The Next Generation Virgo Cluster Survey - Infrared (NGVS-IR): I. A new Near-
UV/Optical/Near-IR Globular Cluster selection tool

The NGVS-IR project (Next Generation Virgo 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). The current state of NGVS-IR 
consists of Ks-band imaging of 4 deg^2 centered on M87, and J and Ks-band 
imaging of 16 deg^2 covering the region between M49 and M87. In this paper, we 
present the observations of the central 4 deg^2 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 hours distributed in 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 5\sigma 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 
\mu_Ks=24.4 AB mag arcsec^-2 are detected. Combining the Ks data with optical 
and ultraviolet data, we build the uiK 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 sub-structures, and will help the design of future searches for 
globular clusters in extragalactic systems. Equipped with this powerful new 
tool, future NGVS-IR investigations based on the uiK diagram will address the 
mapping and analysis of extended structures and compact stellar systems in and 
around Virgo galaxies.