• 천문학회보
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• 제43권2호
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• pp.29.2-29.2
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• 2018

Korean Neutrino Observatory (KNO) aims to make important discoveries in particle physics and astronomy by building a gigantic neutrino telescope consisting of 260 kiloton water and 40,000 20 inch photomultiplier tubes. Using J-PARC neutrino beam, leptonic CP violation (CPV) could be discovered if the CP is maximally violated, and neutrino mass ordering is guaranteed to be determined with more than 6 sigma for any CPV value. As a neutrino telescope, solar and Supernova burst/relic neutrinos could be studied very precisely. Indirect dark matter search sensitivity is improved by 3 to 4 times than that of Super Kamiokande. There are several candidate sites in Korea and especially Mt. Bisul and Mt. Bohyun are very promising according to our site survey. In this talk, an overview of the KNO is presented.

• 천문학회지
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• 제47권2호
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• pp.43-47
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• 2014

Many advanced ground-based solar telescopes improve the spatial resolution of observation images using an adaptive optics (AO) system. As any AO correction remains only partial, it is necessary to use post-processing image reconstruction techniques such as speckle masking or shift-and-add (SAA) to reconstruct a high-spatial-resolution image from atmospherically degraded solar images. In the New Vacuum Solar Telescope (NVST), the spatial resolution in solar images is improved by frame selection and SAA. In order to overcome the burden of massive speckle data processing, we investigate the possibility of using the speckle reconstruction program in a real-time application at the telescope site. The code has been written in the C programming language and optimized for parallel processing in a multi-processor environment. We analyze the scalability of the code to identify possible bottlenecks, and we conclude that the presented code is capable of being run in real-time reconstruction applications at NVST and future large aperture solar telescopes if care is taken that the multi-processor environment has low latencies between the computation nodes.

• 천문학논총
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• 제28권1호
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• pp.1-6
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• 2013

Real-time data reduction pipeline for the Korea Microlensing Telescope Network (KMTNet) was developed by Korea Astronomy and Space Science Institute (KASI). The main goal of the data reduction pipeline is to find variable objects and to record their light variation from the large amount of observation data of about 200 GB per night per site. To achieve the goal we adopt three strategic implementations: precision pointing of telescope using the cross correlation correction for target fields, realtime data transferring using kernel-level file handling and high speed network, and segment data processing architecture using the Sun-Grid engine. We tested performance of the pipeline using simulated data which represent the similar circumstance to CTIO (Cerro Tololo Inter-American Observatory), and we have found that it takes about eight hours for whole processing of one-night data. Therefore we conclude that the pipeline works without problem in real-time if the network speed is high enough, e.g., as high as in CTIO.

• 천문학논총
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• 제30권2호
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• pp.699-701
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• 2015

The high plateaus in west China may provide suitable sites for astronomical observations with the institute's middle-range telescopes and possibly with larger telescopes. Under China-Japan collaborations for site survey in west China, we have been conducting searches for good sites and monitoring their characteristics over several years. As recent results of our site survey show, sites in west Tibet are revealed with a high possibility of good astronomical observations. Weather characteristics at Gar in Ali, Tibet, show its high clear-sky ratios, especially in winter, comparable to Mauna Kea, Hawaii. But it has some wind problem in winter, where stronger wind speeds, over 20m/sec, occur frequently even though the sky is clear. To find calmer sites, we have conducted numerical simulations for the Ali area using the Japan Meteorological Agency NonHydrostatic Model. We have found another site, named ZoZo Hill, near Gar. We will continue to monitor the Gar site to clarify weather characteristics over the whole year and hopefully start to negotiate for site monitoring at ZoZo Hill this year.

