2012A&A...548A..29K

We present a photometric catalog of infrared (IR) sources based on the North Ecliptic Pole Wide field (NEP-Wide) survey of AKARI, which is an infrared space telescope launched by Japan. The NEP-Wide survey covered 5.4deg² area, a nearly circular shape centered on the NEP, using nine photometric filter-bands from 2-25µm of the Infrared Camera (IRC). Extensive efforts were made to reduce possible false objects due to cosmic ray hits, multiplexer bleeding phenomena around bright sources, and other artifacts. The number of detected sources varied depending on the filter band: with about 109000 sources being cataloged in the near-infrared (NIR) bands at 2-5µm, about 20000 sources in the shorter parts of the mid-infrard (MIR) bands between 7-11µm, and about 16000 sources in the longer parts of the MIR band, with ∼4000 sources at 24µm. The estimated 5σ detection limits are approximately 21mag (mag) in the 2-5µm bands, 19.5-19mag in the 7-11µm, and 18.8-18.5mag in the 15-24µm bands in the AB magnitude scale. The completenesses for those bands were evaluated as a function of magnitude: the 50% completeness limits are about 19.8mag at 3µm, 18.6 mag at 9µm, and 18mag at 18µm band, respectively. To construct a reliable source catalog, all of the detected sources were examined by matching them with those in other wavelength data, including optical and ground-based NIR bands. The final band-merged catalog contains about 114800 sources detected in the IRC filter bands. The properties of the sources are presented in terms of the distributions in various color-color diagrams.