Results 21 to 30 of about 127,445,565 (301)
First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole [PDF]
, 2019 We present measurements of the properties of the central radio source in M87 using Event Horizon Telescope data obtained during the 2017 campaign. We develop and fit geometric crescent models (asymmetric rings with interior brightness depressions) using ...
Sasada, Mahito +1 more
core +2 more sources
ECOLOGICALLY SAFE OVER THE HORIZON METER WAVELENGTH RADAR FOR TERRITORIAL WATERS GUARD [PDF]
Radio Physics and Radio Astronomy, 2023 Subject and Purpose. Without regard to successes attained in the field of monitoring of territorial formations frontier areas and environment the problem of territorial waters guard and control of economic zone is as well as before actual for many states,
I. M. Mytsenko, A. N. Roenko
doaj +1 more source
First M87 Event Horizon Telescope Results. IX. Detection of Near-horizon Circular Polarization [PDF]
, 2023 Event Horizon Telescope (EHT) observations have revealed a bright ring of emission around the supermassive black hole at the center of the M87 galaxy. EHT images in linear polarization have further identified a coherent spiral pattern around the black ...
The Event Horizon Telescope Collaboration
core +1 more source
Remote Sensing, 2022 The evaporation duct (ED) is generated by the evaporation of seawater and can be an influential factor of electromagnetic (EM)-wave propagation. Rainfall also affects atmospheric factors and EM-wave propagation.
Fan Yang +5 more
doaj +1 more source
Broadband multi-wavelength properties of M87 during the 2017 Event Horizon Telescope campaign
, 2021 In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting ...
The Event Horizon Telescope Collaboration
core +1 more source
Impacts of Auroral Precipitation on HF Propagation: A Hypothetical Over‐the‐Horizon Radar Case Study
Space Weather, 2021 Over‐the‐horizon radar (OTHR) systems operating in the high‐frequency (HF) band (3–30 MHz) are unique in their ability to detect targets at extreme ranges, offering cost‐effective large‐area surveillance. Due to their reliance on the reflective nature of
Joshua J. Ruck, David R. Themens
doaj +1 more source
Two‐dimensional transmit arrays for polar over‐the‐horizon radar
IET Radar, Sonar & Navigation, 2021 Two‐dimensional (2‐D) transmit arrays offer many advantages over traditional over‐the‐horizon radar (OTHR) arrays, including the capability to steer and mitigate auroral clutter, a clutter type prevalent in polar operation, in all azimuth and elevation ...
Simon Henault, Ryan J. Riddolls
doaj +1 more source
Journal of Marine Science and Engineering, 2023 This paper represents observations on detection of Very High Frequency (VHF) anomalous propagation over the area of the Adriatic Sea. During the research campaign, a Software Defined Radio (SDR) Automatic Identification System (AIS) receiver was employed
Sanjin Valčić, David Brčić
doaj +1 more source
Index on Censorship, 1996 The oil must flow...and human rights and democracy are the price to be paid for security and stability In the Gulf. But for how long?
openaire +1 more source
Numerical Modeling of the Radio Wave Over-the-Horizon Propagation in the Troposphere
Atmosphere, 2022 Using atmospheric data, which include pressure, temperature, relative humidity and water vapor pressure, the actual refractive index of a specific segment of the atmosphere has been modeled.
Min Xu +6 more
doaj +1 more source