exposure time

The term exposure time is used for telescopes for the time over which data is collected. The term can be used for a single image (or spectrum) or can be used for the sum of such exposure times associated with an image or astronomical survey. It is a photography term referring to the amount of time the photographic film or plate is exposed for capturing the image, which is relevant to astronomy, and is now commonly used for CCDs and analogous sensors. Selecting exposure times is relevant in amateur astronomy to astrophotography, and is virtually always of interest in observations in modern research astronomy. In radio astronomy the analogous term integration time is generally used. The photography term shudder speed means the exposure time of a single exposure.