A Novel Circumbinary Planet Detection Technique Reveals TIC 172900988b

We discuss TIC 172900988 b, the first transiting circumbinary planet to be detected via the "1-2 punch technique", where two transits occur (one over the primary star and one over the secondary star) during one conjunction pass. The previously unknown binary consists of a pair of 3.5 Gyr-old, 1.2 M_Sun stars in a moderately eccentric 20-day orbit. By combining TESS observations with archival photometry of the stellar eclipses, an unambiguous signature of apsidal precession of the binary is seen, thus allowing the mass of the planet to be estimated: 2.6-3.1 M_Jup. The planet's radius is well-constrained by the transits to be 1.0 R_Jup, however its orbital period remains elusive, though in the range ~189-204 days. We will present updated planet parameters that employ new observations. As one of the brighter systems (V=10.14 mag) and with relatively deep transits (~ 0.3%), the system could be a benchmark circumbinary planet.