The VST photometric hα survey of the Southern Galactic Plane and Bulge (VPHAS+)

J.E. Drew, Eduardo A. González-Solares, Robert Greimel, M.J. Irwin, A. Küpcü Yoldaş, J.R. Lewis, Geert Barentsen, Jochen Eislöffel, Hywel J. Farnhill, Bill Martin, Nicholas A. Walton, M. Mohr-Smith, Roberto Raddi, Stuart E. Sale, Nicholas J. Wright, Paul J. Groot, Michael J. Barlow, R.L.M. Corradi, Jeremy J. Drake, Juan FabregatDavid J. Frew, Boris T. Gänsicke, Christian Knigge, Antonio Mampaso, R.A.H. Morris, Tim J. Naylor, Quentin A. Parker, Steven Phillipps, Christine Ruhland, Danny T H Steeghs, Y.C. Unruh, Jorick S. Vink, Roger Wesson, Albert Zijlstra

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The VST Photometric Hα Survey of the Southern Galactic Plane and Bulge (VPHAS+) is surveying the southern Milky Way in u, g, r, i and Hα at ~1 arcsec angular resolution. Its footprint spans the Galactic latitude range -5o <b <+5° at all longitudes south of the celestial equator. Extensions around the Galactic Centre to Galactic latitudes ±10° bring in much of the Galactic bulge. This European Southern Observatory public survey, begun on 2011 December 28, reaches down to ~20th magnitude (10σ) and will provide single-epoch digital optical photometry for ~300 million stars. The observing strategy and data pipelining are described, and an appraisal of the segmented narrow-band Hα filter in use is presented. Using model atmospheres and library spectra, we compute main-sequence (u - g), (g - r), (r - i) and (r - Hα) stellar colours in the Vega system. We report on a preliminary validation of the photometry using test data obtained from two pointings overlapping the Sloan Digital Sky Survey. An example of the (u - g, g - r) and (r - Hα, r - i) diagrams for a full VPHAS+ survey field is given. Attention is drawn to the opportunities for studies of compact nebulae and nebular morphologies that arise from the image quality being achieved. The value of the u band as the means to identify planetary-nebula central stars is demonstrated by the discovery of the central star of NGC 2899 in survey data. Thanks to its excellent imaging performance, the VLT Survey Telescope (VST)/OmegaCam combination used by this survey is a perfect vehicle for automated searches for reddened early-type stars, and will allow the discovery and analysis of compact binaries, white dwarfs and transient sources.
Original languageEnglish
Pages (from-to)2036-2058
Number of pages23
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Early online date2 Apr 2014
Publication statusPublished - 21 May 2014


  • Galaxy: bulge
  • Galaxy: disc
  • H II regions
  • Planetary nebulae: general
  • Stars: general
  • Surveys


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