The Korea Microlensing Telescope Network (KMTNet) is a network of three new 1.6-m, wide-field telescopes spread over three different sites in Chile, South Africa and Australia. Each telescope is equipped with a four square degree wide-field CCD camera, making the KMTNet an ideal facility for discovering and monitoring early supernovae and other rapidly evolving optical transients by providing 24-hour continuous sky coverage. We describe our inaugurating program of observing supernovae and optical transients using about 20% of the KMTNet time in 2015−2019. Our early results include detection of infant supernovae, novae and peculiar transients as well as numerous variable stars and low surface brightness objects such as dwarf galaxies.
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%.
We present the design, assembly, alignment, and verification process of the wide field corrector for the Korea Microlensing Telescope Network (KMTNet) 1.6 meter optical telescope. The optical configuration of the KMTNet telescope is prime focus, having a wide field corrector and the CCD camera on the topside of Optical Tube Assembly (OTA). The corrector is made of four lenses designed to have all spherical surfaces, being the largest one of 552 mm physical diameter. Combining with a purely parabolic primary mirror, this optical design makes easier to fabricate, to align, and to test the wide field optics. The centering process of the optics in the lens cell was performed on a precision rotary table using an indicator. After the centering, we mounted three large and heavy lenses on each cell by injecting the continuous Room Temperature Vulcanizing (RTV) silicon rubber bonding via a syringe.