Unobscured QSOs in ecliptic poles from KMTNet & PS1

For this purpose, we obtain deep broadband optical images of the SEP field covering an area of ~14.5x14.5deg^2^ with the Korea Microlensing Telescope Network (KMTNet). The 5{sigma} detection limits for point sources in the BVRI bands are estimated to be ~22.59, 22.60, 22.98, and 21.85mag, respectively.

Utilizing data from the Wide-field Infrared Survey Explorer, unobscured QSO candidates are selected among the optically pointlike sources using mid-infrared (MIR) and optical-MIR colors. To refine our selection further and eliminate any contamination not adequately removed by the color-based selection, we perform spectral energy distribution fitting with archival photometric data ranging from optical to MIR. As a result, we identify a total of 2383 unobscured QSO candidates in the SEP field.