HIRAX: A Novel Multiband Photometer for Ground-based Characterization of Hot Jupiter Atmospheres

The atmospheres of exoplanets provide a unique probe to studying the chemical diversity of exoplanet systems. Established observing techniques like transmission spectroscopy can provide information about the atmospheric spectrum, which can be better constrained using a combination of both high and low resolution data. Low resolution transmission spectroscopy efforts have produced many interesting results but largely rely on pre-existing instruments that are limited in the photometric precision that can be achieved over the duration of an exoplanet transit. Here I present the High-efficiency Instrument for the Rapid Assessment of eXo-atmospheres (HIRAX) that offers a different approach to performing transmission spectroscopy by using multiple narrowband filters to simultaneously image an exoplanet transit in multiple 3Å bandpasses. The high throughput of HIRAX and its imaging-based design is expected to offer an efficient path towards a survey of alkali lines in hot Jupiter atmospheres. A three bandpass version of HIRAX was recently funded and work is underway to optimize the instrument design for transmission spectroscopy of the sodium doublet (5889.9Å and 5895.9Å) to test on the Hale telescope at Palomar. In this presentation, I will discuss the motivation for HIRAX, the current instrument design, challenges, and on-sky testing plans.