A deep survey of the AKARI north ecliptic pole field . I. WSRT 20 cm radio survey description, observations and data reduction
Im, M.; Lee, H. M.; White, G. J.; Serjeant, S.; Braun, R.; Pearson, C.; Takagi, T.; Goto, T.; Matsuhara, H.; Oyabu, S.; Wada, T.; Lee, M. G.; Nakagawa, T.; Hwang, N.; Hanami, H.; Shipman, R.; Oliver, S.; Barthel, P.; Pak, S.; Chun, M. -Y.
United Kingdom, Canada, Australia, Japan, Netherlands, South Korea, United States
Abstract
Aims: The Westerbork Radio Synthesis Telescope, WSRT, has been used to make a deep radio survey of an ~1.7 degree2 field coinciding with the AKARI north ecliptic pole deep field. The observations, data reduction and source count analysis are presented, along with a description of the overall scientific objectives.
Methods: The survey consisted of 10 pointings, mosaiced with enough overlap to maintain a similar sensitivity across the central region that reached as low as 21 μJy beam-1 at 1.4 GHz.
Results: A catalogue containing 462 sources detected with a resolution of 17.0'' × 15.5'' is presented. The differential source counts calculated from the WSRT data have been compared with those from the shallow VLA-NEP survey of Kollgaard et al. 1994, and show a pronounced excess for sources fainter than ~1 mJy, consistent with the presence of a population of star forming galaxies at sub-mJy flux levels.
Conclusions: The AKARI north ecliptic pole deep field is the focus of a major observing campaign conducted across the entire spectral region. The combination of these data sets, along with the deep nature of the radio observations will allow unique studies of a large range of topics including the redshift evolution of the luminosity function of radio sources, the clustering environment of radio galaxies, the nature of obscured radio-loud active galactic nuclei, and the radio/far-infrared correlation for distant galaxies. This catalogue provides the basic data set for a future series of paper dealing with source identifications, morphologies, and the associated properties of the identified radio sources.