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        검색결과 76

        24.
        2019.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We derive the geometric albedo of a near-Earth asteroid, (4179) Toutatis, to investigate its surface physical conditions. The asteroid has been studied rigorously not only via ground-based photometric, spectrometric, polarimetric, and radar observations but also via in situ observation by the Chinese Chang'e-2 space probe; however, its geometric albedo is not well understood. We conducted V-band photometric observations when the asteroid was at opposition in April 2018 using the three telescopes in the southern hemisphere that compose the Korea Microlensing Telescope Network (KMTNet). The observed time-variable cross section was corrected using the radar shape model. We nd that Toutatis has a geometric albedo pV = 0:185+0:045 -0:039, which is typical of S-type asteroids. We compare the geometric albedo with archival polarimetric data and further nd that the polarimetric slope{albedo law provides a reliable estimate for the albedo of this S-type asteroid. The thermal infrared observation also produced similar results if the size of the asteroid is updated to match the results from Chang'e-2. We conjecture that the surface of Toutatis is covered with grains smaller than that of the near-Sun asteroids including (1566) Icarus and (3200) Phaethon.
        4,300원
        29.
        2018.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The DEEP-South (the Deep Ecliptic Patrol of the Southern Sky) photometric census of small Solar System bodies produces massive time-series data of variable, transient or moving objects as a by- product. To fully investigate unexplored variable phenomena, we present an application of multi-aperture photometry and FastBit indexing techniques for faster access to a portion of the DEEP-South year-one data. Our new pipeline is designed to perform automated point source detection, robust high-precision photometry and calibration of non-crowded fields which have overlap with previously surveyed areas. In this paper, we show some examples of catalog-based variability searches to find new variable stars and to recover targeted asteroids. We discover 21 new periodic variables with period ranging between 0.1 and 31 days, including four eclipsing binary systems (detached, over-contact, and ellipsoidal variables), one white dwarf/M dwarf pair candidate, and rotating variable stars. We also recover astrometry (< ±1–2 arcsec level accuracy) and photometry of two targeted near-earth asteroids, 2006 DZ169 and 1996 SK, along with the small- (0.12 mag) and relatively large-amplitude (0.5 mag) variations of their dominant rotational signals in R-band.
        4,600원
        38.
        2017.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We conduct BVRI and R band photometric observations of asteroid (5247) Krylov from January 2016 to April 2016 for 51 nights using the Korea Microlensing Telescope Network (KMTNet). The color indices of (5247) Krylov at the light curve maxima are determined as B - V = 0:841  0:035, V -R = 0:4180:031, and V -I = 0:8710:031 where the phase angle is 14.1◦. They are acquired after the standardization of BVRI instrumental measurements using the ensemble normalization technique. Based on the color indices, (5247) Krylov is classi ed as a S-type asteroid. Double periods, that is, a primary period P1 = 82:188  0:013 h and a secondary period P2 = 67:13  0:20 h are identi ed from period searches of its R band light curve. The light curve phases with P1 and this indicate that it is a typical Non-Principal Axis (NPA) asteroid. We discuss the possible causes of its NPA rotation.
        4,000원
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