Zoom info: https://stanford.zoom.us/j/93437242416

We have transformed the 1.3-meter 2MASS telescope at the Whipple Observatory on Mount Hopkins, Arizona, into the Tierras Observatory: a state-of-the-art, fully-automated, ultra-precise time-series photometer. Tierrasconsistently achieves an intra-night precision of 250 ppm and night-to-night precision as low as 500 ppm for single stars over a 74-day baseline. Key design choices contributing to this precision include an expanded field of view, a custom narrow-band (40 nm) filter centered around 864 nm, and a deep-depletion, frame-transfer 4k x 4k CCD. We present the observatory's design, early results, and science program. Leveraging our night-to-night stability, we have measured previously unknown rotation periods of several M dwarfs. Additionally, our high-cadence observing mode for bright targets helped confirm the presence of a 41-day sub-Neptune in a sextuplet resonance chain around HD 110067 (K0V star) and a warm Jupiter around HD 17607 (F0 star). We are currently conducting a campaign to monitor selected stars with masses between 0.1 and 0.3 M_Sun, identified by TESS as hosting close-in planets, in order to detect longer-period terrestrial planets.