Observational performance of the KMTNet
Chung‐Uk Lee, Seung‐Lee Kim, Sang-Mok Cha, Yongseok Lee, Dong-Jin Kim, Byeong-Gon Park · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2014
Korea Astronomy and Space Science Institute have been developing the Korea Microlensing Telescope Network aka KMTNet consists of three identical 1.6-m wide-field optical telescopes. Each telescope covers 2 deg by 2 deg FOV with an 18k by 18k mosaic CCD camera to discover Earth mass extrasolar planets using a microlensing method. A predefined 4 deg by 4 deg Bulge area will be monitored for 24-hours with the help of almost equally located three southern observatories: Cerro Tololo Inter-American Observatory in Chile, South African Astronomical Observatory in South Africa and Siding-Spring Observatory in Australia. One of the required photometric performances of the system to accomplish its scientific goal is to secure 1% of magnitude uncertainty in the range of 13 < I < 18 at the heavily crowded Galactic bulge area. To minimize the blending effect and to maximize the photometric accuracy in the photometric process, we use the difference image analysis method for a data reduction pipeline that requires precise alignment and constant point spread function profile in the observed images. In this paper we present the test observation results and verify the observational performance of the first telescope installed at CTIO. From the test observation we obtained a pointing accuracy of 8.5 arcsec RMS, an open loop tracking accuracy of 0.166 arcsec for two minutes without autoguiding, a delivered image quality of 0.86, 0.86, 0.93, 0.98 arcsec in I, R, V, B–bands, and a photometric error of 1% for the stars with 17.0 magnitude in I-band using a prescience CCD camera which has a quantum efficiency of 30%.