Results 111 to 120 of about 36,409 (218)

VLBA Astrometry of the Galactic Double Neutron Stars PSR J0509+3801 and PSR J1930–1852: A Preliminary Transverse Velocity Distribution of Double Neutron Stars and its Implications

open access: yesThe Astrophysical Journal
The mergers of double neutron star (DNS) systems are believed to drive the majority of short γ -ray bursts (SGRBs), while also serving as production sites of heavy r -process elements.
Hao Ding   +5 more
doaj   +1 more source

An Angular Diameter Measurement of β UMa via Stellar Intensity Interferometry with the VERITAS Observatory

open access: yesThe Astrophysical Journal
We use the Very Energetic Radiation Imaging telescope Array System (VERITAS) imaging air Cherenkov telescope array to obtain the first measured angular diameter of β UMa at visual wavelengths using stellar intensity interferometry (SII) and independently
A. Acharyya   +47 more
doaj   +1 more source

First Sagittarius A* Event Horizon Telescope Results. VII. Polarization of the Ring

open access: yesThe Astrophysical Journal Letters
The Event Horizon Telescope observed the horizon-scale synchrotron emission region around the Galactic center supermassive black hole, Sagittarius A* (Sgr A*), in 2017. These observations revealed a bright, thick ring morphology with a diameter of 51.8 ±
The Event Horizon Telescope Collaboration   +285 more
doaj   +1 more source

A Geodetic and Astrometric VLBI Experiment at 22/43/88/132 GHz

open access: yesThe Astronomical Journal
Extending geodetic and astrometric Very Long Baseline Interferometry (VLBI) observations from traditional centimeter wavebands to millimeter wavebands offers numerous scientific potentials and benefits. However, it was considered quite challenging due to
Shuangjing Xu   +16 more
doaj   +1 more source

Very long baseline interferometry using a radio telescope in Earth orbit [PDF]

open access: yes
Successful Very Long Baseline Interferometry (VLBI) observations at 2.3 GHz were made using an antenna aboard an Earth-orbiting spacecraft as one of the receiving telescopes.
Edwards, C. D.   +2 more
core   +1 more source

A Repeating Fast Radio Burst Source in the Outskirts of a Quiescent Galaxy

open access: yesThe Astrophysical Journal Letters
We report the discovery of the repeating fast radio burst (FRB) source FRB 20240209A using the Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB telescope.
Vishwangi Shah   +48 more
doaj   +1 more source

Bayesian Constraints on the Ring Ellipticity of M87* 2017 Using Themis

open access: yesThe Astrophysical Journal
Measuring the properties of black hole images has the potential to constrain deviations from general relativity on horizon scales. Of particular interest is the ellipticity of the ring that is sensitive to the underlying spacetime.
Paul Tiede, Avery E. Broderick
doaj   +1 more source

Time frequency requirements for radio interferometric earth physics [PDF]

open access: yes
Two systems of VLBI (Very Long Baseline Interferometry) are now applicable to earth physics: an intercontinental baseline system using antennas of the NASA Deep Space Network, now observing at one-month intervals to determine UTI for spacecraft ...
Fliegel, H. F., Thomas, J. B.
core   +1 more source

Astronomy using basic Mark 2 very long baseline interferometry [PDF]

open access: yes
Two experiments were performed in April and September 1976 to determine precise positions of radio sources using conventional Mark 2 VLBI techniques. Four stations in the continental United States observed at a wavelength of 18 cm.
Backer, D. C.   +3 more
core   +1 more source

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