16503

At 6.9 pc comma the triple star system LTT 1445 ABC is the closest M dwarf system known to host a transiting comma terrestrial exoplanet. We have detected a second transiting planet in the system however comma the shallow transit depth comma low SNR light curves comma and placement of all three stars on one 21d_comma TESS pixel have thwarted ground-based efforts to determine which of the three stars is the host of the new planet. This is necessary in order to accurately measure the mass of either planet in the system and will be important for future JWST observations of one or both of the LTT 1445 planets. We propose to obtain HST WFC3-UVIS photometric observations in spatial scan mode of 2 transits of the newly detected planet candidate to determine which of the three stars is the host star. This confirmation can only be done with HST.