Results 41 to 50 of about 46,290 (218)

A Comparative Study of VTEC Estimates Derived From S/X VLBI and VGOS Observations

Space Weather, Volume 23, Issue 12, December 2025.
Abstract The ionosphere, which strongly varies in time and space, is one of the largest error sources for microwave measurements, if not accounted for accurately. Especially for single‐frequency observations, precise ionospheric models are needed to correct for the ionospheric delays. This study explores the utility of Very Long Baseline Interferometry
Arno Rüegg, Grzegorz Kłopotek, Benedikt Soja   +2 more
wiley   +1 more source

HST Astrometry of M4 and the Galactic Constant V_0/R_0

, 2003
From multi-epoch WFPC2/HST observations we present astrometric measurements of stars in the Galactic globular cluster M4 (NGC 6121) and in the foreground/background. The presence of an extragalactic point source allows us to determine the absolute proper
Bolzonella M., Cristiani S., Giampaolo Piotto, Ivan R. King, Jay Anderson, Kerr F. J., Luigi R. Bedin   +6 more
core   +1 more source

HEAD IN THE STARS, FEET ON THE GROUND: Scale and Astronomy Initiatives in Southern Africa

Cultural Anthropology, Volume 40, Issue 4, Page 571-596, November 2025.
ABSTRACT This article explores the evolution of radio astronomy in South Africa and Madagascar, focusing on how “scale” functions as both a way of understanding the world and marking differences in existence. In outer space research, the ground is crucial but often overlooked.
HANNA NIEBER, DAVIDE CHINIGÒ
wiley   +1 more source

Measurement of the Cosmic Optical Background using the Long Range Reconnaissance Imager on New Horizons

, 2017
The cosmic optical background is an important observable that constrains energy production in stars and more exotic physical processes in the universe, and provides a crucial cosmological benchmark against which to judge theories of structure formation ...
Cooray, Asantha, Immel, Poppy, Lisse, Carey M., Nguyen, Chi, Poppe, Andrew R., Zemcov, Michael   +5 more
core   +1 more source

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

Improved GALEX UV Photometry for 700,000 SDSS Galaxies

The Astrophysical Journal Supplement Series, 2023
The Galaxy Evolution Explorer (GALEX) satellite performed the first and only large-area UV survey, which in tandem with the Sloan Digital Sky Survey (SDSS) has facilitated modeling of the spectral energy distributions of low-redshift galaxies and the ...
Chandler Osborne, Samir Salim, Médéric Boquien, Mark Dickinson, Stéphane Arnouts   +4 more
doaj   +1 more source

Apart Cen A are UHECR mostly heavy radioactive and galactic nuclei?

, 2012
Earliest AUGER UHECR anisotropy correlated with AGN within a GZK Universe almost fade away. Recent UHECR mass compositions did show a negligible nucleon composition and an UHECR nuclei (light or heavy) signature.
Fargion, Daniele
core   +1 more source

On the Age Distribution of Classical Cepheids in the Galaxy

Astronomische Nachrichten, Volume 346, Issue 5, June 2025.
ABSTRACT We revisit the problem of the positive correlation between age and Galactocentric distance seen in Galactic Classical Cepheids, which at first sight may seem counter‐intuitive in the context of inside‐out galaxy formation. To explain it, we use the Besançon Galaxy Model and a simulation of star particles in the Galactic disc coupled with ...
Friedrich Anders, Chloé Padois, Marc Vilanova Sar, Marcin Semczuk, Marc del Alcázar‐Julià, Francesca Figueras   +5 more
wiley   +1 more source

Deconvolving X-Ray Galaxy Cluster Spectra Using a Recurrent Inference Machine

The Astronomical Journal
Recent advances in machine learning algorithms have unlocked new insights in observational astronomy by allowing astronomers to probe new frontiers. In this article, we present a methodology to disentangle the intrinsic X-ray spectrum of galaxy clusters ...
Carter Lee Rhea, Julie Hlavacek-Larrondo, Alexandre Adam, Ralph Kraft, Ákos Bogdán, Laurence Perreault-Levasseur, Marine Prunier   +6 more
doaj   +1 more source

Galactic and Extragalactic Samples of Supernova Remnants: How They Are Identified and What They Tell Us

, 2017
Supernova remnants (SNRs) arise from the interaction between the ejecta of a supernova (SN) explosion and the surrounding circumstellar and interstellar medium. Some SNRs, mostly nearby SNRs, can be studied in great detail. However, to understand SNRs as
A Rest, A Rest, B Aschenbach, BE Westerlund, BF Williams, BM Gaensler, BW Grefenstette, C Badenes, C Badenes, CK Kumar, CK Lacey, D Milisavljevic, D Milisavljevic, D Pinheiro Gonçalves, D Urošević, DA Green, DA Green, DH Clark, DM Fenech, DM Matonick, DS Mathewson, DS Mathewson, DS Mathewson, DS Mathewson, E Oliva, E Oliva, E Sonbas, E Sonbaş, EA Magnier, EG Berezhko, EJ Crawford, EM Berkhuijsen, F Haberl, F Vogt, FD Seward, FD Seward, Fermi LAT Collaboration et al, G Dubner, GL Case, H Mouri, H Stiele, I Leonidaki, I Leonidaki, IJ Danziger, IR Tuohy, IS Shklovskii, JA Morse, JC Raymond, JC Raymond, JE Drew, JE Drew, JH Lee, JH Lee, JJ Lee, JL Payne, JL Payne, JL Payne, JM Saken, JN Clarke, JP Hughes, JP Hughes, JR Dickel, JU Busser, JY Seok, K Koyama, KA Arnaud, KD Kuntz, KS Long, KS Long, KS Long, KS Long, KS Long, KS Long, L Chomiuk, L Chomiuk, L Sabin, M Sasaki, MA Dopita, MA Dopita, MA Greenhouse, MD Filipović, MG Allen, MG Lee, MM Vučetić, MZ Pavlovic, MZ Pavlović, NA Franchetti, O Kargaltsev, O Krause, P Kahabka, P Maggi, P Massey, P Predehl, PF Winkler, PF Winkler, PP Kronberg, R Braun, R Minkowski, RA Chevalier, RA Chevalier, RA Fesen, RA Fesen, RA Fesen, RG Arendt, RP Kirshner, RP Kirshner, S Dodorico, S Dodorico, S D’Odorico, S Park, SC Russell, SL Finkelstein, SM Gordon, SM Gordon, SP Reynolds, SR Kulkarni, T DeLaney, T Güver, T Morel, TA Thompson, TG Pannuti, TG Pannuti, TJ Galvin, TL Cline, VV Dwarkadas, W Li, W Pietsch, WC Millar, WJ Robbins, WM Goss, WP Blair, WP Blair, WP Blair, WP Blair, WP Blair, WP Blair, WP Blair, WP Blair, WT Reach, X Barcons, YH Chu, YH Chu, ZG Jennings, ZG Jennings, ZP Huang   +144 more
core   +1 more source