A Pipeline For Automatically Processing And Analysing Archival Images From Multiple Instruments

To take advantage of the recent upsurge in astrophysical research applications of grid technologies coupled with the increase in temporal and spatial coverage afforded to us by dedicated all-sky surveys and on-line data archives, we have developed an automated image reduction and analysis pipeline for a number of different astronomical instruments. The primary science goal of the project is in the study of long-term optical variability of brown dwarfs; although it can e tailored to suit many varied astrophysical phenomena. The pipeline complements Querator,(1) the custom search-engine which accesses the astronomical image archives based at the ST-ECF/ESO centre in Garching; Germany. To increase our dataset we complement the reduction and analysis of WFI (Wide 0 Field Imager, mounted on the 2.2-m MPG/ESO telescope at La Silla) archival images with the analysis of pre-reduced co-spatial HST/WFPC2 images and near infrared images from the DENIS archive. Our pipeline includes CCD-image reduction, registration, astrometry, photometry, and image matching stages. We present sample results of all stages of the pipeline and describe how we overcome such problems as missing or incorrect image meta data, interference fringing, poor image calibration files etc. The pipeline was written using tasks contained in the IRAF environment, linked together with Unix Shell Scripts and Perl, and the image reduction and analysis is performed using a 40-processor Origin SGI 3800 based at NUI, Galway.