<title>ORAC: a modern observing system for UKIRT</title>

Abstract

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.

Optically Faint Counterparts to theInfrared Space ObservatoryFIRBACK 170 Micron Population: Discovery of Cold, Luminous Galaxies at High Redshift

“…Each source was imaged for a total of 1800 s, with individual exposures of 60 s each, reaching a limiting magnitude in a 2 ′′ diameter aperture of K = 20.4 (5σ) in 0.4 ′′ seeing. Data were reduced using the UKIRT software pipeline oracdr (Bridger et al 2000).…”

Submillimetre and near-infrared observations of galaxies selected at 170 m

“…The fast tip/tilt, adaptively corrected imaging resulted in seeing better than median conditions, at ≃0.4 arcsec FWHM. Data were reduced using the Starlink, UKIRT/UFTI image processing tools under the oracdr environment (Bridger et al 2000). We wrote custom oracdr scripts to optimize point source sensitivity in our essentially blank field observations, creating flat fields from each 9-point dither, and high signal-to-noise thermal background images from 60 minutes of data centered around the observing period of each target.…”

Learning from 25 years of the extensible N-Dimensional Data Format

“…Appendix A.2) for CGS3 and CGS4 (Wright et al, 1993). NDF was adopted at UKIRT in 1995 although a unified UKIRT NDFbased data model for all instruments, involving HDS containers of NDF structures to handle multiple exposures, was not adopted until the release of the ORAC system (Bridger et al, 2000). The James Clerk Maxwell Telescope (JCMT) initially used a proposed submillimeter standard format known as the Global Section Datafile (GSD; Jenness et al, 1999, formerly General Single Dish Data).…”