A photometricity and extinction monitor at the Apache Point Observatory

An unsupervised software "robot" that automatically and robustly reduces an d analyzes CCD observations of photometric standard stars is described. The robot measures extinction coefficients and other photometric parameters in real time and, more carefully, on the next day. It also reduces and analyz es data from an all-sky 10 mum camera to detect clouds; photometric data ta ken during cloudy periods are automatically rejected. The robot reports its findings to observers and data analysts via the World Wide Web. It can be used to assess photometricity and to build data on site conditions. The rob ot's automated and uniform site monitoring represents a minimum standard fo r any observing site with queue scheduling, a public data archive, or likel y participation in any future National Virtual Observatory.