• 천문학논총
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• 제11권1호
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• pp.177-196
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• 1996

We have investigated the astronomical observational environments at the Choejung-san GEODSS site which is located at the south of Taegu, Korea. As a part of the investigation, seeing and night sky brightness were measured outside nearby the GEODSS site using the Celestron 8-inch portable reflector with $192{\times}165$ pixels Lynxx CCD camera during the period of December 1994 to April 1996. The average seeing values of 4.8 arcsecond in B filter and 5.1 arcsecond in V filter were determined using the IRAF software. These values might be overestimated and would be reduced by at least 1 arc second in both filters if they were measured by more stable telescope system with solid mount and under a dome. We also compare the average seeing value at the GEODSS site with those at three other observatories, the Bohyunsan Optical Astronomy Observatory, the Sobaeksan Optical Astronomy Observatory, and the Seoul National University Observatory, for justification of the above guess. Unfortunately the night sky brightness measurement was not successful mainly due to the short exposure time. The utilizing plan of the GEOSS site is discussed based on the average seeing value, naked-eye sky brightness measurement, analysis of the existing thirty-year weather data and twenty-year urban planning of the metropolitan Taegu city for the year of 2016.

• Journal of Astronomy and Space Sciences
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• 제30권3호
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• pp.127-132
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• 2013

Here we review the effort of Fermi Asian Network (FAN) in exploring the supernova remnants (SNRs) with state-of-art high energy observatories, including Fermi Gamma-ray Space Telescope and Chandra X-ray Observatory, in the period of 2011- 2012. Utilizing the data from Fermi LAT, we have discovered the GeV emission at the position of the Galactic SNR Kes 17 which provides evidence for the hadronic acceleration. Our study also sheds light on the propagation of cosmic rays from their acceleration site to the intersteller medium. We have also launched an identification campaign of SNR candidates in the Milky Way, in which a new SNR G308.3-1.4 have been uncovered with our Chandra observation. Apart from the remnant, we have also discovered an associated compact object at its center. The multiwavelength properties of this X-ray source suggest it can possibly be the compact binary that survived a supernova explosion.

• 천문학논총
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• 제30권1호
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• pp.31-38
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• 2015

We develop a real-time data transfer system for the Korea Microlensing Telescope Network (KMTNet) photometry data and test whether it is suitable for Korea Astronomy and Space Science Institute (KASI) and three different observatories, which are Cerro Tololo Inter-Ameriacan Observatory (CTIO) in Chile, Siding Springs Observatory (SSO) in Australia, and South African Astronomical Observatory (SAAO) in South Africa. For this test, we use a high speed global network being dedicated for researches. From the test, we obtain that the elapsed times between KASI and each three observatories, CTIO, SSO, and SAAO to transfer 650 MB of data are 99.0, 9.2, 119.0 seconds, respectively. This means that the system can be used for the real-time data processing of KMTNet.

• 천문학회지
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• 제29권spc1호
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• pp.205-208
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• 1996

Multi-wavelength observing has been particularly fruitful in cool star research. There have been some well-observed examples, eg AB Dor, though ambiguity remains. This raises issues of data information content and model parameter determinacy, which are examined firstly in an optical context. We then widen the discussion to show how multi-site and multi-wavelength data can be combined to point to better constrained models. Particular cases, involving near-simultaneous radiometry and photometry, are discussed to clarify such modelling.

• 천문학논총
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• 제19권1호
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• pp.55-63
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• 2004

Observation environment of the Bohyunsan Optical Astronomy Observatory(BOAO) has been examined using various statistical data including real observation times versus allocated times and seeing statistics. The data have been collected from the observation logs of the 1.8m telescope in the period 1998 - 2004. New criteria have been set up to calculate a more realistic observation efficiency of the observatory. The new statistical analysis based on the new criteria gives the overall observation efficiency of BOAO as $38.6\%$, that is equivalent to 115.8 observable nights out of 300 allocatable nights. The seeing statistics shows that the mean seeing measured at the focal images is 2".3. The present study of the observation environment of BOAO suggests that differential photometry and spectroscopy should be preferred modes of observation to maximize the productivity of BOAO.

• 천문학회보
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• 제35권1호
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• pp.58.2-58.2
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• 2010

L1251B, which was revealed as a small group of protostars by the Spitzer Space Telescope (SST), presents a great site of studying chemical evolution in gas and ice as well as various dynamical processes associated with star formation (infall, rotation, and outflow). We have mapped L1251B with the Infrared Spectrograph (IRS) aboard the SST to study the chemical distribution in the phases of gas and ice and the dynamical feature related to shock in the region. Various atomic lines and the $H_2$ pure rotational lines, which trace different shock velocities, were detected. In addition, the distribution of the water and $CO_2$ ices hints variety of the ice desorption mechanism in L1251B.