Abstract:
The Neighbourhood Watch is a survey to complete a census of all baryonic structures out to at least the virial radius in a sample of galaxy groups within 18 Mpc in the optical filters u’g’r’i’ and H-alpha with CTIO/DECam and in the NIR J,K filters with ESO/VIRCAM. Serving as a critical pathfinder for LSST, our survey provides data in u’ that exceeds LSST’s planned 10-year depth a decade in advance, while complementing future LSST imaging in g’ and i’ bands. The observations reach unprecedented point source depths of 2.5 magnitudes beyond the peak of the globular cluster luminosity function (GCLF), detecting >99% of all compact objects and revealing low-surface brightness structures down to ∼28mags/arcsec². This dataset establishes a local universe benchmark for LSST by enabling the first complete GCLF measurements to the virial radius, detection of spatial over-densities in GC populations, discovery of 10-100 new low-surface brightness dwarf galaxies per target group, and detailed mapping of group histories. Our custom reduction pipeline, developed to overcome DECam community pipeline limitations in sky determination around large galaxies, employs advanced processing techniques similar to LSST data processing strategies. Our poster presents the survey overview, pipeline innovations, and results demonstrating our approach’s value as both a technical and scientific precursor to LSST.
