A wide field survey at the Northern Ecliptic Pole I: Number counts and angular correlation functions in K

Abstract

We present the results from a multi colour survey performed at the Northern Ecliptic Pole (NEP). The survey is designed to identify the counterparts of faint sources from the ROSAT All Sky Survey and the IRAS survey and to study their optical/near-infrared properties. We observed the central square degree around the NEP in the optical bands B_J and R and in the near-infrared band K. A shallower survey was carried out in the optical I band. Here we present the results of the K-band survey. We discuss the source counts in the magnitude range 7mag < K < 17.5mag and the angular correlation function of galaxies with K < 17.0mag. The galaxy counts at the NEP display a subeuklidean slope in dlog(N)/dm. Our shallower slope does not require the large effects of galaxy evolution or density evolution suggested to explain the steeper slopes found in earlier surveys. The angular correlation function of galaxies follows a power law w(θ) = Aθ^-δwith A=5.7+-0.8 x 10^-3 and δ=0.98+-0.15. This is in accordance with the expected values for stable clustering.