... 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 . ...

... The ROSAT Bright Survey: II. Catalogue of all high-galactic latitude RASS sources with PSPC countrate CR > 0.2 s -1 . ... 1S We present a summary of an identification program of the more than 2000 X-ray sources detected during the ROSAT All-Sky Survey (Voges et al. 1999) at high galactic latitude, |b| > 30degr , with countrate above 0.2 s -1 . This program, termed the ROSAT Bright Survey RBS, is to more than 99.5% complete. ...

... The concerns here are similar to those for observing bright targets; saturation and blooming of the bright companion PSF must not impact the faint target. Also, one may need to consider subtracting the PSF of the bright object, and effects which limit the accuracy of that subtraction. If the bright companion will saturate and bloom, it will be necessary to rotate the CCD so that blooming along the CCD columns does not obliterate the faint target. ...

... 739C As one part of a program to detect complete samples of active extragalactic objects, the 3.36x10^-3 sr field centered on alpha=12h04min, delta=+11deg30' (1950.0) was mapped with the Very Large Array at 1411MHz. Sixty-seven maps cover this field so that no point is more than 15arcmin from the nearest map center. ... The rms map noise is 0.030 + 0.001 mJy, and the resulting source list is complete to a map peak flux density S_p = 0.2 mJy within 25 arcmin of the field center. ...

T he Siding Spring Survey (SSS) is a Near-Earth Object search program that utilises the 0.5-m Uppsala Schmidt Telescope at Siding Spring Observatory, N.S.W., Australia. ... The mission of the Siding Spring Survey is to contribute to the inventory of near-earth objects (NEOs), or more specifically, the potentially hazardous asteroids (PHAs) and comets (PHOs) that may pose a threat of impact and thus harm to civilization. ... Based on the CSS Mission page . ... Siding Spring Survey Main Page . ...

Next: Comments on Individual Sources Up: Sample Identification Previous: Sample Identification . In Figure 2, we show the spectra of the optical counterparts to 85 of 97 observed X-ray/radio sources. ... Positional information for all 85 sources for which we announce identifications herein are given in Table 3, including information from WGACAT, the PMN and Green Bank surveys, the NVSS and our ATCA survey. ... Of the 85 newly identified sources, 59 are FSRQs, and 22 are BL Lacs. ...

... Posts tagged ?incompleteness? ... Comment . ... The notions of missing data are overall different between two communities. ... Astronomers?I?m not sure how they think but my impression so far is that a missing value in one attribute/variable from a object/observation/informant, all other attributes related to that object become useless because that object is not considered in scientific data analysis or model evaluation process. ... 2 Comments . ... Entries RSS . ... Entries (RSS) and Comments (RSS)...

Up: Sky Surveys . ... The object catalogue and compressed pixel data are stored online and are accessible via the WWW. ... small area (up to 15arcmin) pixel images with attached object catalogue, . ... The primary data format is FITS for both images and binary tables of object catalogues, which enables porting of the data into established software packages. ... In this way, it is possible to browse the data by clicking on objects in the image display or the catalogue list to highlight them in both. ...

... 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. ...

... Hoags Object: A Strange Ring Galaxy . ... Credit: R. Lucas ( STScI / AURA ), Hubble Heritage Team , NASA Explanation: Is this one galaxy or two? ... How Hoag's Object formed remains unknown, although similar objects have now been identified and collectively labeled as a form of ring galaxy . ... Hoag's Object spans about 100,000 light years and lies about 600 million light years away toward the constellation of the Snake ( Serpens ). ... The Double Ring Galaxies of Arp 147 from Hubble . ...

... 2000 . ... Abstract: I present the distribution of the brightest galaxies in the southern sky as obtained from the H I Parkes All-Sky Survey (HIPASS). ... A histogram of the systemic velocities of the brightest HIPASS galaxies is shown in Fig. ... It peaks, as expected, in the interval 800 to 2000 km/s. No bright galaxies were found with systemic velocities of less than -350 or more than 5500 km/s. Figure 2: Histogram of the H I systemic velocities of the brightest galaxies obtained from HIPASS. ...

... The sample of the Local Volume galaxies (distance smaller than 10 Mpc) gives a unique opportunity to study the properties of galaxies including the weakest objects: the absolute magnitude M B -10 and the virial mass M vir 10 9 M x263C;. ... Luminosity function of the Local Volume galaxies. ... The luminosity functions for galaxies are presented: red dashed line - from the 2dFGRS survey (Norberg et al. 2002); blue dash-dotted line - from the SDSS survey (Blanton et al. ...

... Latest Supernovae . ... Sorted by Name For the years covered, 7501 supernovae and 114 extragalactic novae were reported. 376 of these supernovae were named by CBAT, 1714 were given possible supernova designations, and 5411 were not reported to CBAT. 219 supernovae were found in NGC/IC galaxies, 874 were found in named galaxies 341 objects were discovered by amateurs 4 were brighter than 13th Magnitude 208 were brighter than 16th Magnitude 1079 were brighter than 18th Magnitude 1349 ...

... Since the fast mode window is necessarily small, the source PSF fills much of the window (clearly evident for bright sources). ... As such, the source and background extraction apertures may be truncated by the window. ... While often there will be only one object in the image, one should check for spurious detections which could affect the analysis of the target source and also for missed sources or prominent objects in the window, which may contaminate the target. ...

... SEARCH ASP SITE: Match ALL words Match ANY word . ... Astronomy . ... Hubble Space Telescope Images: http://hubblesite.org/newscenter/newsdesk/archive/releases/image_category/ . ... The Chandra x-ray telescope (in orbit around Earth) has been sending back a wide range of images of what deep space objects would look like if seen with "x-ray sensitive" eyes. ... Web Sites for Asking Astronomy Questions . ... Ask an Astronomer for Kids: http://coolcosmos.ipac.caltech.edu/cosmic_kids/AskKids/index.shtml...

... A classic test of the standard orientation-dependent unified schemes has been the assessment of the quasar fraction in complete radio samples. Using a sample of giant radiosources (projected size ) out to redshifts of , I demonstrate that the fraction of broad line objects is smaller than that obtained by comparison of quasars and galaxies in the 3CR sample. ... The sample . ... Giant radio sources ( ) have traditionally been of great interest for several reasons. ...

In 1950 Jan Oort noticed that . no comet has been observed with an orbit that indicates that it came from interstellar space, . ... From this he proposed that comets reside in a vast cloud at the outer reaches of the solar system. ... Unfortunately, since the individual comets are so small and at such large distances, we have no direct evidence about the Oort Cloud. ... Its orbit is intermediate between the Kuiper Belt and what was previously thought to be the inner part of the Oort Cloud. ...

... The object is remarkable because of its low estimated mass and age and because it is associated with a mid-infrared source, an indication of a surrounding dusty disk. Based on the comparison of our spectrum with similar spectra of field M-dwarfs and atmospheric models, we obtain revised estimates of the spectral type, effective temperature and luminosity of the central object. ...

... no comet has been observed with an orbit that indicates that it came from interstellar space, . ... From this he proposed that comets reside in a vast cloud at the outer reaches of the solar system. ... Unfortunately, since the individual comets are so small and at such large distances, we have no direct evidence about the Oort Cloud. ... T he Kuiper Belt is a disk-shaped region past the orbit of Neptune roughly 30 to 100 AU from the Sun containing many small icy bodies. ... Small Bodies .. ...