Ultra-Stable Temperature And Pressure Control For The Habitable Zone Planet Finder Spectrograph

We present recent long-term stability test results of the cryogenic Environmental Control System (ECS) for the Habitable zone Planet Finder (HPF), a near infrared ultra-stable spectrograph operating at 180 Kelvin. Exquisite temperature and pressure stability is required for high precision radial velocity (< 1 m/s) instruments, as temperature and pressure variations can easily induce instrumental drifts of several tens-to-hundreds of meters per second. Here we present the results from long-term stability tests performed at the 180 K operating temperature of HPF, demonstrating that the HPF ECS is stable at the 0.6 mK level over 15-days, and < 10(-7) Torr over months.