The SCUBA Legacy Catalogue

1. The SCUBA Legacy Catalogue • J. Di Francesco1,2, D. Johnstone1,2, H. Kirk2,1, T. MacKenzie3,1 & E. Ledwosinska4,1 • National Research Council of Canada, Herzberg Institute of Astrophysics • (2) University of Victoria, Department of Physics and Astronomy • (3) University of Prince Edward Island, Department of Physics • (4) McGill University, Physics Department Abstract: The Submillimetre Common User Array (SCUBA) was one of the flagship instruments of the James Clerk Maxwell Telescope (JCMT). From 1997 to 2005, SCUBA was used regularly to observe simultaneously 850 mm and 450 mm continuum emission from a variety of astronomical phenomena. To maximize the scientific return and relevance of SCUBA, we have re-reduced uniformly all 850 mm and 450 mm jiggle- and scan-map data (of objects outside the Solar System) within the JCMT public archive. Specifically, data from the same positions but over several epochs were combined into single maps to maximize sensitivities. In this poster, we present several examples of images from the SCUBA Legacy Image Dataset and describe the SCUBA Legacy Catalogue derived from the Dataset. The Dataset and Catalogue will soon be available for public use at http://cadc.hia.nrc.ca . Images: 28,534 individual data files were sorted into 1.2o x 1.2o fields across the sky. Each file had applied to it respectively the most up-to-date opacity and flux calibration factors. (Bad data were systematically removed.) The Core Image Dataset, containing 1425 fields at 850 mm and 1359 fields at 450 mm, was made using only SCUBA data with excellent opacity correction data. The Extended Image Dataset, containing 1549 fields at 850 mm only, was made using all data of at least reasonable quality. In both cases, fields were imaged using the ``matrix inver-sion” technique of Johnstone et al. (2000; ApJS, 131, 505), which can be used generally for maps where noise varies across the field. The 850 mm and 450 mm fields were made respectively with 6” and 3” pixels for respect-ive resolutions of ~19.5” FWHM and ~11.0” FWHM. The SCUBA Legacy Image Dataset is comprised of both of these Datasets.Above, we show examples of 850 mm maps from the Extended Image Dataset. Catalogues: Each 850 mm field was analyzed with the 2-D CLUMPFIND identification algorithm (Williams, de Geus & Blitz 1994; ApJ, 428, 693) to produce a list of objects of minimum local median S/N = 3 and size of 8 pixels, the beam FWHM (see above for object examples). The SCUBA Legacy Catalogue is comprised of the re- sulting Core Map Object Catalogue (CMOC; 6350 objects) and Extended Map Object Catalogue (EMOC; 7516 objects). Objects are named as JCMT HHMMSSS+/-DDMMSS using their J2000 positions of peak flux at 850 mm. The CMOC & EMOC each list 850m total and peak fluxes, object size, and local median S/N. Due to more var- iable opacities at 450 mm, objects were not identified independently at 450 mm; instead the CMOC lists total and peak fluxes at 450 mm for each object from positions identified with that object by CLUMPFIND at 850 mm.