• Title/Summary/Keyword: asteroids

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Survey of Solar System Objects using KMTNet

  • Yang, Hongu;Ishiguro, Masateru;Lee, Hee-Jae;JeongAhn, Youngmin;Moon, Hong-Kyu;Choi, Young-Jun
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.63.1-63.1
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    • 2019
  • Solar system small bodies are unusual objects in astronomical survey data in that they are moving on the celestial sphere. In addition, even in a normal status, their magnitudes are changing over time, firstly because their relative positions with respect to the Sun and Earth are continually changing, secondly because they are rotating bodies with non-spherical shapes. Furthermore, some of them might exhibit unexpected activities, which could be caused by mass ejection or disintegration. Detections and observations of such activities are challenging due to their abrupt nature. Therefore, continuous monitoring observations of large number of Solar system small bodies are required to systematically obtain detailed/transient information about them. Since 2018/2019 winter, we have launched a new project using Korea Microlensing Telescope Network (KMTNet) for detecting such transient phenomena of Solar system objects. Our main goal is to monitor the magnitudes and detect sudden brightness changes. We also plan to discover interesting new objects, and monitor rotational brightness oscillations of asteroids. We intend to monitor the magnitudes of ~ 20,000 known Solar system small bodies per night, and acquire lightcurves of ~ 1,000 asteroids.

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Observation of Three Variable Stars and an Asteroid Using Small Telescopes in the United Arab Emirates (UAE)

  • Mohammad Sh. Odeh;Mashhoor Al-Wardat
    • Journal of Astronomy and Space Sciences
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    • v.40 no.1
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    • pp.19-27
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    • 2023
  • We present the results of using small telescopes in the United Arab Emirates (UAE) for observing variable stars and asteroids. Two telescopes, namely, 5" apochromatic refractor and 14" Schmidt-Cassegrain, at Al-Khatim Observatory (M44) were used for the observations. The targets were the three variable stars RR GEM, AG LMi, and DL CMi and the asteroid 22 Kalliope. We found a good consistency between our light curves and published ones for the calibration targets, i.e., the asteroid 22 Kalliope and the variable star RR GEM. According to previous studies, AG LMi has two suggested periods, 16.3 hours and 32.62 hours. Our results clearly confirm the second one, with a period of 32.6175 hours. The star DL CMi has several suggested periods as per previous studies, such as 4.0173 days, 1.9606 days, and 2.0086 days. Our observations confirm the first one, with a period of 4.0159 days. These results demonstrate the effectiveness of using small telescopes for observing variable stars and asteroids. This work provides some recommendations on using small telescopes for such observations.

DEEP-South: 2nd phase of observations for small Solar System bodies

  • Kim, Myung-Jin;Choi, Young-Jun;Yang, Hongu;Lee, Hee-Jae;Kim, Dong-Heun;JeongAhn, Youngmin;Roh, Dong-Goo;Moon, Hong-Kyu;Chang, Chan-Kao;Durech, Josef;Broz, Miroslav;Hanus, Josef;Masiero, Joseph;Mainzer, Amy;Bauer, James
    • The Bulletin of The Korean Astronomical Society
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    • v.45 no.1
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    • pp.46.1-46.1
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    • 2020
  • DEEP-South (DEep Ecliptic Patrol of the Southern Sky) team will start the 2nd phase of KMTNet observation in Oct 2020. The DEEP-South observation mainly consists of three survey modes: (1) Activity survey (AS) that aims at finding active phenomena of small Solar System bodies. (2) Light curve survey (LS) targets to discover and characterize light variations of asteroids. And (3) Deep drilling survey (DS) focuses on the objects beyond the orbit of Jupiter (Centaurus and trans-Neptunian objects) as well as near Earth asteroids. For asteroid family (AF) studies and target of opportunity (TO) observations for urgent photometric follow-up, targeted mode will also be used. DEEP-South team is awarded 7.0% of the telescope time at each site every year from Oct 2020 to Sep 2023 in the 2nd phase of KMTNet operation which corresponds to about 75 full nights a year for the network. In this presentation, we will introduce our survey strategy and observation plan.

