... 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 . ...

M1 image More About M1 Nice Color Picture . ... M16 image More About M16 HST image . ... M31 image More About M31 Nice Color Picture . ... M42 image ; M43 image More About M42/43 Nice Color CCD Picture . M51 image More About M51 Color Image of M51 M51 Supernova . M57 image More About M57 Nice Color CCD Picture Very Deep M57 Image . ... M81 image More About M81 M81 Supernova Ultraviolet Image of M81 More about Ultraviolet Imaging . M82 image More About M82 M82 False Color M82 True Color . ...

... 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 . ...

Next: Non emission-line objects Up: Results of follow-up spectroscopy Previous: Emission-line galaxies . In the course of our follow-up spectroscopy six QSOs were discovered with a strong emission line in the wavelength region between 5000 ? ... This strong line produces an easily visible emission peak in the digitized prism spectra even for very faint objects (B ) which is hard to distinguish from low-redshifted [O III ] features. ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. March 31, 1999 . PG 1115+080: A Gravitational Cloverleaf . ... Since light takes a different amount of time to traverse each path, each image shows the quasar as it appeared at a slightly different time in the past, creating time delays on the time scale of days. ... About APOD > . ...

... We construct a composite quasar spectrum from 149 HST FOS spectra of 80 quasars with mean redshift . ... The continuum longward of 1000? can be modeled as a power law with . ... The break in the power--law index is a feature expected in Comptonized accretion--disk spectra. ... The spectral features in the sub--Ly region of AGN spectra provide critical insights into the physical processes around the central engine, and they become accessible to IUE and HST at intermediate redshift. ...

... 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. ...

Subject, Problems and Objects of Theoretical Astrophysics. ... Stellar Photospheres, Their Features. ... Physics of Continuous Radiation Absorption in Stellar Photospheres. ... Continuous Radiation Absorption in Stellar Photospheres of Various Spectral Classes. Solar Type Photospheres. ... Characterisics of Absorption Lines. ... Interstellar Absorption Lines, Their Features. ... Physical and Dynamic Features of Interstellar Medium, Which Follows from Observations of Interstellar Absorption Lines. ...

Next: Analysis Tools for Nebular Emission Lines . ... Extracting spectra from a large number of NICMOS grism images requires a convenient interactive tool which allows a user to manipulate direct/grism image pairs. ... The direct image is used to locate objects of interest, to find the position of the appropriate spectra in the grism image, to determine the optimal extraction technique to use, and to calibrate the wavelength range of the extracted spectra. ... Figure 1: The NICMOSlook User Interface . ...

... This book explains how to use core and client-side JavaScript for version 1.3. JavaScript is Netscape's cross-platform, object-based scripting language for client and server applications. ... Core, Client-Side, and Server-Side JavaScript . ... Client-Side JavaScript . ... JavaScript and Java . ... Examples . ... Conditional Statements . ... Object Manipulation Statements . ... Defining Functions . ... Objects and Properties . ... Indexing Object Properties . ... Defining an Event Handler . ...

... A Distant Cluster of Galaxies . ... Oddly - most of them are spiral galaxies. This rich cluster of galaxies, named CL 0939+4713, is almost half way across the visible universe. ... Discovered in 1963, astronomers were astounded that such objects could be visible across billions of light-years, as this implies they must emit prodigious amounts of energy. ... Can you see through the spiral galaxy? ... Runaway Star . ... On the far side of our Galaxy, gas clouds explode away from a small black hole. ...

... Tonight's Sky . ... The Magazine . ... Observing . ... The double star 54 Leonis, spiral galaxy NGC 3198, and emission nebula NGC 3199 . ... Astronomy for Kids . ... Observing springtime deep-sky objects with a large telescope . ... Bright planets meet at dusk . ... Astronomy magazine subscribers can read the full article for free. ... Get instant access to subscriber content on Astronomy.com! ... Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter....

Next: Imaging Polarimetry with NICMOS Up: NICMOS Data Calibration and Previous: The Photometric Performance of . ... NICMOSlook and Calnic C . ... Extracting spectra from a large number of NICMOS grism images requires a convenient interactive tool which allows a user to manipulate direct/grism image pairs. ... NICMOSlook and Calnic-C are two programs that were designed to take advantage of the fact that the NICMOS grism mode typically consists of taking both a direct and a grism image. ...

... 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. ...

... Under certain conditions, like those in the nucleus of a QSO, all atoms can be made to emit light at particular wavelengths. ... If that source is approaching the observer, the wave is squashed up onto itself making the wavelength shorter. ... This is redshift. ... You can see how the section of the QSO spectrum which we observe changes with redshift. ... We then see how far we had to slide the observed spectrum along the scale to make it match and that is the objects redshift. ... The 2QZ team . ...

... ESO, the European Southern Observatory . ... ESO's Governing Bodies . ... Green ESO . ... Galaxies . Galaxy Clusters . ... This view includes infrared light images from the WFC3 instrument on the NASA/ESA Hubble Space Telescope as well as visible light views. It shows a close up look at part of the rich galaxy cluster Abell 1689. ... New observations with ALMA and ESOтАЩs VLT have revealed that€аA1689-zD1 is a dusty galaxy seen when the Universe was just 700 million years old. ... Abell 1689 . ...

We report the detection of the third H I 21-cm absorber in the sight-line towards the z=2.64 quasar MG J0414+0534 (4C +05.19). In addition to the absorption at the host redshift and in the z=0.96 gravitational lens, we find, through a decimetre-wave spectral scan towards this source, strong absorption at z=0.38. ... This suggests that, as for the lensing galaxy, this is not the primary location of the intervening material responsible for the very red colour of MG J0414+0534. | ...

Blackholes Forum Message . Forums: . ... Black Holes And RedShift . ... Perhaps black holes really are the reproductive means of the universe.Could the black hole of a Quasar red-shift the electromagnetic energy trying to escape it? ... Perhaps black holes treat electromagnetic energy the same way. ... No one really knows enough about Quasars and black holes to say for sure but ask yourself this: Why would all the Quasars in the universe be moving away from the Milky Way? ... www.astronomy.net . ...

... The variability of the spectrum of the optical component of the IR-source IRAS01005+7910 was discovered for the first time in the BTA spectra [1]. ... The spectral features include absorptions that form in near-photospheric layers, narrow envelope emissions, and emission-absorption profiles that form in photosphere-to-envelope transition layers (the wind). ... Discovery of spectral variation in the optical counterpart of IRAS01005+7910. ... Dashed line - envelope curve of all the SiII 5979 profiles ...

... We have measured this "redshift" for the pink black holes, and allowed for it in our calculations. ... We see this effect in the emission from gas around these pink black holes, but it is far too small an effect to account for the pinkness. Thus the swirling motions of gas around or into the black holes cannot produc the colour. ... At first we thought that these things were normal blue black holes hidden behind clouds of interstellar dust, that absorbed the blue light and made them appear pink. ...