%AEisner, N%ANicholson, B%ABarragán, O%AAigrain, S%ALintott, C%AKaye, L%AKlein, B%AMiller, G%ATaylor, J%AZicher, N%ABuchhave, L%ACaldwell, D%AHorner, J%ALlama, J%AMortier, A%ARajpaul, V%AStassun, K%ASporer, A%ATkachenko, A%AJenkins, J%ALatham, D%ARicker, G%ASeager, S%AWinn, J%AAlhassan, S%ABaeten, E%ABean, S%ABundy, D%AEfremov, V%AFerstenou, R%AGoodwin, B%AHof, M%AHoffman, T%AHubert, A%ALau, L%ALee, S%AMaetschke, D%APeltsch, K%ARubio-Alfaro, C%AWilson, G%Anull Ed.%BJournal Name: Monthly Notices of the Royal Astronomical Society; Journal Volume: 505; Journal Issue: 2 %D2021%I %JJournal Name: Monthly Notices of the Royal Astronomical Society; Journal Volume: 505; Journal Issue: 2 %K %MOSTI ID: 10277306 %PMedium: X %TPlanet Hunters TESS III: two transiting planets around the bright G dwarf HD 152843 %XABSTRACT We report on the discovery and validation of a two-planet system around a bright (V  = 8.85 mag) early G dwarf (1.43  R⊙, 1.15  M⊙, TOI 2319) using data from NASA’s Transiting Exoplanet Survey Satellite (TESS). Three transit events from two planets were detected by citizen scientists in the month-long TESS light curve (sector 25), as part of the Planet Hunters TESS project. Modelling of the transits yields an orbital period of $11.6264 _{ - 0.0025 } ^ { + 0.0022 }$ d and radius of $3.41 _{ - 0.12 } ^ { + 0.14 }$ R⊕ for the inner planet, and a period in the range 19.26–35 d and a radius of $5.83 _{ - 0.14 } ^ { + 0.14 }$ R⊕ for the outer planet, which was only seen to transit once. Each signal was independently statistically validated, taking into consideration the TESS light curve as well as the ground-based spectroscopic follow-up observations. Radial velocities from HARPS-N and EXPRES yield a tentative detection of planet b, whose mass we estimate to be $11.56 _{ - 6.14 } ^ { + 6.58 }$ M⊕, and allow us to place an upper limit of 27.5 M⊕ (99 per cent confidence) on the mass of planet c. Due to the brightness of the host star and the strong likelihood of an extended H/He atmosphere on both planets, this system offers excellent prospects for atmospheric characterization and comparative planetology. %0Journal Article