... ClassX is a project aimed at creating an automated system to classify X-ray sources and is envisaged as a prototype of the Virtual Observatory. ... The most fundamental are: (a) classification methods and algorithms, (b) selection and definition of classes (object types), and (c) identification of source counterparts across multi-wavelength data. ... Using different sets of training parameters (attributes), we get different classifiers for the same list of class names (e.g., Figure 1). ...

... 2001 March 8 . Bright Venus . ... That's no star, that's planet Venus the second "rock" from the Sun . Blazing at -4.6 magnitude , Venus, after the Sun and Moon, is the third brightest celestial body in planet Earth's sky . ... This causes Venus to look brighter as it looms large in its crescent phases than when it is smaller and nearly full. Taken on January 28th, this dramatic picture finds a crescent Venus near its brightest to the right of a crescent Moon. ... About APOD | ...

... WFPC2 Home . ... Bright stars near the WFPC2 field of view can cause various artifacts to appear in science images. ... When writing Phase II proposals, observers will sometimes attempt to avoid bright stars by placing them in the un-imaged "L" shaped region adjacent to CCD PC1, or in the region just outside the nominal field of view. ... In both cases the optics can image this light back onto the CCD's. Bright stars must be placed at least 10 arcseconds outside the field to avoid artifacts. ...

In this gallery are many images of Low Surface Brightness Galaxies which have recently been discovered and analyzed. ... The central surface brightness of this galaxy is 24.28 . Malin 2 This galaxy is another huge disk galaxy with a scale length of 15 kpc and a redshift of 15000 km/a. The high surface brightness knot in one of its spiral arms actually has the same color, luminosity and H-alpha equivalent width as the entire Large Magellanic Cloud . ... Truly it is a Low Surface Brightness Galaxy. ...

XMM-Newton Science Analysis System . ... A different approach is done via the setting withctisrcpos =Y: all event energy corrections do not use the actual RAWY coordinate but the corresponding RAWY location of the source ( SRCPOS ) as determined by the task epframes (either automatically or via setting withsrccoords =Y). ... The task epchain may be used with the setting ccds =4 withctisrcpos =Y to process only the CCD 4 where usually the bright source is located that causes the Out-of-Time events. ...

... Albireo: A Bright and Beautiful Double . ... Such is the case of the bright double star Albireo . Seen at even slight magnification, Albireo unfolds from a bright single point into a beautiful double star of strikingly different colors. ... The brighter yellow star is itself a binary star system, but too close together to be resolved even with a telescope. ... Публикации с ключевыми словами: star system - двойные звезды . Публикации со словами: star system - двойные звезды . ...

... The two plots below illustrate two of the selection criteria: velocity width (limited by the channel width) and the HIPASS peak flux. Zoom-in on Figure 3a. The two plots below give some idea of the shape of the HI spectra. ... For Gaussian HI spectra the difference is slightly more, but for irrgeular galaxies, pairs and groups many different shapes are observed. ... Some trend towards detecting more narrow-width galaxies at higher velocities is visible. ...

Two major reasons: the number of stars isn't really seven (it's many more), and they all have different brightnesses, so that you see more or fewer of them depending on viewing conditions. The brightness of stars is measured on the magnitude scale, where the most prominent stars in the sky are around 1st magnitude, and the faintest you can see with your eye are about 6th. ... I think this makes it quite likely that the list will be truncated at Taygeta, giving six visible stars. ...

... Bad Astronomy . ... Bad Astronomy: The North Star, Polaris, is a very bright star. Good Astronomy: Polaris is a middling-bright star, easily missed. ... He said it was close to Polaris, the North Star, but he also said it was in the East. ... It's natural, I suppose, to think that such an important star should be bright, but really, that's a conceit, like thinking that the Earth is at the center of the Universe. If more people knew just why Polaris is the North Star, this Bad Idea would stop. ...

... SEARCH ASP SITE: Match ALL words Match ANY word . ... ASP Conference Series . ... Accidental Astrophysics: The Devil's In the Magnitudes, Part II . ... The star second to the Sun in brilliance is Sirius. ... Recall the magnitude system, passed down to us through a hundred generations of sky watchers, as a means of quantifying stellar brightness ("Accidental Astrophysics," May/June, p. 9). ... Yes, it is a magnitude difference, but that difference is due to the distance between us and the star. ...

