Published online by Cambridge University Press: 01 May 2008
HATNet is a network of six identical, fully automated wide field telescopes, four of which are located in Arizona, and two at Hawaii. The purpose of the network is to search for transiting extrasolar planets around relatively bright stars (8 < I < 12). The longitudinal coverage of 3.5 hours greatly enhances transit detection efficiency. HATNet has been operational since 2004, and has taken more than 1/2 million science frames at 5-min integrations, covering about 7% of the sky. Photometric precision reaches 3mmag rms at 5.5 min cadence at I ≈ 8, and is 1% at I ≈ 11.3. Hundreds of transit candidates have been detected in the data, and have been subject to vigorous follow-up by various 1m-class facilities, both spectroscopy and follow-up photometry. A fraction of the candidates that have survived these steps as not being false alarms have been observed by high resolution and precision spectrographs (primarily Keck/HIRES), to confirm their planetary nature and characterize their properties. So far nine transiting planets have been reported, making HATNet a very successful survey.