The North Ecliptic Pole Wide survey of AKARI: a near- and mid-infrared source catalog^⋆

¹ Astronomy Program, Department of Physics and Astronomy, FPRDSeoul National University, Kwanak-Gu, 151-742 Seoul, Republic of Korea
e-mail: hmlee@snu.ac.kr
² Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, 229-8510 Kanagawa, Japan
³ Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602 Aichi, Japan
⁴ Korea Astronomy and Space Science Institute, 305-348 Deajeon, Republic of Korea
⁵ Yonsei University Observatory, Yonsei University, 120-749 Seoul, Republic of Korea
⁶ RALSpace, The Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK
⁷ Astrophysics Group, Department of Physics, The Open University, Milton Keynes, MK7 6AA, UK
⁸ Academia Sinica, Institute of Astronomy and Astrophysics, Taiwan
⁹ Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI, 96822, USA
¹⁰ Department of Particle and Astrophysical Science, Nagoya University, Furo-cho, Chikusa-ku, 464-8602 Nagoya, Japan
¹¹ The Astronomical Observatory of the Jagiellonian University, ul. Orla 171, 30-244 Kraków, Poland
¹² Polish Academy of Sciences, al. Lotników, 32/46, 02-668 Warsaw, Poland
¹³ The Andrzej Sołtan National Centre for Nuclear Research, ul. Hoża 69, 00-681 Warsaw, Poland

Received: 24 February 2012
Accepted: 23 July 2012

Abstract

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 5.4 deg² area, a nearly circular shape centered on the NEP, using nine photometric filter-bands from 2−25 μm 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 109 000 sources being cataloged in the near-infrared (NIR) bands at 2−5 μm, about 20 000 sources in the shorter parts of the mid-infrard (MIR) bands between 7−11 μm, and about 16 000 sources in the longer parts of the MIR band, with  ~4000 sources at 24 μm. The estimated 5σ detection limits are approximately 21 mag (mag) in the 2−5 μm bands, 19.5−19 mag in the 7−11 μm, and 18.8−18.5 mag in the 15−24 μm bands in the AB magnitude scale. The completenesses for those bands were evaluated as a function of magnitude: the 50% completeness limits are about 19.8 mag at 3 μm, 18.6 mag at 9 μm, and 18 mag at 18 μm 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 114 800 sources detected in the IRC filter bands. The properties of the sources are presented in terms of the distributions in various color–color diagrams.