BURTOVOI, ALEKSANDRALEKSANDRBURTOVOIZAMPIERI, LucaLucaZAMPIERIFIORI, MicheleMicheleFIORINaletto, GiampieroGiampieroNalettoSPOLON, ALESSIAALESSIASPOLONBarbieri, CesareCesareBarbieriPAPITTO, ALESSANDROALESSANDROPAPITTOAMBROSINO, FilippoFilippoAMBROSINO2022-03-292022-03-2920201745-3925http://hdl.handle.net/20.500.12386/32000We present a timing analysis of the transitional millisecond pulsar PSR J1023+0038 using observations taken between January 2018 and January 2020 with the high time resolution photon counter Aqueye+ mounted at the 1.82 m Copernicus telescope in Asiago. We report the first measurement of the timing solution and the frequency derivative of PSR J1023+0038 based entirely on optical data. The spin-down rate of the pulsar is ( - 2.53 ± 0.04) × 10<SUP>-15</SUP> Hz<SUP>2</SUP>, which is ∼20% slower than that measured from the X-ray observations taken in 2013-2016 and ∼5% faster than that measured in the radio band during the rotation-powered state.STAMPAenArticle10.1093/mnrasl/slaa1332-s2.0-85096882484http://arxiv.org/abs/2007.09980v1https://academic.oup.com/mnrasl/article/498/1/L98/5875926?login=true2020MNRAS.498L..98BFIS/05 - ASTRONOMIA E ASTROFISICA