I study type Ia supernovae. With good measurements, these supernovae can be used as “standard candles,” so that measuring their apparent brightness gives their distances. These distances are probes of the expansion history of the universe and the objects themselves are astrophysically important.

Using these supernovae for cosmology requires many careful steps, from the search, to detailed pixel-level models of the images for accurate photometry (brightness measurements), to statistical techniques for the accurate estimation of uncertainties.

The SUbaru Supernovae with Hubble Infrared (SUSHI) HST program (co-PI’d with Nao Suzuki) is currently collecting IR data on high-redshift SNe discovered in the Subaru Strategic Program.

When possible, I perform my studies using “blinded analyses,” which help protect researchers from inadvertently tweaking their analysis steps until they obtain their expected results.

I am also the cofounder and now the overseer of the Union compilations of SNe Ia. These can be found at