Results 141 to 150 of about 11,793 (207)

Time-lapse Very Long Baseline Interferometry Imaging of the Close Active Binary HR 1099

The Astrophysical Journal
We report multiepoch astrometric very long baseline interferometry observations of the chromospherically active binary HR 1099 (V711 Tau, HD 22468) at six epochs over 63 days using the Very Long Baseline Array at 22.2 GHz.
Walter W. Golay, Robert L. Mutel, Evan E. Abbuhl   +2 more
doaj   +1 more source

Evidence of Enhanced Ionization in Protostellar Envelopes

The Astronomical Journal
Ionization is a major driver of both physical and chemical evolution in protostellar systems. Recent observations reveal substantial chemical processing in protoplanetary disks by the time the surrounding envelope has cleared.
K. R. Schwarz, S. Maret, M. R. A. Wells, C. Gieser, A. Belloche, P. Andre, C. Codella   +6 more
doaj   +1 more source

A repeating fast radio burst associated with a persistent radio source. [PDF]

Nature, 2022
Niu CH, Aggarwal K, Li D, Zhang X, Chatterjee S, Tsai CW, Yu W, Law CJ, Burke-Spolaor S, Cordes JM, Zhang YK, Ocker SK, Yao JM, Wang P, Feng Y, Niino Y, Bochenek C, Cruces M, Connor L, Jiang JA, Dai S, Luo R, Li GD, Miao CC, Niu JR, Anna-Thomas R, Sydnor J, Stern D, Wang WY, Yuan M, Yue YL, Zhou DJ, Yan Z, Zhu WW, Zhang B.   +34 more
europepmc   +1 more source

Time, geodesy, and astrometry: Results from radio interferometry [PDF]

The results from a total of a dozen transcontinental and intercontinental VLBI experiments are discussed. Particular emphasis is placed on: (1) the inferred behavior of the frequency standards, usually hydrogen masers, on time scales from 10 to 100,000 ...
Clark, T. A., Shapiro, I. I.
core   +1 more source

Extragalactic radio and optic fundamental astrometry

A presentation at the IAU meeting in 2024.
openaire   +3 more sources

A Tri-Band Cooled Receiver for Geodetic VLBI. [PDF]

Sensors (Basel), 2021
López-Pérez JA, Tercero-Martínez F, Serna-Puente JM, Vaquero-Jiménez B, Patino-Esteban M, García-Carreño P, González-García J, García-Pérez Ó, Beltrán-Martínez FJ, Albo-Castaño C, Gallego-Puyol JD, López-Fernández I, Díez-González C, Malo-Gómez I, Barbas-Calvo L, de Vicente-Abad P, López-Fernández JA.   +16 more
europepmc   +1 more source

Inter-Comparison of UT1-UTC from 24-Hour, Intensives, and VGOS Sessions during CONT17. [PDF]

Sensors (Basel), 2022
Raut S, Heinkelmann R, Modiri S, Belda S, Balidakis K, Schuh H.   +5 more
europepmc   +1 more source

VLBI Astrometry of the Hipparcos Link Radio Stars [PDF]

International Astronomical Union Colloquium, 1991
J-F. Lestrade, R.A. Preston, D.C. Gabuzda, R.B. Phillips   +3 more
openaire   +1 more source

Challenges and opportunities for time-delay cosmography with multi-messenger gravitational lensing. [PDF]

Philos Trans A Math Phys Eng Sci
Birrer S, Smith GP, Shajib AJ, Ryczanowski D, Arendse N.   +4 more
europepmc   +1 more source

Extreme Artificial Airglow Induced by HF Pumping Sporadic E Layer at the SURA Facility. [PDF]

Sensors (Basel)
Beletsky A, Tkachev I, Grach S, Shindin A, Nasyrov I, Kogogin D, Emeljanov V, Legostaeva Y, Tareeva E, Moiseev S, Vasilyev R.   +10 more
europepmc   +1 more source