ORAC: A modern observing system for UKIRT

The steady improvement in telescope performance at UKIRT and the increase in data acquisition rates led to a strong desire for an integrated observing framework that would meet the needs of future instrumentation, as well as providing some support for existing instrumentation. Thus the Observatory Reduction and Acquisition Control (ORAC) project was created in 1997 with the goals of improving the scientific productivity of the telescope, reducing the overall ongoing support requirements, and eventually supporting the use of more flexibly scheduled observing. The project was also expected to achieve this within a tight resource allocation. In October 1999 the ORAC system was commissioned at the United Kingdom Infrared Telescope (UKIRT). ORAC took a systems level approach to its overall design in creating an advance Preparation system, an Observatory Control System and a pipelined on-line Data Reduction system. Much of the system was designed and implemented using Object Oriented techniques and current software technologies, and attempts were made to re-use software from other projects where possible and appropriate. The design implemented is highly modular allowing future upgrading if necessary. The opportunity was also taken to implement the use of software "instrument apertures" on UKIRT. We describe the ORAC system, some of the design methods and comment on some of the issues to be tackled when attempting to use other people's software and in managing a distributed project.