Results 101 to 110 of about 111,221 (213)

Periodic Gamma-Ray Modulation of the Blazar PG 1553+113 Confirmed by Fermi-LAT and Multiwavelength Observations

open access: yesThe Astrophysical Journal
A 2.1 yr periodic oscillation of the gamma-ray flux from the blazar PG 1553+113 has previously been tentatively identified in ∼7 yr of data from the Fermi Large Area Telescope.
S. Abdollahi   +100 more
doaj   +1 more source

The 3B/X3 solar flare of 27 February 1992 [PDF]

open access: yesGeofísica Internacional, 2000
Active region NOAA 7070 was related to a 3B/X3 solar flare that occurred on February 27, 1992. The soft X-ray flare observations were obtained by the SXT (Soft X-ray Telescope) on board the Yohkoh satellite, and those in Hα from the Udaipur Observatory ...
P. Démoulin   +3 more
doaj  

The high-redshift Universe with the International X-ray Observatory [PDF]

open access: yesarXiv, 2010
We discuss some of the main open issues related to the light-up and evolution of the first accreting sources powering high redshift luminous quasars. We discuss the perspectives of future deep X-ray surveys with the International X-ray Observatory and possible synergies with the Wide Field X-ray Telescope.
arxiv  

Triggering the Untriggered: The First Einstein Probe-detected Gamma-Ray Burst 240219A and Its Implications

open access: yesThe Astrophysical Journal Letters
The Einstein Probe (EP) achieved its first detection and localization of a bright X-ray flare, EP240219a, on 2024 February 19, during its commissioning phase.
Yi-Han Iris Yin   +51 more
doaj   +1 more source

Alternative Approaches for Estimating Highest‐Density Regions

open access: yesInternational Statistical Review, EarlyView.
Summary Among the variety of statistical intervals, highest‐density regions (HDRs) stand out for their ability to effectively summarise a distribution or sample, unveiling its distinctive and salient features. An HDR represents the minimum size set that satisfies a certain probability coverage, and current methods for their computation require ...
Nina Deliu, Brunero Liseo
wiley   +1 more source

Monitoring Variable X-ray Sources in Nearby Galaxies [PDF]

open access: yesarXiv, 2011
In the last decade, it has been possible to monitor variable X-ray sources in nearby galaxies. In particular, since the launch of Chandra, M31 has been regularly observed. It is perhaps the only nearby galaxy which is observed by an X-ray telescope regularly throughout operation.
arxiv  

Markarian Multiwavelength Data Center (MMDC): A Tool for Retrieving and Modeling Multitemporal, Multiwavelength, and Multimessenger Data from Blazar Observations

open access: yesThe Astronomical Journal
The Markarian Multiwavelength Data Center ( MMDC ) is a web-based tool designed for accessing and retrieving multiwavelength and multimessenger data from blazar observations.
N. Sahakyan   +9 more
doaj   +1 more source

ESA INTEGRAL and Cataclysmic Variables

open access: yesOdessa Astronomical Publications, 2017
The satellite INTEGRAL is ESA project operating since January 2003. It is dedicated to high energy astronomy. INTEGRAL is able to detect and perform astrometry, photometry and spectroscopy of sources from X-ray to gamma-ray regime (nominal range of ...
Jan Strobl   +4 more
doaj   +1 more source

<title>Energetic x-ray imaging survey telescope (EXIST)</title> [PDF]

open access: green, 1995
J. E. Grindlay   +8 more
openalex   +1 more source

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