Results 81 to 90 of about 7,595 (254)

Radio Astrometry towards the Nearby Universe with the SKA [PDF]

arXiv, 2016
This chapter summarizes radio astrometry in relation to current very long baseline interferometry (VLBI) projects and describes its perspectives with the SKA. The scientific goals of the astrometry with the SKA have been discussed in the international and Japanese communities of researchers, whose major issues are shown here.
arxiv  

The Winchcombe fireball—That lucky survivor

Meteoritics &Planetary Science, Volume 59, Issue 5, Page 927-947, May 2024.
Abstract On February 28, 2021, a fireball dropped ∼0.6 kg of recovered CM2 carbonaceous chondrite meteorites in South‐West England near the town of Winchcombe. We reconstruct the fireball's atmospheric trajectory, light curve, fragmentation behavior, and pre‐atmospheric orbit from optical records contributed by five networks.
Sarah McMullan, Denis Vida, Hadrien A. R. Devillepoix, Jim Rowe, Luke Daly, Ashley J. King, Martin Cupák, Robert M. Howie, Eleanor K. Sansom, Patrick Shober, Martin C. Towner, Seamus Anderson, Luke McFadden, Jana Horák, Andrew R. D. Smedley, Katherine H. Joy, Alan Shuttleworth, Francois Colas, Brigitte Zanda, Áine C. O'Brien, Ian McMullan, Clive Shaw, Adam Suttle, Martin D. Suttle, John S. Young, Peter Campbell‐Burns, Richard Kacerek, Richard Bassom, Steve Bosley, Richard Fleet, Dave Jones, Mark McIntyre, Nick James, Derek Robson, Paul Dickinson, Philip A. Bland, Gareth S. Collins   +36 more
wiley   +1 more source

Direct-imaging Discovery of a Substellar Companion Orbiting the Accelerating Variable Star HIP 39017

The Astronomical Journal
We present the direct-imaging discovery of a substellar companion (a massive planet or low-mass brown dwarf) to the young, γ Doradus ( γ Dor)-type variable star HIP 39017 (HD 65526). The companion’s SCExAO/CHARIS JHK (1.1–2.4 μ m) spectrum and Keck/NIRC2
Taylor L. Tobin, Thayne Currie, Yiting Li, Jeffrey Chilcote, Timothy D. Brandt, Brianna Lacy, Masayuki Kuzuhara, Maria Vincent, Mona El Morsy, Vincent Deo, Jonathan P. Williams, Olivier Guyon, Julien Lozi, Sebastien Vievard, Nour Skaf, Kyohoon Ahn, Tyler Groff, N. Jeremy Kasdin, Taichi Uyama, Motohide Tamura, Aidan Gibbs, Briley L. Lewis, Rachel Bowens-Rubin, Maïssa Salama, Qier An, Minghan Chen   +25 more
doaj   +1 more source

ASTROMETRY OF Χ AND H PERSEI BASED ON PROCESSING OF DIGITIZED PLATES OF ARCHIVE OF THE ASTRONOMICAL INSTITUTE OF THE ACADEMY OF SCIENCES OF THE REPUBLIC OF UZBEKISTAN

Odessa Astronomical Publications, 2014
Work is done  with Epson Expression 10000XL scanner  of  Astronomical Institute  (AI)  of theAcademyofSciencesofUzbekistan. The plates were exposed  with theNormalastrograph (D/F = 330mm / 3467mm, M = 59.56"/mm). The  digitization  of  plates with(16x16)
M. M. Muminov, Q. X. Yuldoshev, Sh. A. Ehgamberdiev, B. B. Kahharov, V. N. Andruk, Yu. I. Protsyuk   +5 more
doaj   +1 more source

Cross‐Polarization Gain Calibration of Linearly Polarized VLBI Antennas by Observations of 4C 39.25

Radio Science, Volume 59, Issue 4, April 2024.
Abstract Radio telescopes with dual linearly polarized feeds regularly participate in Very Long Baseline Interferometry. One example is the VLBI Global Observing System (VGOS), which is employed for high‐precision geodesy and astrometry. In order to achieve the maximum signal‐to‐noise ratio, the visibilities of all four polarization products are ...
F. Jaron, I. Martí‐Vidal, M. Schartner, J. González‐García, E. Albentosa‐Ruiz, S. Bernhart, J. Böhm, J. Gruber, S. Modiri, A. Nothnagel, V. Pérez‐Díez, T. Savolainen, B. Soja, E. Varenius, M. H. Xu   +14 more
wiley   +1 more source

VLBI Astrometry [PDF]

arXiv, 2003
VLBI astrometry allows coordinates of celestial radio sources to be determined with submilliarcsecond accuracy. In particular, with differential VLBI astrometry, the standard errors of relative positions and proper motions can be as small as 10 microarcseconds and 10 microarcseconds per year, respectively. I will review astrometric observations of AGN,
arxiv  

Sub-Microarcsecond Astrometry with SIM-Lite: A Testbed-based Performance Assessment [PDF]

, 2008
SIM-Lite is an astrometric interferometer being designed for sub-microarcsecond astrometry, with a wide range of applications from searches for Earth-analogs to determining the distribution of dark matter. SIM-Lite measurements can be limited by random and systematic errors, as well as astrophysical noise.
arxiv   +1 more source

Prototype System for Unmanned Reference Point Determination at the Sub‐Millimeter Level

Earth and Space Science, Volume 11, Issue 2, February 2024.
Abstract The determination of reference points for telescopes is crucial for obtaining the local‐tie vector for a multi‐technology co‐located station. Traditional methods suffer from labor‐intensive fieldwork, long execution cycles, and systematic errors due to the incident angle of the total station's laser beam on the prism. In this paper, we propose
Zhibin Zhang, Zhikang Wang, Xiaohui Ma, Zhengxiong Sun, Dezhen Xu, Chengli Huang, Guangli Wang, Zhaoxiang Qi   +7 more
wiley   +1 more source

The Global Shape, Gravity Field, and Libration of Enceladus

Journal of Geophysical Research: Planets, Volume 129, Issue 1, January 2024.
Abstract In order to improve our understanding of the interior structure of Saturn's small moon Enceladus, we reanalyze radiometric tracking and onboard imaging data acquired by the Cassini spacecraft during close encounters with the moon. We compute the global shape, gravity field, and rotational parameters of Enceladus in a reference frame consistent
R. S. Park, N. Mastrodemos, R. A. Jacobson, A. Berne, A. T. Vaughan, D. J. Hemingway, E. J. Leonard, J. C. Castillo‐Rogez, C. S. Cockell, J. T. Keane, A. S. Konopliv, F. Nimmo, J. E. Riedel, M. Simons, S. Vance   +14 more
wiley   +1 more source

High Definition Astrometry [PDF]

arXiv, 2019
High Definition Astrometry (0.1 - 1.0 micro-arcseconds) will open a new window into neighboring planetary systems. For the first time, the realm of temperate terrestrial worlds will be explored. This includes Earth Analogs, thereby allowing the value of eta-Earth to be directly determined, without resort to extrapolation.
arxiv