• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.427-428
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• 1996

The Struve astrometric satellite which is being developed at Pulkovo Observatory in cooperation with Krasno-yarsk Institute of Applied Mechanics, S.I. Vavilov's State Optical Institute and some others space instrumentation institutes, will produce observations of a second epoch for the Hipparcos stars. The project is devoted to maintaining the Hipparcos coordinate system as well as extending it to a density of $\approx$ 100 stars per square degree. Possibilities of submilliarcsecond accuracy of observations with single aperture on-board telescopes are discussed. Requirements to the optical scheme and to the dynamic properties of the spacecraft are formulated. CCD and microchannel plates are discussed as a focal assembly detectors.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.70.5-71
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• 2015

We present a preliminary result from a high-resolution and high signal-to-noise spectroscopic survey, providing atmospheric parameters for about 170 nearby field dwarfs in the Hipparcos catalog. Our preliminary analysis shows that when Hipparcos parallaxes are adopted, a few stars in our sample are too faint compared to main-sequence fitting distances based on our accurately measured [Fe/H]. We discuss magnitude deficits of these field stars in connection with the short Hipparcos distance to the Pleiades.

• The Bulletin of The Korean Astronomical Society
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• v.25 no.2
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• pp.90-90
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• 2000

• Journal of The Korean Astronomical Society
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• v.34 no.2
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• pp.99-109
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• 2001

In the present study we have determined the distance moduli for seven globular clusters M2, M3, Ml0, M12, NGC 2808, NGC 6229, and NGC 6752, whose metallicities are in the range -1.54 < [Fe/H] < -1.10. We have derived distances for them by the main-sequence fitting method using a sample of local subdwarfs, whose accurate parallaxes are taken from the Hipparcos Catalog. The derived distance moduli are 15.52 for M2, 14.98 for M3, 14.23 for Ml0, 14.03 for M12, 15.56 for NGC 2808, 17.34 for NGC 6229, and 13.29 for NGC 6752.

• Bulletin of the Korean Space Science Society
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• 2000.10a
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• pp.90-90
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• 2000

No Abstract, See Full Text

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.19.2-19.2
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• 2011

In 1861 Nam Byeong-Gil published a book called as "Seonggyeong" which contains a star catalogue (NBGC) with the positions, magnitudes, and star maps for 1449 stars. The NBGC lists only the traditional Chinese stars selected from "the sequel to the Qing Dynasty Star Catalogue and Star Map." To identify each star from the NBGC with modern counterpart, we correct the positions of the Hipparcos stars brighter than 6.5 mag for proper motion, then precess the coordinates to the epoch of the NBGC. For each star in the NBGC, we find the nearest counterpart in the Hipparcos Catalogue (HC). If a much brighter star is at a slightly larger angular distance, we select that star as the secure counterpart. As a result, 95.5% of the stars in the NBGC were identified. We find a very good overall agreement of our results with a previous analysis by Ahn et al. (1996, Journal of the Korean History of Science Society, vol. I). For securely identified stars, we analyse its accuracy on the basis of comparison with data from the HC. The correlation of the errors between right ascensions and declinations is significantly deviated from spherical distribution. The magnitudes recorded in the NBGC correlate well with modern values. The accuracy of position decreases slowly with magnitude. Right ascensions and declinations have error distributions with ${\sigma}$ = 2.0' for the former while the latter with ${\sigma}$ = 1.6', but with much more errors >5' than expected for a Gaussian distribution.

• Journal of Astronomy and Space Sciences
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• v.21 no.2
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• pp.73-82
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• 2004

New photometric and spectroscopic solutions of W-type overcontact binary V 417 Aql were obtained by solving the UBV light curves of Samec et al. (1997) and radial-velocity ones of Lu ＆ Rucinski (1999) with the 2003 version of the Wilson-Devinney binary code. In the light curve synthesis the light of a third-body, which Qian (2003) proposed, was considered and obtained about 2.7%, 2.2%, and 0.4% for U, B, and V bandpasses, respectively. The model with third-light is better fitted to eclipse parts than that with no third-light. Absolute dimensions of V417 Aql are determined from our solution as $M_1$= 0.53 $M_{*}$, $M_2$= 1.45 $M_{*}$, $R_1$= 0.84 $R_{*}$, and $R_2$= 1.31 $M_{*}$, and the distance to it is deduced as about 216pc. Our distance is well consistent with that (204pc) derived from Rucinski ＆ Duerbeck's (1997) relation, $M_{v}$ = $M_{v}$(log P, B-V), but is more distant than that (131$\pm$40pc) determined by the Hipparcos trigonometric parallax. The difference may result from the relatively large error of Hipparcos parallax for V 417 Aql.l.

• Journal of The Korean Astronomical Society
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• v.56 no.2
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• pp.195-199
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• 2023

This paper is written as a follow-up observations to reinterpret the radial velocity (RV) of HD 36384, where the existence of planetary systems is known to be ambiguous. In giants, it is, in general, difficult to distinguish the signals of planetary companions from those of stellar activities. Thus, known exoplanetary giant hosts are relatively rare. We, for many years, have obtained RV data in evolved stars using the high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at the Bohyunsan Optical Astronomy Observatory (BOAO). Here, we report the results of RV variations in the M giant HD 36384. We have found two significant periods of 586 d and 490 d. Considering the orbital stability, it is impossible to have two planets at so close orbits. To determine the nature of the RV variability variations, we analyze the HIPPARCOS photometric data, some indicators of stellar activities, and line profiles. A significant period of 580 d was revealed in the HIPPARCOS photometry. H_α EW variations also show a meaningful period of 582 d. Thus, the period of 586 d may be closely related to the rotational modulations and/or stellar pulsations. On the other hand, the other significant period of 490 d is interpreted as the result of the orbiting companion. Our orbital fit suggests that the companion was a planetary mass of 6.6 M_J and is located at 1.3 AU from the host.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.100.1-100.1
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• 2012

Lunar limb profiles are needed for analyses of lunar occultations and solar eclipses. The lunar limb profile data by C.B. Watts (1963) have been used for such analyses, but it has been found that there are many kinds of errors in the data by Watts, which seriously affected the results obtained from the analyses of the observations. Recently very precise lunar topographic data were obtained by the Japanese lunar explorer Kaguya and NASA's Lunar Reconnaissance Orbiter. I obtained lunar limb profiles for any lunar librations from them. I will show how well the lunar limb profiles fit to observed ones from lunar grazing occultations. By combining the accurate lunar limb profiles with observations of lunar occultations we can detect errors in the Hipparcos stellar reference frame. By analyzing Baily's beads timing observations of past total and annular solar eclipses using the accurate lunar limb profiles we will be able to detect solar diameter variations.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.87-88
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• 2015

We present results of our R-band polarimetry of a bright-rimmed cloud, IC1396A (with BRC 36), associated with the H II region S131 and the cometary globule LDN 1616 to study their magnetic field geometry. The distances of these clouds have been reported to be ~ 750 pc and ~ 450 pc, respectively in the literature. The young open cluster Trumpler 37 in the vicinity of IC1396A and the high mass stars in the Orion belt near L1616 are found to be responsible for the structure of these clouds. We made polarimetry of foreground stars inferred from their distances measured by the Hipparcos satellite to subtract the foreground contribution to the observed polarization results. We discuss the optical polarimetric results and compare our findings with MHD simulations towards BRCs and CGs.