Astronomy Picture of the Day . Centaurus A: X-Rays from an Active Galaxy . ... The diffuse high-energy glow represents gas throughout the galaxy heated to temperatures of millions of degrees C. At 11 million light-years distant in the constellation Centaurus , Centaurus A (NGC 5128) is the closest active galaxy . ... Publications with keywords: Centaurus A - NGC 5128 - X-ray - active galaxy . Publications with words: Centaurus A - NGC 5128 - X-ray - active galaxy . ... The Arms of NGC 4258 . ...

... The BM effect causes low-luminosity blazars (particularly BL Lacs) to be missed in surveys because the apparent luminosity of the non-thermal nuclear source does not exceed that of the host galaxy by a large factor. ... Browne (1995). ... In addition to these objects, a large fraction of the newly-identified BL Lacs in our sample (10 of 22; see Table 5) have been so classified only by virtue of our usage of the expanded March? et al. (1996) definition of the BL Lac class. ... 1996). ...

... 2001 August 16 . Centaurus A: X-Rays from an Active Galaxy . ... CXO , NASA . ... Astronomers were not disappointed, as Centaurus A's appearance in x-rays makes its classification as an active galaxy easy to appreciate. ... Blasting toward the upper left corner of the picture, the jet seems to arise from the galaxy's bright central x-ray source -- suspected of harboring a black hole with a million or so times the mass of the Sun. ... About APOD | ... NASA Technical Rep.: ...

... Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 8 A8 --- Field Field designation (1) 10- 11 I2 h RA1h First boundary field right ascension ( 1950.0 ) 13- 14 I2 min RA1m First boundary field right ascension ( 1950.0 ) 16- 20 F5.2 s RA1s First boundary field right ascension ( 1950.0 ) 22- 23 I2 h RA2h Second boundary ...

... Galaxy Evolution home . ... Micro quasars Publications . ... In the last few years a very similar phenomenon has been observed in some X-ray binaries, binary stellar systems with one gravitationally-compact object (black hole or neutron star) and an "normal" star part of whos atmosphere is captured by the compact object. ... The compact objects (a few solar masses) are much smaller than those inferred in AGN (10 9 solar masses), and the sizes much smaller, so the analogy may not be complete. ...

... The search for distant objects which can be both galaxies and quasars is one of the most important problems of observational astrphysics, because it allows one to determine cosmological parameters connected with the time of appearence and evolution of stellar systems, large scale structure of the Universe. ... Radio galaxies are important objects to be studied because they are sources of infrared-optical-ultraviolet continuum, emission lines and continual radio emission. ...

As a service to the astronomical community, we are recalibrating all archival Hubble Space Telescope Faint Object Spectrograph UV and optical spectrophotometry of active galaxies and quasars in order to extract uniformly calibrated spectrophotometric data for further detailed scientific investigations. ... NGC 4151 CLOUD F . NGC 5548 . ... NGC 4395 . ... NGC 4486 . ... NGC 4486 JET KNOT-A . ... NGC 4486 CLOUD-A . ... NGC 3031 . ... NGC 1068 . ... NGC 1068 CLOUD A . ... 1413+117A . ... NGC 4151 . ...

... 2015: . Explanation of the Origin of Ultraluminous X-Ray Sources . Using optical spectroscopy, we revealed the origin of unusual objects: ultraluminous X-ray sources in other galaxies, which radiate in the X-ray range thousands times stronger than the black holes in our Galaxy. ... Detection of Radio Transients and Variable Radio Sources using the Archive Data of the Cold Surveys . ... O.Zhelenkova ), E.Majorova, A.Temirova . ... E.Majorova, O.Zhelenkova. ... Archive . ...

... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... Risks Comparable to NEOs . ... The Increasing Rate of Discovery of Asteroids . ... Comet and Asteroid Collision Probabilities . ... Extreme albedo comets and the impact hazard (PDF Format) . ... Asteroid Impact Animations . ... Workshop on Scientific Requirements for Mitigation of Hazardous Comets and Asteroids - 2002 . ... The Spaceguard Survey Report, 1992 (PDF) . Tsunami from Asteroid/Comet Impacts . ...

... In one situation, we can use light from quasars to probe the material between us and them because that light may pass through one or more galaxies or gas clouds on its way to us. The gas inside the galaxies or the intergalactic clouds acts then as a filter, absorbing selected wavelengths from the quasar light. ... Light from a quasar must pass through clouds of gas and even faint galaxies -- each leaving its imprint on the light -- before we receive it here on Earth. ... Gravitational lensing . ...

