... 2011 May 23 . An Unexpected Flare from the Crab Nebula . ... As recently as one month ago, gamma-ray observations of the Crab Nebula by the Fermi Gamma Ray Space Telescope showed an unexpected increase in gamma-ray brightness, becoming about five times the nebula's usual gamma-ray brightness, and fading again in only a few days. ... The above image shows how the Crab Nebula normally appears in gamma rays, as compared to the Geminga pulsar, and how it then appeared during the recent brightening. ...

An Unexpected Flare from the Crab Nebula . ... Credit Copyright: NASA , DOE , Fermi LAT , R. Buehler ( SLAC , KIPAC ) Explanation: Why does the Crab Nebula flare? ... As recently as one month ago, gamma-ray observations of the Crab Nebula by the Fermi Gamma Ray Space Telescope showed an unexpected increase in gamma-ray brightness, becoming about five times the nebula's usual gamma-ray brightness, and fading again in only a few days. ... NASA Web Site Statements, Warnings, and Disclaimers . ...

... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... Armagh Observatory, 30 July 2015: The sky above a nearby "failed star" or brown dwarf lying in the summer constellation Lyra shimmers with a beautiful green and yellow aurora ten thousand times brighter than the northern lights. ... Even a few years ago, brown dwarfs were thought by most astronomers to be incapable of emitting any significant radio emission, so its first detection came as a great surprise. ...

... ATNF Home . About ATNF . ... About ATNF overview . ... Australia Telescope Steering Committee . ... Australia Telescope User Committee . ... Murchison Radio-astronomy Observatory . ... Parkes radio telescope . Australia Telescope Compact Array . Mopra radio telescope . ... Australia Telescope Online Archive (ATOA) . ... Parkes | ... Australia Telescope 20GHz Survey . ... Visiting Parkes radio telescope . ... Parkes radio telescope webcam . ... X-Ray Microlensing of Bright Quasars . ...

... A star party is a gathering of amateur astronomers who set up their telescopes and observe the dynamic night sky. ... Star parties are best scheduled during first quarter and waxing gibbous Moon. During full moon, the moon is so bright it obscures a view of other celestial objects and even the Moon is best viewed when NOT full. ... We will consult local weather forecasters and make a decision by 2:00p on the day of the star party. ... Copyright (c) Amateur Telescope Makers of Boston, Inc. ...

Proposal Identification No.: ... For these observations night-time is not needed. Begin ­ End Interval ­ Interval 1700 ­ 2200 ­ ­ ­ Days Needed at This Interval 14 Time Constraints (Must Be Justified in the Prop osal Text) In order of scheduling: 2 gridding sessions : 3.5h and 2.5h (ALFA) Starting at least a week later (L-wide or 327MHz, TBD by the gridding sessions ): 3 sessions of 3h each on successive days 1 session of 3h a week later 1 session of 3h two weeks later 11 monthly ...

... The Galactic low-mass X-ray binary GS 2023+338 was discovered during the burst on May 22, 1989 with the Japanise satellite Ginga (aka Galaxy). The flux reached 17 crabs (this unit of flux measurement is an bright X-ray source, Crab Nebula) at 10-35 keV. ... No other radio telescope worldwide carried out multi-frequency measurements. ... Upon 14 days the radio flux fell below the detection level at the RATAN-600 in relation to the decrease of the X-ray flux. ...

Next: Analysis in the Up: MIDAS utilities for Previous: Fourier analysis . For the detection of smooth signals, e.g. sinusoids, use either SCARGLE/TSA or AOV/TSA with bins. ... SCARGLE/TSA -- . Scargle sine model: This command computes Scargle's (1982) periodogram for unevenly spaced observations x . ... In this way, the command can be used to perform a CLEAN-like analysis manually by removing individual oscillations one by one in the time domain (see Roberts et al. ... AOV/TSA -- . ...

... Bringing news from across the Universe to children all around the world . ... Gamma-Ray Bursts are the brightest explosions in the Universe. ... We only see Gamma-Ray Bursts in very distant galaxies; galaxies so far away that it takes billions of years for their light to reach us. ... Astronomers think that Gamma-Ray Bursts are caused by the detonation of massive stars at the end of their lives. These blazing bursts of light are normally followed by a fainter afterglow. ...

Next: *timsort* Up: Timing Analysis Previous: Summary of tasks in . ... Events will be time ordered in the output file. xt> timsort xdata$snr psr ``c 503 513 24'' none A light curve is then generated and plotted so we can inspect the gross properties of the sample (the sequence of good-data intervals and gaps) and any source variability. xt> ltcurv psr none psr 500 xt> ltcplot psr_ltc Finding this sample satisfactory, we search for periodicity with a fast Fourier transform. ...

