Search results for "marka"
showing 10 items of 22 documents
Long-term monitoring of mrk 501 for its very high energy γ emission and a flare in 2011 october
2012
"As one of the brightest active blazars in both X-ray and very high energy γ -ray bands, Mrk 501, is very useful for" "physics associated with jets from active galactic nuclei. The ARGO-YBJ experiment has monitored Mrk 501 for γ - rays above 0.3 TeV since 2007 November. The largest flare since 2005 was observed from 2011 October and lasted until about 2012 April. In this paper, a detailed analysis of this event is reported. During the brightest γ -ray flaring episodes from 2011 October 17 to November 22, an excess of the event rate over 6σ is detected by ARGO-YBJ in the direction of Mrk 501, corresponding to an increase of the γ -ray flux above 1 TeV by a factor of 6.6 ± 2.2 from its steady…
Discovery of off-axis jet structure of TeV blazar Mrk 501 with mm-VLBI
2016
Context. High-resolution millimeter wave very-long-baseline interferometry (mm-VLBI) is an ideal tool for probing the structure at the base of extragalactic jets in detail. The TeV blazar Mrk 501 is one of the best targets among BL Lac objects for studying the nature of off-axis jet structures because it shows different jet position angles at different scales. Aims. The aim of this study is to investigate the properties of the off-axis jet structure through high-resolution mm-VLBI images at the jet base and physical parameters such as kinematics, flux densities, and spectral indices. Methods. We performed Very Long Baseline Array (VLBA) observations over six epochs from 2012 February to 201…
Gamma-Ray Flares from Mrk421 in 2008 observed with the ARGO-YBJ detector
2010
In 2008 the blazar Markarian 421 entered a very active phase and was one of the brightest sources in the sky at TeV energies, showing frequent flaring episodes. Using the data of ARGO-YBJ, a full coverage air shower detector located at Yangbajing (4300 m a.s.l., Tibet, China), we monitored the source at gamma ray energies E > 0.3 TeV during the whole year. The observed flux was variable, with the strongest flares in March and June, in correlation with X-ray enhanced activity. While during specific episodes the TeV flux could be several times larger than the Crab Nebula one, the average emission from day 41 to 180 was almost twice the Crab level, with an integral flux of (3.6 +-0.6) 10^-1…
Zvaigžņotā Debess: 2010/11, Ziema (210)
2010
Contents: “ZVAIGŅOTĀ DEBESS” FORTY YEARS AGO: Bursting Stars. J. Francman (abridged). Geodesists Help Renew the Spire of St. Peter’s Church. J. Klētnieks (abridged). DEVELOPMENTS in SCIENCE: The Solar Neutrino Problem. O. Smirnova. NEWS: At Last the Planet at the Star β Pictoris Is Imaged. A. Alksnis, Z. Alksne. SPACE RESEARCH and EXPLORATION: The Trail of an Asteroid Reveals a Recent Collision. A. Alksnis. INTERNATIONAL YEAR of ASTRONOMY 2009: International Year of Astronomy 2009 in Philately. The Rest of the World except Series EUROPA (concluded). J. Limansky. ACADEMIC STAFF of the UNIVERSITY of LATVIA: Assistant Professor in Physics Ojārs Šmits (24.04.1930.-14.03.1993.) of the Latvian Un…
Zvaigžņotā Debess: 2011, Vasara (212)
2011
Contents: “ZVAIGŽŅOTĀ DEBESS” FORTY YEARS AGO: A.Balklavs. Extremely Distant New Objects of Metagalaxy (abridged) ; Newspaper „Literaturnaja Rossija” 9 April 1971. Astronautics: Yesterday, Today, Tomorrow (abridged) ; CONFERENCE “The VIEW from SPACE. FIRST MANNED SPACE FLIGHT – 50”: M.Gills. Conference on the Eve of Human Space Flight Anniversary ; J.Ekmanis, S.Negrejeva. Mstislav Keldysh and Golden Age of Soviet Science ; T.Millers. Contribution of Scientists of the Institute of Inorganic Chemistry to the Development of Space Technologies and Materials ; G.Vilka. Remembrance of Friedrich Zander in Rīga ; O.Plepis. My Contribution to the Development of Space Medicine ; J.Stradiņš. Latvia’s …
