Optical-near-infrared catalog for the AKARI north ecliptic pole Deep field

Aims. We present an 8-band (u*, g', r', i', z', Y, J, K_s) optical to near-infrared deep photometric catalog based on the observations made with MegaCam and WIRCam at the CFHT, and compute photometric redshifts, z _p in the north ecliptic pole (NEP) region. AKARI infrared satellite carried out a deep survey in the NEP region at near-to mid-infrared wavelengths. Our optical to near-infrared catalog allows us to identify the counterparts and z_p for the AKARI sources. Methods. We obtained seven-band (g', r', i', z', Y, J, K_s) imaging data, and we crossmatched them with existing u*-band data (limiting magnitude = 24.6 mag [5σ; AB]) to design the band-merged catalog. We included all z'-band sources with counterparts in at least one of the other bands in the catalog. We used a template-fitting methods to compute z_p for all the cataloged sources. Results. The estimated 4σ detection limits within a 1 arcsec aperture radius are 26.7, 25.9, 25.1, and 24.1 mag [AB] for the optical g', r', i', and z'-bands and 23.4, 23.0, and 22.7 mag for the near-infrared Y, J, and K _s-bands, respectively. There are a total of 85-797 sources in the band-merged catalog. An astrometric accuracy of this catalog determined by examining coordinate offsets with regard to 2MASS is 0.013 arcsec with a root mean square offset of 0.32 arcsec. We distinguish 5441 secure stars from extended sources using the u*-J versus g'-K_s colours, combined with the SExtractor stellarity index of the images. Comparing with galaxy spectroscopic redshifts, we find a photometric redshift dispersion, σ_{Δz/(1 + z)}, of 0.032 and catastrophic failure rate, Δz/(1 + z) 0.150.15$;Δz1+z 0.15, of 5.8% at z< 1, while a dispersion of 0.117 and a catastrophic failure rate of 16.6% at z> 1. We extend the estimate of the z_p uncertainty over the full magnitude/redshift space with a redshift probability distribution function and find that our redshifts are highly accurate with z' < 22 at z_p< 2.5 and for fainter sources with z' < 24 at z_p< 1. From the investigation of photometric properties of AKARI infrared sources (23-354 sources) using the g'z'K_s diagram, < 5% of AKARI sources with optical counterparts are classified as high-z (1.4 <z< 2.5) star-forming galaxies. Among the high-z star-forming galaxies, AKARI mid-infrared detected sources seem to be affected by stronger dust extinction compared with sources with non-detections in the AKARI mid-infrared bands.