Increasing observing efficiency by modeling telescope focus positions - art. no. 70183W

With the advent Of Queue observing at the Canada-France-Hawaii Telescope (CHAT). much emphasis has been placed oil minimizing the overheads in the observing process. Ensuring telescope focus is a necessary overhead, but taking the focus sequences required to keep focus during the night adds significant time. In order to nearly eliminate this overhead Without sacrificing good telescope focus, the necessary focus position for each instrument has been modeled as a function of telescope temperature and position oil the sky. The correct focus position is calculated instead of measured, SO Focus updates are practically instantaneous. The model coefficients are updated with new data regularly. Automatic focus using calculated focus positions has been implemented for MegaCam, WIRCam and ESPaDOnS.