The next generation virgo cluster survey-infrared (NGVS-IR). I. A new near-ultraviolet, optical, and near-infrared globular cluster selection tool

Roberto P. Muñoz, Thomas H. Puzia, Ariane Lançon, Eric W. Peng, Patrick Côté, Laura Ferrarese, John P. Blakeslee, Simona Mei, Jean Charles Cuillandre, Patrick Hudelot, Stéphane Courteau, Pierre Alain Duc, Michael L. Balogh, Alessandro Boselli, Frédéric Bournaud, Raymond G. Carlberg, Scott C. Chapman, Patrick Durrell, Paul Eigenthaler, Eric EmsellemGiuseppe Gavazzi, Stephen Gwyn, Marc Huertas-Company, Olivier Ilbert, Andrés Jordán, Ronald Läsker, Rossella Licitra, Chengze Liu, Lauren Macarthur, Alan McConnachie, Henry Joy McCracken, Yannick Mellier, Chien Y. Peng, Anand Raichoor, Matthew A. Taylor, John L. Tonry, R. Brent Tully, Hongxin Zhang

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69 Scopus citations


The NGVS-IR project (Next Generation Virgo Cluster Survey-Infrared) is a contiguous, near-infrared imaging survey of the Virgo cluster of galaxies. It complements the optical wide-field survey of Virgo (NGVS). In its current state, NGVS-IR consists of Ks -band imaging of 4 deg2 centered on M87 and J- and Ks -band imaging of 16 deg2 covering the region between M49 and M87. We present observations of the central 4 deg2 centered on Virgo's core region. The data were acquired with WIRCam on the Canada-France-Hawaii Telescope, and the total integration time was 41 hr distributed over 34 contiguous tiles. A survey-specific strategy was designed to account for extended galaxies while still measuring accurate sky brightness within the survey area. The average 5σ limiting magnitude is Ks = 24.4 AB mag, and the 50% completeness limit is Ks = 23.75 AB mag for point-source detections, when using only images with better than 0.″7 seeing (median seeing 0.″54). Star clusters are marginally resolved in these image stacks, and Virgo galaxies with AB mag arcsec-2 are detected. Combining the Ks data with optical and ultraviolet data, we build the uiKs color-color diagram, which allows a very clean color-based selection of globular clusters in Virgo. This diagnostic plot will provide reliable globular cluster candidates for spectroscopic follow-up campaigns, needed to continue the exploration of Virgo's photometric and kinematic substructures, and will help the design of future searches for globular clusters in extragalactic systems. We show that the new uiKs diagram displays significantly clearer substructure in the distribution of stars, globular clusters, and galaxies than the gzKs diagram - the NGVS + NGVS-IR equivalent of the BzK diagram that is widely used in cosmological surveys. Equipped with this powerful new tool, future NGVS-IR investigations based on the uiKs diagram will address the mapping and analysis of extended structures and compact stellar systems in and around Virgo galaxies.

Original languageEnglish (US)
Article number4
JournalAstrophysical Journal, Supplement Series
Issue number1
StatePublished - Jan 2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • galaxies: clusters: individual (Virgo)
  • galaxies: distances and redshifts
  • galaxies: luminosity function, mass function
  • galaxies: photometry
  • galaxies: star clusters: general


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