MASCARA-3b: A hot Jupiter transiting a bright F7 star in an aligned orbit.

We report the discovery of MASCARA-3b, a hot Jupiter orbiting its late, bright (V=8.33) F-type host every $5.55149\pm 0.00001$ days on an almost circular orbit ($e = 0.085^{+0.023}_{-0.022}$). It is the fourth exoplanet discovered with the Multi-site All-Sky CAmeRA (MASCARA), and the first of these which orbits a late-type star. Follow-up spectroscopic measurements were obtained in and outside of transit with the Hertzsprung SONG telescope. Combining the MASCARA photometry and SONG radial velocities reveals a radius and mass of $1.35\pm 0.05$ $R_{\text{Jup}}$ and $4.2\pm 0.2$ $M_{\text{Jup}}$. In addition, SONG spectroscopic transit observations were obtained on two separate nights. From analyzing the mean out of transit broadening function we obtain $v\sin i_{\star} = 20.4\pm 0.4$ km s$^{-1}$. In addition, investigating the Rossiter-McLaughlin effect, as observed in the distortion of the stellar lines directly, we find the projected obliquity to be $\lambda = 10.5\pm 24.9$ deg, consistent with alignment.