My research in the past few years has been focused on the evolution and formation of galaxies. I have investigated this problem up to z=7 typically using deep Hubble Space Telescope Data. In the past, I led the GOODS NICMOS Survey as well as a large 1.5 sq. degree near infrared survey called the Palomar Observatory Wide-Field IR Survey (POWIR), which was the largest NIR survey when completed.
I am also leading several efforts to carry out detailed analyses of the structures of high redshift galaxies as imaged with the Hubble Space Telescope, particularly with the GOODS and CANDELS programs of which I am a co-I. My other interest is in low mass galaxies and currently I am exploring the population in a Local Group analog, NGC 1375.