ar X iv : a st ro - p h / 05 07 61 2 v 1 26 J ul 2 00 5 SHADES survey design 1 The SCUBA HAlf Degree Extragalactic

The SCUBA HAlf Degree Extragalactic Survey (SHADES) is a major new blank-field extragalactic sub-mm survey currently underway at the James Clerk Maxwell telescope. Ultimately, SHADES aims to cover half a square degree at 450 and 850μm to a 4-σ depth of ≃ 8mJy at 850μm. Two fields are being observed, the Subaru/XMM– Newton Deep Field (SXDF) (0218−05) and the Lockman Hole East (1052+57). The survey has three main aims: i) to investigate the population of high-redshift submm galaxies and the cosmic history of massive dust enshrouded star-formation activity, ii) to investigate the clustering properties of sub-mm–selected galaxies in order to determine whether these objects could be progenitors of present-day massive ellipticals, and iii) to investigate the fraction of sub-mm-selected sources that harbour active galactic nuclei. To achieve these aims requires that the sub-mm data be combined with co-spatial information spanning the radio–to–X-ray frequency range. Accordingly SHADES has been designed to benefit from ultra-deep radio imaging obtained with the VLA, deep mid-infrared observations from the Spitzer Space Telescope, sub-mm mapping by the Balloon-borne Large Area Sub-millimetre Telescope (BLAST), deep near-infrared imaging with the UK Infrared Telescope, deep optical imaging with the Subaru telescope, and deep X-ray observations with the XMM–Newton observatory. It is expected that the resulting extensive multi-wavelength dataset will provide complete photometric redshift information accurate to δz < ∼ 0.5, as well as detailed spectral energy distributions for the vast majority of the sub-mm-selected sources. In this paper, the first of a series on SHADES, we present an overview of the motivation for the survey, describe the SHADES survey strategy, provide a detailed description of the primary data analysis pipeline, and demonstrate the superiority of our adopted matched-filter source extraction technique over, for example, Emerson-II style methods. We also report on the progress of the survey. As of February 2004, 720 arcmin had been mapped with SCUBA (about 40% of the anticipated final total area) to a median 1 σ depth of 2.2mJy per beam at 850μm (25mJy per beam at 450μm), and the source extraction routines give a source density of 650±50 sources deg > 3 σ at 850μm. Although uncorrected for Eddington bias, this source density is more than sufficient for providing enough sources to answer the science goals of SHADES once half a square degree is observed. A refined re-analysis of the original 8-mJy survey Lockman hole data was carried out in order to evaluate the new data reduction pipeline. Of the 17 most secure sources in the original sample, 12 have been re-confirmed, including ten of the eleven for which radio identifications were previously secured.