There are three types of permissions: r read the file or directory w write to the file or directory x execute the file or search the directory . Each of these permissions can be set for any one of three types of user: u the user who owns the file (usually you) g members of the group to which the owner belongs o all other users . The access permissions for all three types of user can be given as a string of nine characters: user group others r w x r w x r w x . ...

Astronotes Armagh Planetarium's Stellar Blog! ... Our Galaxy . ... Stars . ... Other Galaxies . ... Light of other eyes, other times: The X-rays and IR radiation making up the image have been travelling for a long time. ... The inspiration here came from a new ESA image of M31, the Andromeda Galaxy, composed from two very different images. ... Our nearest galactic neighbour, the Andromeda Galaxy?s brightness is caused by the hundreds of billions of stars that are contained within. ...

Different types of satellite orbits have different uses: while the synchronous orbit is best for communication satellites, Lagrangian point orbits help monitor the solar wind before it reaches Earth. A low altitude polar orbit is widely used for monitoring the Earth because each day, as the Earth rotates below it, the entire surface is covered. ... A different choice was made for MAGSAT, orbited 1979-80 to survey the Earth's own magnetic field near its surface. ...

. ATMOSPHERIC INFLUENCE ON THE DIFFERENT RADIO-ENGINEERING . SYSTEM FUNCTIONING . The calculations of the atmospheric impact on terrestrial and satellite communication links with frequencies above 10 GHz using the ITU-R data bank. The correction of the Earth cover optical images obtained from the satellite/ . The Earth atmospheric influence on the radiowave propagation parameters in wide frequency range (from SLF to UV). Contact e-mail: . Pozhidayev Victor, Ph.D - vic@cplire.ru . © IRE RAS 1996-20 11

... Why does X-ray astronomy require satellite telescopes? ... That is why scientists use space based satellites to record and observe data from X-ray sources. ... It primarily observes X-ray sources and has a moderate imaging capabilities. ... X-rays (because of their short wavelengths) , as opposed to visual light, can penetrate through otherwise opaque objects e.g. bones X-rays can observe celestial objects that emit shorter wavelengths such as galaxies , quasars, and black holes. ... X-ray image . ...

Next: Principles of organization Up: Further advance in the Previous: Further advance in the . ... An ability of using different catalogs makes this problem considerably simpler. Lately Different attempts have been made for combining many astronomical catalogs in unified databases NED, SIMBAD, ESIS, ADS, etc.(see reviews by Andernach et al.1994; Andernach 1995). ... We propose a new solution to this problem with a ``CATalogs supporting System'' (CATS) at Special Astrophysical Observatory (SAO). ...

... Low Polar Orbit . ... Different types of satellite orbits have different uses: while the synchronous orbit is best for communication satellites, Lagrangian point orbits help monitor the solar wind before it reaches Earth. ... Many spacecraft use such orbits, e.g. the US Air Force surveillance satellites of the DMSP series, or the series of French Earth-resources spacecraft SPOT . ... If the satellite then starts near a noon-midnight orbit, it will always pass near noon and near midnight. ...

Understanding the early phases of assembly and formation of galaxies is a challenge. ... The IAU symposium 317 at the XXIX IAU GA in 2015 will take place at the verge of a revolution that is brought about by the availability of unprecedent new data, provided by the Gaia satellite, space telescopes (HST, Spitzer) and by a number of large ground-based spectroscopic and photometric surveys of the Milky Way, M31 and external galaxies. ...

Learning Astronomy Through Storytelling . That children at different stages of development will derive different meanings from the same story is obvious but worth mentioning. ... If you teach K-2, the central message of the story that you want students to understand is simply that the Moon's shape, as they see it in the sky, varies. ... Children learn that a story has a plot, a setting, characters, a main problem, a crisis point, and a solution. ...

Next: Highlights 1999 Up: Astronomy in Armagh Previous: Research Areas and Facilities Contents . In addition to its principal function as an astronomical research institute, the Armagh Observatory has a responsibility to disseminate widely the results of its astronomical research. The Observatory plays a major role in the promotion of astronomy and the public understanding of science, both locally (i.e. within Armagh City and District and Northern Ireland) and abroad. ...

... Water on Mars . ... Can you help discover water on Mars? ... Gamma Ray Earth . ... A Tether in Space . ... The strange answer leads astronomers to conclude that the nucleus of the surrounding galaxy is not even visible in this image. ... Composite Crab . ... xxxre linkxxx) The Crab Pulsar, a city-sized, magnetized neutron star spinning 30 times a second, lies at the center of this composite image of the inner region of the well-known Crab Nebula. ... Huygens Discovers Luna Saturni . ...