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Polarimetry of solar system small bodies using the Seoul National University 61cm telescope and TRIPOL

  • Jin, Sunho;Ishiguro, Masateru;Kwon, Yuna Grace;Geem, Jooyeon;Bach, Yoonsoo P.;Seo, Jinguk;Sasago, Hiroshi;Sato, Shuji
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.64.2-64.2
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    • 2019
  • It is known that lights scattered by comets and asteroids are partially polarized. From polarimetric observations of those objects, we can investigate physical properties, such as albedos, sizes of cometary dust particles and regolith of asteroids. Since the polarization degrees of those objects highly depend on their phase angles (Sun-object-observer's angles), long-term monitoring observations are required. Moreover, comets show unforeseeable activations (i.e., outbursts) which need follow-up observations to understand the mechanism. In order to realize such monitoring and transient observations, we installed the Triple-Range Imager and POLarimeter (TRIPOL) on the 61cm telescope of Seoul National University (Hereafter, SNU) Gwanak campus. With this combination, we can obtain g', r', i' bands photopolarimetric images simultaneously with $8.0^{\prime}{\times}8.0^{\prime}$ field of view and pixel resolution of 0.94" pixel-1. Here, we make a presentation regarding the photometric and polarimetric performances of TRIPOL on the SNU 61cm telescope. In addition, we introduce initial polarimetric results of asteroid and comets with the instruments. First, we determine the limiting magnitudes (defined as magnitudes for S/N=5) of $15.17{\pm}0.06$ (g'-band), $15.68{\pm}0.01$ (r'-band), $16.24{\pm}0.03$ (I'-band), respectively, with total 240-seconds exposure (four 60-seconds exposure images, each was taken at different rotation angle for the half-wave plate). Second, we found that the instrumental polarization is negligibly small, ($-0.32{\pm}0.04%$ in the g', $-0.36{\pm}0.05%$ in the r' and $-0.21{\pm}0.04%$ in the i'-bands), while the polarization efficiencies are large enough to maximize the performance (i.e., $97.52{\pm}0.03%$ in the g', $98.83{\pm}0.02%$ in the r' and $99.15{\pm}0.02%$ in the i'-bands). With the instruments, we made observations of three Jupiter-family comets, 21P/Giacobini-Zinner, 38P/Stephan-Oterma, and 46P/Wirtanen and plan to observe one near-Earth asteroid, (433) Eros, on a trial basis. Especially for comets, we discriminate signals from dust and gas to eliminate gas contamination, which are known to change observed degree of linear polarization, using multi-band images. We confirm that the phase angle dependency of these comets are consistent with previous observations, probably because polarimetric property of Jupiter-family comets are broadly homogeneous unlike asteroids. We will also describe future observation plans using TRIPOL and SNU 61cm telescope.

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WSO-UV progress and SODA project

  • Sachkov, Mikhail
    • The Bulletin of The Korean Astronomical Society
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    • v.40 no.2
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    • pp.39.2-39.2
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    • 2015
  • The World Space Observatory Ultraviolet (WSO-UV) is the space mission that will grant access to the UV range in the post Hubble epoch. WSO-UV is equipped with instrumentation for imaging and spectroscopy and it is fully devoted to UV astronomy. In this talk, we outline the WSO-UV mission model and present the current status of the project. Also, the NEO observing mission SODA (System of Observation of Day-time Asteroids) is also presented.

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Echinodermata from Chindo Island, Korea

  • Shin, Sook
    • Animal Systematics, Evolution and Diversity
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    • v.11 no.1
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    • pp.115-124
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    • 1995
  • Twenty-two species of Echinodermata collected from 11 localities in Chindo Island, Korea in September, 1990 and July, 1994 are recorded. One asteroids, Luidia quinaria, five ophiudoids such as Astrocladus coniferus coniferus, A.c.dofleini, Ophicatis affinis, Stegophiura sladeni, Amphipholis sp., four echinoids such as Temnopleurus toreumaticus, T. hardwicki, Hemicentrotus pulcherrimus, anthoicidaris crassispina and two holothuroids such as Protankyra bidentata, Stichopus japonicus are unrecorded species by this time in Chindo Is. One asteroid species, Asterina minor is newly recorded in Korea water and its taxonomic characteristics are redescribed.