... A universal physical relation for quasars . ... Harvey Tananbaum and his collaborators have first observed a relation between the soft X-ray and the optical/ultraviolet emission in AGN in 1979. Such relation is nonlinear, and it is usually parameterized as dependence between the logarithm of the monochromatic luminosities at 2500 †Е ( L 2500†Е ) and 2 keV ( L 2keV ) . ... Yet, the dispersion along the L 2500†Е тАУ L 2keV relationship is found to be rather high, typically ~0.35тАУ0.4 in log units. ...

USING THE CORRELATION BETWEEN ISGRI SURVEY RESULTS AND OTHER CATALOGUES TO AID SOURCE IDENTIFICATION John B. Stephen, A. Malizia and L. Bassani IASF-INAF, Via P. Gobetti 101, 40129 Bologna, ITALY, E-mail: stephen@iasfbo.inaf.it ABSTRACT In order to help in the identification of INTEGRAL/ISGRI sources, we have developed a software package which allows a rapid and detailed cross-correlation to be performed between various source catalogues. ... We show below some preliminary results from this analysis. ...

... Online Resources . ... Australia Telescope 20GHz Survey . ... Radio Sources in the 2dF Galaxy Redshift Survey. ... We present the first results from a study of the radio continuum properties of galaxies in the 2dF Galaxy Redshift Survey, based on thirty 2dF fields covering a total area of about 100deg 2 . ... mag. are detected as radio continuum sources in the NRAO VLA Sky Survey (NVSS). ... radio continuum: galaxies, galaxies: distances and redshifts, galaxies: active, galaxies: starburst . ...

... I note that "Z" plays an important role in what the ALFA surveys will look for: . ... low Z . nearby low mass . ... Arecibo . ... ADBS (Arecibo Dual Beam Survey): Rosenberg & Schneider 2002. ... A few sources with unobvious optical counterparts. ... Coverage wins for volume, but if you do a shallow survey you are sampling only the nearby volume at low masses. ... So need artificial test sources to find completeness. ... Total volume within survey in which source could have been detected. ...

. Active galaxies called blazars constitute the single largest source class in the second Fermi LAT catalog, but nearly a third of the sources are unassociated with objects at any other wavelength. Their natures are unknown. Credit: NASA's Goddard Space Flight Center

... The hard gamma radiation from AGN is produced most probably in the relativistic jets observed in the considerable part of these objects. In the center of AGN (and may be of all other galaxies) there is a supermassive black hole surrounded by the accretion disk, which is the source of the energy in these objects. ... The problem of particle acceleration in the AGN jets is very important: the time of the electron energy losses in the jets is usually much less than their life time. ... next page . ...

... Courtesy of NASA/ESA Observation data (J2000 epoch) Constellation Right ascension Declination Redshift Distance Type Serpens Caput 15h 17m 14.4s[] +21° 35 08[] 12,740±50 km/s[][1] 600±30 Mly (183±8 Mpc)[1] SA0(r) [citation needed ] [a] Apparent dimensions (V) 0.28 в 0.28[] Apparent magnitude (V) 16.0[] Notable features Ring galaxy Other designations PGC 54559,[] PRC D-51[] See also: Galaxy, List of galaxies Hoag's Object is a non-typical galaxy of the type known as a ring galaxy. ...

... We suggest simple method of the selection of distant galaxies based on their radio properties. ... RC0015+0503a , RC0015+0503b , RC0015+0501 , RC0034+0513 , RC0038+0449 , RC0042+0504 . ... RC0105+0501 , RC0110+0500 , RC0117+0503 , RC0126+0502 , RC0133+0459 , RC0135+0450 , RC0137+0539 , RC0143+0505 , RC0152+0453 , RC0154+0459 , RC0159+0448 . ... RC0209+0501b , RC0213+0516 , RC0226+0512 , RC0250+0512 . ... RC0302+0456 , RC0308+0454 , RC0311+0507 , RC0318+0456 , RC0355+0449 . ...

... We report initial results of cross-identification of extragalactic objects from the NASA/IPAC database and Guide Star Catalog (GSC). ... The NASA/IPAC Extragalactic Database (NED) contains positions, extensive data, and 1,023,000 cross-identifications for over 592,000 extragalactic objects (galaxies, quasars, and radio sources). ... Catalogs and lists are being integrated into NED on a continuing basis, following a detailed cross-identification process. ... Final cross-identification results: . ...

... The distributions of orbits eccenttricities and of angular momenta for the halo stars and the old disk population are considered. The distributions have gaps separating the halo from the disk and dividing the halo population into three groups. ... Рассмотрены распределения звезд гало и старого населения диска по величине эксцентриситета орбит и угового момента. Распределения имеют провалы, отделяющие гало от диска и делящие населения гало на три группы. ...