Results 51 to 60 of about 4,915 (213)

Reassessing the Relationship Between Meteor Radio Afterglows and Optical Persistent Trains

Journal of Geophysical Research: Space Physics, Volume 130, Issue 9, September 2025.
Abstract Meteor radio afterglows (MRAs) and optical persistent trains (PTs) are two types of long‐lived phenomena which are occasionally observed following the occurrence of a meteor. Both phenomena are thought to be produced by intrinsic emission mechanisms; PTs have been associated with chemiluminescent reactions between meteoric metals and ...
L. E. Cordonnier, K. S. Obenberger, G. B. Taylor, J. M. Holmes, J. Dowell, D. Vida   +5 more
wiley   +1 more source

The Power of (Near) Simultaneous Multi-Frequency Observations for mm-VLBI and Astrometry

Galaxies, 2017
Simultaneous or near-simultaneous observations at multiple frequency bands have the potential to overcome the fundamental limitation imposed by the atmospheric propagation in mm-VLBI observations.
María J. Rioja, Richard Dodson, José L. Gómez, Sol N. Molina, Taehyun Jung, Bong Won Sohn   +5 more
doaj   +1 more source

Overview of the Observing System and Initial Scientific Accomplishments of the East Asian VLBI Network (EAVN)

Galaxies, 2022
The East Asian VLBI Network (EAVN) is an international VLBI facility in East Asia and is operated under mutual collaboration between East Asian countries, as well as part of Southeast Asian and European countries.
Kazunori Akiyama, Juan-Carlos Algaba, Tao An, Keiichi Asada, Kitiyanee Asanok, Do-Young Byun, Thanapol Chanapote, Wen Chen, Zhong Chen, Xiaopeng Cheng, James O. Chibueze, Ilje Cho, Se-Hyung Cho, Hyun-Soo Chung, Lang Cui, Yuzhu Cui, Akihiro Doi, Jian Dong, Kenta Fujisawa, Wei Gou, Wen Guo, Kazuhiro Hada, Yoshiaki Hagiwara, Tomoya Hirota, Jeffrey A. Hodgson, Mareki Honma, Hiroshi Imai, Phrudth Jaroenjittichai, Wu Jiang, Yongbin Jiang, Yongchen Jiang, Takaaki Jike, Dong-Kyu Jung, Taehyun Jung, Noriyuki Kawaguchi, Dong-Jin Kim, Hyo-Ryoung Kim, Jaeheon Kim, Jeong-Sook Kim, Kee-Tae Kim, Soon-Wook Kim, Motoki Kino, Hideyuki Kobayashi, Shoko Koyama, Busaba H. Kramer, Jee-Won Lee, Jeong Ae Lee, Sang-Sung Lee, Sang Won Lee, Bin Li, Guanghui Li, Xiaofei Li, Zhixuan Li, Qinghui Liu, Xiang Liu, Ru-Sen Lu, Kazuhito Motogi, Masanori Nakamura, Kotaro Niinuma, Chungsik Oh, Hongjong Oh, Junghwan Oh, Se-Jin Oh, Tomoaki Oyama, Jongho Park, Saran Poshyachinda, Hyunwook Ro, Duk-Gyoo Roh, Wiphu Rujopakarn, Nobuyuki Sakai, Satoko Sawada-Satoh, Zhi-Qiang Shen, Katsunori M. Shibata, Bong Won Sohn, Boonrucksar Soonthornthum, Koichiro Sugiyama, Yunxia Sun, Mieko Takamura, Yoshihiro Tanabe, Fumie Tazaki, Sascha Trippe, Kiyoaki Wajima, Jinqing Wang, Na Wang, Shiqiang Wang, Xuezheng Wang, Bo Xia, Shuangjing Xu, Hao Yan, Wenjun Yang, Jae-Hwan Yeom, Kunwoo Yi, Sang-Oh Yi, Yoshinori Yonekura, Hasu Yoon, Linfeng Yu, Jianping Yuan, Youngjoo Yun, Bo Zhang, Hua Zhang, Yingkang Zhang, Guang-Yao Zhao, Rongbing Zhao, Weiye Zhong, on behalf of the East Asian VLBI Network Collaboration   +104 more
doaj   +1 more source