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A Newly Recorded Sea Star (Asteroidea: Valvatida) from Jejudo Island, Korea

  • Shin, Sook
    • Animal Systematics, Evolution and Diversity
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    • v.26 no.3
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    • pp.349-351
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    • 2010
  • Some asteroid specimens were collected from the subtidal zone near Gapado, Jejudo Island with fishing net on June 2010. Among them, Anseropoda petaloides (Goto, 1914) which belongs to the family Asterinidae of the order Valvatida turned out to be a new record from Korea. Morphological characters of this species collected at 130 m deep are redescribed with photographs. This species is characterized by its very thin body composed of plates imbricated into each other like scales. Twenty four asteroids are currently known from Jejudo Island, Korea.

A New Record of Sea Star (Asteroidea: Phanerozonia) from Jejudo Island, Korea

  • Shin, Sook
    • Animal Systematics, Evolution and Diversity
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    • v.23 no.2
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    • pp.251-253
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    • 2007
  • Some sea stars were collected from the coast of Seogwipo, Jejudo Island by using the fishing net at April 2003, and were identified on the basis of their morphological characteristics. Among them, Paragonaster ctenopes Sladen, 1889 belonging to family Goniasteridae, order Phanerozonia is newly recorded from Korea. Twenty two species of asteroids are reported to be distributed in the Jejudo Island of Korea.

PHOTOMETRIC STUDY OF NPA ROTATOR (5247) KRYLOV

  • Lee, Hee-Jae;Moon, Hong-Kyu;Kim, Myung-Jin;Kim, Chun-Hwey;Durech, Josef;Choi, Young-Jun;Oh, Young-Seok;Park, Jintae;Roh, Dong-Goo;Yim, Hong-Suh;Cha, Sang-Mok;Lee, Yongseok
    • Journal of The Korean Astronomical Society
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    • v.50 no.3
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    • pp.41-49
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    • 2017
  • 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 $B-V=0.841{\pm}0.035$, $V-R=0.418{\pm}0.031$, and $V-I=0.871{\pm}0.031$ where the phase angle is $14.1^{\circ}$. They are acquired after the standardization of BVRI instrumental measurements using the ensemble normalization technique. Based on the color indices, (5247) Krylov is classified as a S-type asteroid. Double periods, that is, a primary period $P_1=82.188{\pm}0.013h$ and a secondary period $P_2=67.13{\pm}0.20h$ are identified from period searches of its R band light curve. The light curve phases with $P_1$ and this indicate that it is a typical Non-Principal Axis (NPA) asteroid. We discuss the possible causes of its NPA rotation.

DEEP-South: The Progress and the Plans of the First Year

  • Moon, Hong-Kyu;Kim, Myung-Jin;Roh, Dong-Goo;Park, Jintae;Yim, Hong-Suh;Lee, Hee-Jae;Choi, Young-Jun;Oh, Young-Seok;Bae, Young-Ho
    • The Bulletin of The Korean Astronomical Society
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    • v.41 no.2
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    • pp.48.2-48.2
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    • 2016
  • The wide-field and the round-the clock operation capabilities of the KMTNet enables the discovery, astrometry and follow-up physical characterization of asteroids and comets in a most efficient way. We collectively refer to the team members, partner organizations, the dedicated software subsystem, the computing facility and research activities as Deep Ecliptic Patrol of the Southern Sky (DEEP-South). Most of the telescope time for DEEP-South is devoted to targeted photometry of Near Earth Asteroids (NEAs) to push up the number of the population with known physical properties from several percent to several dozens of percent, in the long run. We primarily adopt Johnson R-band for lightcurve study, while we employ BVI filters for taxonomic classification and detection of any possible color variations of an object at the same time. In this presentation, the progress and new findings since the last KAS meeting will be outlined. We report DEEP-South preliminary lightcurves of several dozens of NEAs obtained at three KMTNet stations during the first year runs. We also present a physical model of asteroid (5247) Krylov, the very first Non principal Axis (NPA) rotator that has been confirmed in the main belt (MB). A new asteroid taxonomic classification scheme will be introduced with an emphasis on its utility in the LSST era. The progress on the current version of automated mover detection software will also be summarized.

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