Results 61 to 70 of about 30,911 (193)
Photographic zenith tubes observations to improve HIPPARCOS proper motion in declination of some stars [PDF]
Serbian Astronomical Journal, 2005 A procedure of calculation and results of an attempt to improve proper motions in declination for some HIPPARCOS stars are presented. A long series of optical observations of these stars observed with Photographic Zenith Tubes (PZT) are used.
Damljanović Goran M.
doaj +1 more source
, 2023 An introduction to how astrometric measurements are done with long-baseline optical interferometry, in single or dual-field, and in particular with the GRAVITY instrument.
openaire +1 more source
Satellites and Small Bodies With ALMA: Insights Into Solar System Formation and Evolution
AGU Advances, Volume 6, Issue 6, December 2025.Abstract Our understanding of the formation and evolution of planetary systems has made major advances in the past decade. This progress has been driven in large part by the Atacama Large Millimeter/submillimeter Array (ALMA), which has given us an unprecedented view of solar system bodies themselves, and of the structure and chemistry of forming ...
Katherine de Kleer +3 more
wiley +1 more source
An Efficient Method for Measuring the Color of a Natural Satellite with Astrometric Applications
The Astronomical JournalThe Gaia DR3 catalog released in 2022 contains precise broadband photometry for more than one billion stars in the G , BP, and RP passbands, which is very useful for calibrating the differential color refraction (DCR) effect in ground-based observations.
X. Q. Fang, Q. Y. Peng, X. Lu, B. F. Guo
doaj +1 more source
Digitization of the Belgrade Astronomical Observatory's vertical circle observational heritage [PDF]
Serbian Astronomical Journal, 2018 The aim of the paper is to present the digitization of the results of last observations of bright stars made by the Belgrade vertical circle ASKANIA N±80118 (D = 190 mm, f = 2578 mm) at the Astronomical Observatory of Belgrade.
Šegan S., Šegan-Radonjić M.
doaj +1 more source
Relativity in Astrometry [PDF]
Symposium - International Astronomical Union, 1986 The coordinate dependence of the definition of light deflexion is discussed and the concepts of “natural” and “proper” reference frame are introduced in order to derive astrometric observables from coordinate quantities. Confusion in published formulations of VLBI data analysis is discussed in the context of the IAU definition of the coordinate time ...
openaire +1 more source
Globally Critical Infrastructure: The Unique Risks and Challenges
Risk Analysis, Volume 45, Issue 12, Page 4804-4817, December 2025.ABSTRACT Critical infrastructure is typically identified at the national level. However, disruption to certain infrastructure systems, facilities, and assets can have negative consequences for global societies. Such globally critical infrastructure entails a distinct risk profile for both countries dependent on the infrastructure, and countries that ...
Zachary Kallenborn, Henry H. Willis
wiley +1 more source
Astronomische Nachrichten, Volume 346, Issue 9, November 2025.ABSTRACT We present James Webb Space Telescope observations of M 4—the closest globular cluster—that probe the lower Main Sequence down to the hydrogen‐burning limit. The unveiled stellar sequence reaches much fainter luminosities than previously possible, revealing a few extremely red objects that are consistent with brown dwarfs as cool as Teff∼1000K$
L. R. Bedin +10 more
wiley +1 more source
Differential Astrometry of Sub-arcsecond Scale Binaries at the Palomar Testbed Interferometer [PDF]
, 2003 We have used the Palomar Testbed Interferometer to perform very high precision differential astrometry on the 0.25 arcsecond separation binary star HD 171779.
Lane, B. F., Muterspaugh, M. W.
core +1 more source
Earth and Space Science, Volume 12, Issue 10, October 2025.Abstract High‐precision Earth Rotation Parameter (ERP) products often experience delays that range from several days to weeks. The use of precise forecasting models can effectively compensate for the impact of such delays. Based on a systematic analysis of the forecasting capabilities of the traditional harmonic least squares fitting and autoregressive
Chen Ren +4 more
wiley +1 more source