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New precise astrometric positions of Himalia in 2016-2018 based on Gaia DR2
Cheng, X.; Zhang, H. Y.; Yan, D. +5 more
Himalia is the largest irregular satellite of Jupiter. A total of 267 new observed positions of Himalia in the period 2016-2018 were collected by the 1.0 m telescopes at Yunnan Astronomical Observatory during 10 nights. Thanks to the high-quality reference catalogue Gaia DR2 and suitable processing methods for images (ie. image enhancement techniq…
CCD astrometric observations of 2017 VR12, Camillo and Midas
Su, Jie; Wang, Jian-Cheng; Zhang, Yi-Gong +2 more
We have observed three near-Earth objects (NEOs), 2017 VR12, Camillo and Midas, during 2018. The observations were made with the 1-m telescope, operated by Yunnan Observatories, over two nights. Their precise astrometric positions are derived from 989 CCD observations. The theoretical positions of asteroids are retrieved from the Jet Propulsion La…
Interplay between physics and geometry in Balmer filaments: the case of SN 1006
Raymond, J. C.; Bandiera, R.; Morlino, G. +1 more
The analysis of Balmer-dominated emission in supernova remnants is potentially a very powerful way to derive information on the shock structure, on the physical conditions of the ambient medium and on the cosmic ray acceleration efficiency. However, the outcome of models developed in plane-parallel geometry is usually not easily comparable with th…
CCD Measurements of Double and Multiple Stars at ASV and NAO Rozhen in 2017 and 2018
Cvetković, Zorica; Pavlović, Rade; Boeva, Svetlana
We give the results of CCD observations for 789 double or multiple stars obtained during 2017 and 2018. These observations were carried out at both the Serbian Astronomical Station on the mountain of Vidojevica (ASV) and the Bulgarian National Astronomical Observatory at Rozhen (NAOR). They were performed using three telescopes, the 1.4 and 0.6 m …
X-Ray Spectral Evolution of PSR J2032+4127 during the 2017 Periastron Passage
Kong, A. K. H.; Tam, P. H. T.; Cui, Y. +3 more
We report X-ray data analysis results obtained from Chandra, XMM-Newton, Nuclear Spectroscopic Telescope Array Mission (NuSTAR), and Swift observations of PSR J2032+4127 taken before, during, and after the periastron on 2017 November 13. We found the first clear evidence of a change in the X-ray spectral index over the passage period, thanks to a …
Infrequent Occurrence of Significant Linear Polarization in Hα Solar Flares
Hanaoka, Yoichiro; Kawate, Tomoko
We performed statistical and event studies of linear polarization in the Hα line during solar flares. The statistical study revealed that, among 71 Hα flares analyzed, including 64 GOES flares, only one event shows significant linear polarization signals. Such an infrequent occurrence of significant linear polarization in solar flares is consisten…
Characteristics of SEP Events and Their Solar Origin During the Evolution of Active Region NOAA 10069
Myagkova, I. N.; Kashapova, L. K.; Miteva, R. +1 more
We present the results of a comparative analysis of the properties of a series of successive solar flares, which occurred in active region (AR) 10069 in August 2002, and the associated solar energetic particle (SEP) events. The active region was extremely flare productive during its evolution. The solar flare characteristics are based on X-ray and…
Deep late-time observations of the supernova impostors SN 1954J and SN 1961V
Kochanek, C. S.; Adams, S. M.; Patton, Rachel A.
SN 1954J in NGC 2403 and SN 1961V in NGC 1058 were two luminous transients whose definitive classification as either non-terminal eruptions or supernovae remains elusive. A critical question is whether a surviving star can be significantly obscured by dust formed from material ejected during the transient. We use three lines of argument to show th…
Spatial and Genetic Relationships of Groove Belts, Rift Zones, and Lobate Plains on Venus
Guseva, E. N.
Relationships of two types of extensional zones formed on the surface of Venus in different periods of geologic history—older groove belts and younger rift zones—have been analyzed. Rift zones are less abundant by area than groove belts on the surface of Venus. They are systematically more extensive than groove belts and characterized by contrast …
A Dual Black Hole Associated with Obscured and Unobscured AGNs: CXO J101527.2+625911
Kim, D. -C.; Momjian, E.; Kim, Minjin +6 more
We report the results of an investigation to determine the nature of the offset active galactic nucleus (AGN) found in the source CXO J101527.2+625911. Hubble Space Telescope and Chandra X-ray observatory data have suggested that the offset AGN, which has an angular separation of only 0.″26 from the center of the host galaxy, is a recoiled superma…