Nova in M31 2000 3 . ... From Giovanni Sostero (Remanzacco Observatory): at the end we have found a good Nova candidate in the course of our monitoring program in M31. ... Remanzacco Observatory Light curve This is a preliminary lightcurve of Nova M31-3 from the images we collected and those provided by others. ... vsnet-alert 5346 ] [FWD] Suspected Nova in M 31 . ... vsnet-alert 5349 ] (fwd) M31 possible nova . ... vsnet-alert 5355 ] [FWD] New image of the possible Nova in M31 (GSo) . ...

... Tonight's Sky . ... The Magazine . ... Observing . ... Magazine . ... Gravitational wave search provides insights into galaxy evolution and mergers . ... The double star 54 Leonis, spiral galaxy NGC 3198, and emission nebula NGC 3199 . ... Astronomy for Kids . ... The different types of supernovae . ... Get instant access to subscriber content on Astronomy.com! ... Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter. ... Astronomy Magazine . ...

... Space flight . Crew training . ... The contemporary world opinion, while welcoming the efforts of different states aimed at realization of manned space flights, still considers these efforts insufficient, over-bureaucratized and too slow. ... The more up-to-date is the basic training program for a cosmonaut/astronaut or a manned space flight participant (hereinafter referred to as the student) that is being offered to your interested attention. ... Pre-flight space training (PFST). ...

... Now, think about a much bigger move: What do you think it would be like if the Earth moved to a different part of our Galaxy? Our Galaxy, the Milky Way, is shaped like a whirlpool: It has bands of stars that spiral around the centre, which astronomers call the Galaxy s arms . ... We live in the outer parts of the Milky Way, in one of its spiral arms. ... The small centre of the Milky Way is a much more crowded place, as this is where most of its stars are found. ...

... MOON OCCULTS PLEIADES, 23-24 FEBRUARY. ... known by different designations - don't worry if your PC programme or Atlas shows some of them with other Catalogue numbers STAR Mag Time V 624 Tau 8.2 E22.10 V 1187 Tau 8.3 E22.23 TYC 1803-188 E 8.1 E22.29 16 Tau 5.5 22.44 19 Tau 4.3 22.50 TYC 1799-306 E 8.5 E22.57 TYC 1803-104 E 8.9 E22.59 TYC 1799-184 E 7.2 E23.05 20 Tau 3.9 23.08 21 Tau 5.7 23.09 22 Tau 6.4 23.12 TYC 1804-2081 6.8 23.35 ... Clear Skies, Terry Moseley . ...

... Archives . ... Differential Emission Measure [Eqn] . ... Astro 301, class 1, and it took all of 20 minutes of talk about stellar magnitudes to put that notion to permanent rest. ... Now, it turns out that the human eye perceives brightness on a log scale, so magnitudes are numerically similar to log (brightness). ... frac{5}{2}\log_{10}\left(\frac{f_{object}}{f_{standard}}\right) \,,$$ . ... frac{5}{2}\log_{10}\left(\frac{L_{object}}{4 \pi d^2}\frac{1}{f_{standard}}\right) \,.$ ... Chandra Blog . ...

... 38 CONTENTS Karachentsev I.D., Kopylov A.I., Kopylova F. G. Distance moduli in M 101 group from brightest stars .. Tikhonov N.A., Karachentsev I.D. Maffei 2, a nearby galaxy shielded by the Milky Way.. ... Zhuravkov A.V. , Bartolini C., Guarnieri A., Piccioni A., Zampieri G. Optical behaviour of GRO J0422+32 in different brightness levels ............................................................................. telescope .. ... Cas OB5 .. ... Instrumental facilities of the 6 m telescope .. ...

... November 12, 1996 . Comet Hale-Bopp Passes M14 . ... Explanation : Comet Hale-Bopp continues its slow trek across the night sky, and can now be seen superposed near the bright globular cluster M14 . Will Comet Hale-Bopp become as bright in early 1997 as Comet Hyakutake did in early 1996? It is still too early to tell. ... Because of the size of coma , some speculate that the nucleus of Hale-Bopp is unusually large. ... Tomorrow's picture: Seven Jets from Comet Hale-Bopp . ... About APOD . ...

... 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. ...

... The ancient chronical said about the colour rings around the Sun and the Moon, about three suns in the sky, light columns, bright lightning, different "comets" rushing to the Earth, moving among the stars or round the Earth with the sky. All these occurrences may be divided into three categories: one that occur in the near or far space, processes going on in the Earth atmosphere under the influence of cosmic factors and at last the occurrences connected with the Earth atmosphere. ... Rainbow . ...