# An Optical Source Catalog of the North Ecliptic Pole Region

## TL;DR

This paper presents a deep, multi-band optical catalog of the North Ecliptic Pole region, identifying galaxy clusters and groups through color-redshift relations and photometric analysis.

## Contribution

It provides a new, extensive optical source catalog with reliable star-galaxy separation and applies empirical color-redshift relations to detect galaxy clusters.

## Key findings

- Catalog contains ~56,000 sources brighter than r'=23 mag.
- Identified two galaxy clusters and one galaxy group.
- Developed a method for separating point and extended sources at faint magnitudes.

## Abstract

We present a five (u*,g',r',i',z') band optical photometry catalog of the sources in the North Ecliptic Pole (NEP) region based on deep observations made with MegaCam at CFHT. The source catalog covers about 2 square degree area centered at the NEP and reaches depths of about 26 mag for u*, g', r' bands, about 25 mag for i' band, and about 24 mag for z' band (4 sigma detection over an 1 arcsec aperture). The total number of cataloged sources brighter than r'= 23 mag is about 56,000 including both point sources and extended sources. From the investigation of photometric properties using the color-magnitude diagrams and color-color diagrams, we have found that the colors of extended sources are mostly (u*-r') < 3.0 and (g'-z') > 0.5. This can be used to separate the extended sources from the point sources reliably, even for the faint source domain where typical morphological classification schemes hardly work efficiently. We have derived an empirical color-redshift relation of the red sequence galaxies using the Sloan Digital Sky Survey data. By applying this relation to our photometry catalog and searching for any spatial overdensities, we have found two galaxy clusters and one nearby galaxy group.