WASP-169, WASP-171, WASP-175 and WASP-182: three hot Jupiters and one bloated sub-Saturn mass planet discovered by WASP-south

We present the discovery of four new giant planets from WASP, three hot Jupiters and one bloated sub-Saturn mass planet; WASP-169b, WASP-171b, WASP-175b and WASP-182b. Besides the discovery photometry from wasp we use radial velocity measurements from CORALIE and HARPS as well as follow-up photometry from EulerCam, TRAPPIST-North and -South and SPECULOOS. WASP-169b is a low density Jupiter ($M=0.561 pm 0.061~mathrm{M_{Jup}}, R=1.304^{+0.150}_{-0.073} ~mathrm{R_{Jup}}$) orbiting a V=12.17 F8 sub-giant in a 5.611~day orbit. WASP-171b is a typical hot Jupiter ($M=1.084 pm 0.094~mathrm{M_{Jup}}, R=0.98^{+0.07}_{-0.04} ~mathrm{R_{Jup}}$, $P=3.82~mathrm{days}$) around a V=13.05 G0 star. We find a linear drift in the radial velocities of WASP-171 spanning 3.5 years, indicating the possibility of an additional outer planet or stellar companion. WASP-175b is an inflated hot Jupiter ($M=0.99 pm 0.13~mathrm{M_{Jup}}, R=1.208 pm 0.081 ~mathrm{R_{Jup}}$, $P=3.07~mathrm{days}$) around a V=12.04 F7 star, which possibly is part of a binary system with a star 7.9arcsec away. WASP-182b is a bloated sub-Saturn mass planet ($M=0.148 pm 0.011~mathrm{M_{Jup}}, R=0.850pm 0.030 ~mathrm{R_{Jup}}$) around a metal rich V=11.98 G5 star ([Fe/H]$=0.27 pm 0.11$). With a orbital period of $P=3.377~mathrm{days}$, it sits right in the apex of the sub-Jovian desert, bordering the upper- and lower edge of the desert in both the mass-period and radius-period plane. WASP-169b, WASP-175b and WASP-182b are promising targets for atmospheric characterisation through transmission spectroscopy, with expected transmission signals of 121, 150 and 264 ppm respectively.