Astrometry of Circumstellar Masers [PDF]

, 2003
8 pages, 2 figures, to appear in "Mass-losing Stars and their Circumstellar Matter", eds Y. Nakada & M.
van Langevelde, H. J., Vlemmings, W. H. T.   +1 more
openaire   +2 more sources

Speckle Observations With PISCO in Calern (France): II. Astrometric Measurements of Visual Double Stars in 2017–2018 and New or Revised Orbits for A1913 AB, A1710, COU1394, BU1185, A122, A570, HU577, COU812, HU332, A2095 AB, and A884

Astronomische Nachrichten, Volume 346, Issue 6, July 2025.
ABSTRACT We present relative astrometric measurements of visual double stars, made in 2017–2018 with the speckle camera PISCO at the 1‐m Epsilon telescope of the C2PU facility (Observatoire de la Côte d'Azur, Calern site). Our observing list contains orbital couples as well as double stars whose motion is still uncertain.
M. Scardia, J.‐L. Prieur, J.‐P. Rivet, D. Vernet, E. Aristidi, J. F. Ling, L. Piccotti, L. Pansecchi, R. W. Argyle, L. Abe, P. Bendjoya, L. Maccarini   +11 more
wiley   +1 more source

Overview and Status of the International Celestial Reference Frame as Realized by VLBI

Universe, 2022
Accurate measurement of angular positions on the sky requires a well-defined system of reference that is realized with accessible objects. The purpose of this study is to review the international standard realization of such a system, the International ...
Aletha de Witt, Patrick Charlot, David Gordon, Christopher S. Jacobs   +3 more
doaj   +1 more source

Uncertainties in Ground‐Based Visual Double Star Measures—II Accuracy of Measures

Astronomische Nachrichten, Volume 346, Issue 6, July 2025.
ABSTRACT Letchford and White 2025, Paper I, determined the uncertainties in ground‐based historic measures of double stars. In this paper, the accuracy of 26,205 ground‐based measures of 857 visual double stars, made since ∼$$ \sim $$1780, is determined relative to space‐based measures based on positions and proper motion from the HIPPARCOS (via ASCC ...
Graeme L. White, Roderick R. Letchford
wiley   +1 more source

COMMISSION 8: ASTROMETRY [PDF]

Proceedings of the International Astronomical Union, 2011
Gaia is continuing well with its development and construction and is expected to achieve parallax accuracies of about 10 to 300 μas for 6 to 20 mag. It is scheduled to launch in 2013. The ICRF2 was adopted by the IAU in 2009 as the new fundamental celestial reference frame.
Evans, Dafydd W., Zacharias, Norbert, Kumkova, Irina, Andrei, Alexandre Humberto, Brown, Anthony, Gouda, Naoteru, Popescu, Petre, Souchay, Jean, Unwin, Stephen C., Zhu, Z.   +9 more
openaire   +2 more sources

Deep Space Network Radio Science and Ground‐Based Planetary Radar in the Next Decade

Radio Science, Volume 60, Issue 7, July 2025.
Abstract The Deep Space Network (DSN) has been a core operational element of NASA's crewed and robotic exploration of the Solar System since the early 1960s. The primary role of the DSN has been to acquire telemetry and navigation data, but over the years, its radiometric and radar capabilities have expanded to form a system for obtaining unique ...
R. S. Park, J. E. Riedel, N. Rodriguez‐Alvarez, M. Brozovic, L. A. M. Benner, P. Vergados, D. Buccino, C. S. Jacobs, L. S. Locke, S. W. Asmar, R. Castano, T. J. W. Lazio, J. Jao, C. Lee   +13 more
wiley   +1 more source

Corrections to the Hipparcos proper motions in declination for 807 stars [PDF]

Serbian Astronomical Journal, 2008
We used the data on latitude variations obtained from observations with 10 classical photographic zenith tubes (PZT) in order to improve the Hipparcos proper motions in declinations µδ for 807 stars.
Damljanović G., Pejović N.
doaj   +1 more source