An Ancient Universe: How Astronomers Know the Vast Scale of Cosmic Time . THE ANCIENT UNIVERSE . c) The Age of Light from the Most Distant Galaxies: The "Time Machine" Effect . ... Thus we are actually seeing these galaxies not as they are today, but as they were billions of years ago. ... The Universe: An Overview | ... The Ancient Universe - The Age of the Expanding Universe - The Age of the Oldest Stars - The Age of Light From Distant Galaxies - The Age of the Chemical Elements | ...

... Measurements of recent changes in the expansion rate via supernovae , published by myself in 1998with the High-z Team ( Riess et al. 1998 ) and the Supernova Cosmology Project in 1999, first revealed that the expansion of the Universe is now accelerating.€а At the time , the High-z Team began (Schmidt et al. 1998) the Universe was expected to be decelerating under the gravitational braking applied by its own mass, so this finding was an enormous surprise ...

Please enter the lightcurve file name and period search parameters: . Lightcurve file: . ... Apply the Heliocentric correction and convert all dates to Terrestrial Time (TT)? ... Also, the Heliocentric correction cannot be applied to such lightcurves. ... This period search service is also available at the mirror sites: Mirror 1 , Mirror 2 , Mirror 3 , Mirror 4 . You may download the latest source code distribution and install the period search service at your own web server. ...

Photon Scattering: Basic Principle of Photon Scattering . Audio Narration is available . No Scattering: Photon Source and Detector . ... For optical photons, scattering goes as wavelength to the -4 power. In the case of blue photons compared to red photons, this means that blue photons are about 10 times more likely to get scattered than red photons. ... Watch the blue photons scatter away from the detector . ... Interstellar dust make stars appear redder than they really are . ...

... Exposure Time Calculator (ETC) . ... ESO - Public Surveys . ... the recommended values to use for DIT, . ... Detector on-chip integration (DIT): seconds. to your chosen value - a separate page gives recommended values to use for DIT - for modes 1 and 2 below you may wish to start with the maximum recommended values as these will minimize the effect of read noise (a total object exposure of Y secs with DIT=X secs will produce Y/X lots of read noise) and give you a lower limit on the time needed. ...

This sequence of three images, obtained by NASA's Cassini spacecraft over the course of about 10 minutes, shows the path of a newly found moonlet in a bright arc of Saturn's faint G ring. In each image, a small streak of light within the ring is visible. ... Scientists interpret the moving streak to be reflected light from a tiny moon that is likely a major source of material in the arc and the rest of the G ring. ... That arc, in turn, leaks material to form the entire ring. ...

This page is devoted to information on supernova 1999ee and 1999ex in IC 5179 Basic information on this SN, including the last reported brightness, on this Supernova can be found on the main supernova page. Information on the original web pages for many of these images can be found on the Supernova links web page. ... Use this 1999ee VSNet data query and this 1999ex VSNet data query to see what information has been reported so far. ... vsnet-alert 3714 ] SNe 1999ex and 1999ee in IC 5179 . ...

SAS home . ... You will find the period of a variable source and create a folded light curve of the object . ... We will run SAS and XRONOS . In pink is marked what you have to type at the command line or some useful scripts. ##########################script to extract a timing event file form ODF################################ . ... or ... setenv SAS_DIR /sas/Linux/RedHat9/sas6_1_0 . ... source $SAS_DIR/sas-setup.csh ... setenv SAS_ODF /SAS_Workshop/Timing/PSRB1509 . ... setenv SAS_CCF ccf.cif . ...

Next: Conclusion Up: No Title Previous: The Transmission Gratings . ... The potential of Chandra is illustrated in Figure which shows the official "first-light" image. ... Figure: The official CXO first light image - the supernova remnant CasA. Perhaps the neutron star - black hole connection and the utility of CXO are best illustrated by an early observation of the Crab Nebula and pulsar taken as part of the HETG calibration. ... Figure shows the zeroth-order image of the Crab Nebula. ...

... STScI-PRC96-03 and JPL-P-46536 HUBBLE FINDS SEARCHLIGHT BEAMS AND MULTIPLE ARCS AROUND A DYING STAR This image of the Egg Nebula, also known as CRL2688 and located roughly 3,000 light-years from us, was taken in red light with the Wide Field and Planetary Camera 2 (WFPC2) aboard NASA's Hubble Space Telescope. ... The central star in CRL2688 was a red giant a few hundred years ago. The nebula is really a large cloud of dust and gas ejected by the star, expanding at a speed of 20 km/s (115,000 mph). ...