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.
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.
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%.
The KMTNet telescope Project, sponsored by The Korea Astronomy and Space Science Institute (KASI), is fabricating
three wide-field equatorial mount telescopes of 1.6 meter aperture to conduct continuous observations of the Galactic
bulge region to search for extra-solar planets. Southern latitude sites secured for these telescopes are SAAO (South
Africa), CTIO (Chile), and SSO (Australia). A prime-focus configuration, along with a four-lens corrector achieves the
2.8 degree diagonal FOV. The basic mechanical design utilizes a scaled-up version of the successful 2MASS Telescopes
built by the authors in the late 1990's. Scaling up of components has presented challenges requiring several iterations of
the detailed mechanical analysis as well as the optical analysis due to interaction with mounting assemblies for the
optical components. A flexure-style focus mechanism, driven by three precision actuators, moves the entire headring
assembly and provides real-time focus capability, and active primary mirror cooling is implemented for the Zerodur
primary. KMTNet engineering specifications are met with the current design, which uses Comsoft's Legacy PCTCS for
control. A complete operational telescope and enclosure are scheduled for installation in Tucson, AZ prior to shipping
the first hardware to CTIO in order to verify tracking, optical characteristics at various attitudes, and overall observatory
functionality. The cameras, being fabricated by The Ohio State University Department of Astronomy, Imaging Sciences
Laboratory (ISL), are proceeding in parallel with the telescope fabrication, and that interface is now fixed. Specifics of
the mechanical and optical design are presented, along with the current fabrication progress and testing protocols.
We are developing three 1.6m optical telescopes and 18k by 18k mosaic CCD cameras. These telescopes will be
installed and operated at three southern astronomical sites in Chile, South Africa, and Australia for the Korea
Microlensing Telescope Network (KMTNet) project. The main scientific goal of the project is to discover earth-like
extrasolar planets using the gravitational microlensing technique. To achieve the goal, each telescope at three sites will
continuously monitor the specific region of Galactic bulge with 2.5 minute cadence for five years. Assuming 12 hour
observation in maximum for a night, the amount of 200GB file space is required for one-night observations at each
observatory. If we consider the whole project period and the data processing procedure, a few PB class data storage,
high-speed network, and high performance computers are essential. In this paper, we introduce the KMTNet data
management plan that handles gigantic data; observation data collecting, image calibration, data reduction pipeline,
database archiving, and backup.
We present the design for the 340 Mpixel KMTNet CCD camera comprising four newly developed e2v CCD290-99
imaging sensors mounted to a common focal plane assembly. The high performance CCDs have 9k x 9k format, 10
micron pixels, and multiple outputs for rapid readout time. The camera Dewar is cooled using closed cycle coolers and
vacuum is maintained with a cryosorption pump. The CCD controller electronics, the electronics cooling system, and the
camera control software are also described.
TBR Construction and Engineering (TBR) has under development for the Korea Astronomy and Space Science Institute (KASI), a project to provide three 1.6 meter optical telescopes observatories in three southern countries: Chile, South Africa, and Australia. The contracting team has chosen to develop a full scale prototype of the observatory. This will become a functional assembly and testing facility for all three project telescopes in Tucson, Arizona. This prototyping concept is meant to allow the optics team to make changes to the observatory as needed for the scientific mission while minimizing the expense of making changes in remote countries.
We present the science cases with the Korea Microlensing Telescope Network (KMTNet) which consists of three widefield
1.6 m telescopes distributed in Chile, South Africa, and Australia, respectively, providing unique continuous sky
coverage with the three telescopes. The primary scientific goal of the KMTNet project is to explore the structure and
diversity of planetary systems and variable objects. Since the system is mainly optimized to conduct gravitational
microlensing surveys, it will enable detections of very low-mass exoplanets, potentially down to the mass of Mars that
are inaccessible by other ground-based techniques. In addition to the primary science, it is possible to conduct a variety
of other observational programs with the KMTNet system, including photometric studies of nearby galaxies and galaxy
clusters, discovery of supernovae and their follow-up observations, and observations of near-Earth objects. We expect
synergies between the KMTNet project with other similar or complementary projects in the southern sky, such as
The Korea Astronomy and Space Science Institute (KASI) are under development three 1.6m optical telescopes for the
Korea Micro-lensing Telescope Network (KMTNet) project. These will be installed at three southern observatories in
Chile, South Africa, and Australia by middle 2014 to monitor dense star fields like the Galactic bulge and Large
Magellanic Cloud. The primary scientific goal of the project is to discover numerous extra-solar planets using the
gravitational micro-lensing technique. We have completed the final design of the telescope. The most critical design
issue was wide-field optics. The project science requires the Delivered Image Quality (DIQ) of less than 1.0 arcsec
FWHM within 1.2 degree radius FOV, under atmospheric seeing of 0.75 arcsec. We chose the prime-focus configuration
and realized the DIQ requirement by using a purely parabolic primary mirror and four corrector lenses with all spherical
surfaces. We present design results of the wide-field optics, the primary mirror coating and support, and the focus system
with three linear actuators on the head ring.
Korea Astronomy and Space Science Institute (KASI) has officially started a project to construct an astronomical widefield
survey system, namely KMTNet (Korea Micro-lensing Telescope Network), from January 2009. Its primary
scientific goal is to discover numerous extra-solar planets, especially earth-mass planets, using the gravitational microlensing
technique. This goal requires continuous photometric observations with high cadence of about 10 minutes for
tens of millions of stars in dense fields toward the Galactic bulge. KMTNet will comprise three identical systems at
southern observatories with different time zones. Each observing system consists of a 1.6 m wide-field optical telescope
and a 20k by 20k mosaic CCD camera, which covers a 2 by 2 degrees square field of view. In this proceeding, we
present technical specifications, designs and fabrication schedule of the KMTNet system.