Zvaigžņotā Debess: 2012, Rudens (217)
2012
Saturs: P.Stučkas LVU ieguldījums astronomijas speciālistu sagatavošanā ; Starp "maldugunīm" un zvaigznēm ; A.Alksnis. Dawn kosmosa misija palīdz atklāt asteroīda Vesta noslēpumus ; D.Docenko. Komentārs: Par Higsa bozona atklāšanu ; I.P. Frīdriha Candera 125.dzimšanas dienai Krievijas Pasts izdevis marku ; P.Leckis. Mākoņu pārklātais pavadonis ; D.Kotlere, I.Šmelds. Kosmisko atlūzu novērojumi Ventspils Starptautiskajā radioastronomijas centrā ; Pirmo reizi “ZvD”: Dace Kotlere ; I.P. Divas dienas, godinot Jāni Ikaunieku (28.IV 1912.–27.IV 1969.) ; I.Pundure. Jāņa Ikaunieka devums Latvijas astronomijai ; N.Cimahoviča, Imants Vilks, R.Saveļjeva, T.Millers, A.Krastiņš. Atmiņas par Ikaunieku ; E…
Zvaigžņotā Debess: 2011, Pavasaris (211)
2011
Contents: “ZVAIGŽŅOTĀ DEBESS” FORTY YEARS AGO: A.Alksnis. XIV General Assembly of the International Astronomical Union (abridged) ; H.Strods. Jaunlaicene’s Watchmaker (abridged) ; I.Daube. At the Radioastrophysical Observatory of the Latvian Academy of Sciences (abridged). 50 YEARS SINCE GAGARIN’S SPACE FLIGHT: R.Misa. Dream about Cosmos ; A.Zalcmane. Konstantin Tsiolkovsky Astronautics Museum in Kaluga; E.Bērziņa. Outer Space in Pauls Stradins Museum of History of Medicine. NEWS: A.Alksnis. Different Faces of Whirpool Galaxy ; A.Alksnis. The Kleopatra’s Trio and other Minor Planets Groups. SPACE RESEARCH and EXPLORATION: V.Kalniņš. NASA Preparing Solar Probe Plus to Plunge into Sun's Atmos…
Zvaigžņotā Debess: 2011, Rudens (213)
2011
Contents: “ZVAIGŽŅOTĀ DEBESS” FORTY YEARS AGO: A.Spektors. New Radiotelescopes (abridged) ; N.Cimahoviča. Solar Researchers Gather in Samarkand (abridged) ; DEVELOPMENTS in SCIENCE: M.Krastiņš. Smallest Planet of Solar System: Riddle of Centuries (2nd part) ; NEWS: A.Alksnis. New Look at „Oddball” Star Cluster NGC 6791 ; CONFERENCE “The VIEW from SPACE. FIRST MANNED SPACE FLIGHT – 50”: U.Stirna. Creation of Space Technologies and Materials ; ACADEMIC STAFF of the UNIVERSITY of LATVIA: A.Salītis. Centenary of Latvian Astronomer Professor K.Šteins (1911-1983) ; LATVIAN SCIENTISTS: I.Vilks. Remembering Leonora Roze (1928-2010) ; For SCHOOL YOUTH: A.Bruņeniece, I.Dudareva. Human Adventure in Sp…
Zvaigžņotā Debess: 2010, Pavasaris (207)
2010
Contents: E.Cielēns. Have Events in Space Influenced Evolution of Life on the Earth? ; A.Balklavs. Do Pulsars Radiate also in X-Rays? ; Soviet Press materials. Satellite of Friendship In Orbit ; I.Kalviņš. Innovation in Latvia: an Illusion or Reality? ; I.Eglītis. Half Comet-Half Asteroid Discovered With Baldone Schmidt Telescope ; A.Alksnis. While Rosetta is on the Fly from Steins to Lutetia ; M.Gills. Astronomy beyond 2009 ; IAU1001 Press Release. The International Year of Astronomy 2009: The Largest Science Education and Public Outreach Event in History ; J.Limansky. The International Year of Astronomy 2009 in Philately. Series EUROPA ; A.Bruņeniece, I.Dudareva. Wonders of the Solar Syst…
Zvaigžņotā Debess: 2010, Rudens (209)
2010
Contents: G.Carevsky, I.Daube. Comet Bennett ; E.Fogels. Srinivasa Ramanujan ; M.Krastiņš. Smallest Planet of the Solar System: a Riddle of Centuries (1st part) ; A.Alksnis, Z.Alksne. Hot Jupiters and Their Retrograde Motion ; V.Karitāns. James Webb Space Telescope. What will it Be? ; K.Salmiņš. GFZ CHAMP Laser Tracking Award to SLR Station Riga ; J.Jansons. Vladimir Afanasjev, Officer of the Baikonur Cosmodrom in the 1970s (concluded) ; J.Limansky. International Year of Astronomy 2009 in Philately. Series EUROPA (2nd sequel) ; J.Dambītis. Centenary of Prominent Latvian Mathematician Ernests Fogels (1910-1985) ; J.Klētnieks. Sketches of History of Astronomy (concluded) ; M.Gills. Public Sun…