The Korea Microlensing Telescope Network (KMTNet) is a wide-field photometric system installed by the Korea Astronomy and Space Science Institute (KASI). Here, we present the overall technical specifications of the KMTNet observation system, test observation results, data transfer and image processing procedure, and finally, the KMTNet science programs. The system consists of three 1.6 m wide-field optical telescopes equipped with mosaic CCD cameras of 18k by 18k pixels. Each telescope provides a 2.0 by 2.0 square degree field of view. We have finished installing all three telescopes and cameras sequentially at the Cerro-Tololo Inter-American Observatory (CTIO) in Chile, the South African Astronomical Observatory (SAAO) in South Africa, and the Siding Spring Observatory (SSO) in Australia. This network of telescopes, which is spread over three different continents at a similar latitude of about −30 degrees, enables 24-hour continuous monitoring of targets observable in the Southern Hemisphere. The test observations showed good image quality that meets the seeing requirement of less than 1.0 arcsec in I-band. All of the observation data are transferred to the KMTNet data center at KASI via the international network communication and are processed with the KMTNet data pipeline. The primary scientific goal of the KMTNet is to discover numerous extrasolar planets toward the Galactic bulge by using the gravitational microlensing technique, especially earth-mass planets in the habitable zone. During the non-bulge season, the system is used for wide-field photometric survey science on supernovae, asteroids, and external galaxies.

The SPEAR (or 'FIMS') instrumentation has been used to conduct the first large-scale spectral mapping of diffuse cosmic far ultraviolet (FUV, 900-1750 AA) emission, including important diagnostics of interstellar hot (10^4 K - 10^6 K) and photoionized plasmas, H_2, and dust scattered starlight. The instrumentation's performance has allowed for the unprecedented detection of astrophysical diffuse far UV emission lines. A spectral resolution of 550 and an imaging resolution of 5' is achieved on-orbit in the Short (900 - 1175 AA) and Long (1335 - 1750 AA) bandpass channels within their respective 7.4 deg x 4.3' and 4.0 deg x 4.6' fields of view. We describe the SPEAR imaging spectrographs, their performance, and the nature and handling of their data

We present a library of high-resolution (R ≡ λ/∆λ ∼ 45,000) and high signal-to-noise ratio (S/N ≥ 200) near-infrared spectra for stars of a wide range of spectral types and luminosity classes. The spectra were obtained with the Immersion GRating INfrared Spectrograph (IGRINS) covering the full range of the H (1.496-1.780 µm) and K (2.080-2.460 µm) atmospheric windows. The targets were primarily selected for being MK standard stars covering a wide range of effective temperatures and surface gravities with metallicities close to the Solar value. Currently, the library includes flux-calibrated and telluric-absorption-corrected spectra of 84 stars, with prospects for expansion to provide denser coverage of the parametric space. Throughout the H and K atmospheric windows, we 2 Park et al.identified spectral lines that are sensitive to T eff or log g and defined corresponding spectral indices.We also provide their equivalent widths. For those indices, we derive empirical relations between the measured equivalent widths and the stellar atmospheric parameters. Therefore, the derived empirical equations can be used to calculate T eff and log g of a star without requiring stellar atmospheric models.

The "Spectroscopy of Plasma Evolution from Astrophysical Radiation" (SPEAR, also known as the "FarUltraviolet Imaging Spectrograph") instruments, flown aboard the STSAT-1 satellite mission, have provided the first large-area spectral mapping of the cosmic far-ultraviolet (FUV; 900-1750 ) background. We describe the A mission and its science motivation, the mission data and their processing, and the effects of mission performance on the science data. We present the first map of the cosmic FUV background (1360-1710 ) over most of the A sky as an example of the mission results. These SPEAR data reveal diffuse radiation from warm and hot (10 4 -10 6 K) plasma, molecular hydrogen fluorescence, and dust-scattered starlight. They allow for an unprecedented characterization of the spectral emission from a variety of environments, including the general interstellar medium (ISM), molecular clouds, supernova remnants, and superbubbles.

