The HST Exposure Time Calculators: Estimating Accurate Observing Times for HST Observations

摘要

The Exposure Time Calculators is a web application that assists users of the Hubble Space Telescope to predict observing times and signal to noise of mostly any possible object that can be observed by the telescope. Accurate predictions are key to determine the time needed to achieve the scientific goals of the observers. It is also used by the contact scientist at STScI to verify the safety and health of some of the instruments that could be damaged by bright observations. The system is key for the proposing and planning of HST observations. As a result it must be able to accurately predict observing times or expected signal-to-noise ratios for proposed observations. We discuss the issues that complicate developing a general tool that shares as much commonality for computing exposure times for different instruments while handling all the special issues that individual instruments have. Particular attention will be given to the new features and capabilities that have been added to support the new HST instruments, COS and WFC3.