The Immersion Grating Infrared Spectrometer (IGRINS) is a compact high-resolution near-infrared cross-dispersed spectrograph whose primary disperser is a silicon immersion grating. IGRINS covers the entire portion of the wavelength range between 1.45 and 2.45μm that is accessible from the ground and does so in a single exposure with a resolving power of 40,000. Individual volume phase holographic (VPH) gratings serve as cross-dispersing elements for separate spectrograph arms covering the H and K bands. On the 2.7m Harlan J. Smith telescope at the McDonald Observatory, the slit size is 1ʺ x 15ʺ and the plate scale is 0.27ʺ pixel -1 . The spectrograph employs two 2048 x 2048 pixel Teledyne Scientific & Imaging HAWAII-2RG detectors with SIDECAR ASIC cryogenic controllers. The instrument includes four subsystems; a calibration unit, an input relay optics module, a slit-viewing camera, and nearly identical H and K spectrograph modules. The use of a silicon immersion grating and a compact white pupil design allows the spectrograph collimated beam size to be only 25mm, which permits a moderately sized (0.96m x 0.6m x 0.38m) rectangular cryostat to contain the entire spectrograph. The fabrication and assembly of the optical and mechanical components were completed in 2013. We describe the major design characteristics of the instrument including the system requirements and the technical strategy to meet them. We also present early performance test results obtained from the commissioning runs at the McDonald Observatory.

We present the first far-ultraviolet (FUV; 1370Y1670 8) image of the Ophiuchus molecular cloud region, observed with the SPEAR imaging spectrograph. The flux levels of the diffuse FUV continuum are in reasonable agreement with those of the Voyager observations in the shorter FUV wavelengths (912Y1216 8), provided that the diffuse FUV emission is dominated by the spectra from late O-and early B-type stars. The observed region of the present study was divided into five subregions according to their FUV intensities, and the spectrum was obtained for each subregion with prominent H 2 fluorescent emission lines. A synthetic model of the H 2 fluorescent emission indicates that the molecular cloud has more or less uniform physical parameters over the Ophiuchus region, with a hydrogen density n H of 500 cm À3 and a H 2 column density N(H 2 ) of 2 ; 10 20 cm À2 . It is notable that the observed diffuse FUV continuum is well reproduced by a single-scattering model with scattered starlight from the dust cloud located at $120Y130 pc, except at a couple of regions with high optical depth. The model also gives reasonable properties of the dust grains of the cloud with an albedo a of 0:36 AE 0:20 and a phase function asymmetry factor g of 0:52 AE 0:22. Subject headingg s: ISM: individual (Ophiuchus) -ISM: lines and bands -ultraviolet: ISM

From high resolution (R ; 45,000), high signal-to-noise ratio (S/N > 400) spectra gathered with the Immersion Grating Infrared Spectrograph (IGRINS) in the H and K photometric bands, we have derived elemental abundances of two bright, well-known metal-poor halo stars: the red giant HD 122563 and the subgiant HD 140283. Since these stars have metallicities approaching [Fe/H]=−3, their absorption features are generally very weak. Neutral-species lines of Mg, Si, S and Ca are detectable, as well as those of the light odd-Z elements Na and Al. The derived IR-based abundances agree with those obtained from optical-wavelength spectra. For Mg and Si the abundances from the infrared transitions are improvements to those derived from shorter wavelength data. Many useful OH and CO lines can be detected in the IGRINS HD 122563 spectrum, from which derived O and C abundances are consistent to those obtained from the traditional [O I] and CH features. IGRINS high resolutions Hand K-band spectroscopy offers promising ways to determine more reliable abundances for additional metal-poor stars whose optical features are either not detectable, or too weak, or are based on lines with analytical difficulties.

In this paper, we report results of our near-infrared (NIR) photometric variability studies of the BL Lacertae object S5 0716+714. NIR photometric observations spread over 7 nights during our observing run April 2−9, 2007 at 1.8 meter telescope equipped with KASINICS (Korea Astronomy and Space Science Institute Near Infrared Camera System) and J, H, and Ks filters at Bohyunsan Optical Astronomy Observatory (BOAO), South Korea. We searched for intraday variability, short term variability and color variability in the BL Lac object. We have not detected any genuine intra-day variability in any of J, H, and Ks passbands in our observing run. Significant short term variability ∼ 32.6%, 20.5% and 18.2% have been detected in J, H, Ks passbands, respectively, and ∼ 11.9% in (J-H) color.