... 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....

The "ring of fire" seen by satellite cameras around the polar caps (picture below) is probably created by electrons leaking from the tail's plasma sheet, whose magnetic field lines form a somewhat imperfect trap. ... One possible explanation involves the close association between auroral arcs and electric currents which flow along field lines between the ionosphere and distant space ( Birkeland currents ). ... That produces an extra resistance to the flow of current. ...

... Where we have just a single image we assume a probabilistic mode of source detection such that, at a given image pixel, if the probability that the observed value at that pixel could have arisen through statistical fluctuation of the background at that pixel lies below a certain limiting probability , the pixel is considered to contain a source. In XMM practice it is likelihood rather than itself which is employed; in this case the detection criterion is for to exceed the cutoff . ...

... Galaxies 99 Cosmic background with model of cloudy interstellar medium Yu. ... Figure 1: Averaged spectrum of the cosmic background I f in frequency range 0.25 200 MHz for the Galactic poles. ... First interpretation of the cosmic noise background spectrum at broad band frequency range 0.25 200 MHz with a model of the cloudy interstellar medium ISM is presented here. ... Synthesized background spectra I f for regions of the Galactic poles at the frequency range 0.25 200 MHz is presented in Fig. ...

ATMoB "Open Cluster Observing Award " Guidelines Purpose: To promote observing among the membership of the Amateur Telescope Makers of Boston through participation in the Open Clusters Observing Awards program. Introduction: This awards program is oriented towards visually observing open clusters above magnitude 9.9. ... It turns out that a very unprejudiced and convenient method to dermine the limiting magnitude is to count the number of visible stars in certain areas on the sky. ...

Appendix C Radiative Transfer for a Two-Level System This appendix details how to derive the total column density of a linear rigid-rotor molecule, such as CO, from the observed brightness of its rotational transition. ... C.2 Radiative Transfer for a Two-Level System I now consider emission in a two-level system from an upper J + 1 (denoted `u') to lower J (denoted `l') state. ... Spontaneous emission is controlled by the A coefficient, with a rate Aul nu . ... Tex exp(-31. ...

... MASTER Net is 56 square degrees per 1 exposition . ... 06 Dec 2015: GRB 151205B: MASTER-NET early optical observations GCN18665 . ... 18 Nov 2015: GRB 151118A: MASTER-NET optical observations GCN18613 . ... 12 Nov 2015: GRB 151112A: MASTER-NET optical limit GCN18591 . ... 07 Nov 2015: GRB 151107A: MASTER-NET optical observations GCN18565 . ... 31 Oct 2015: Five OTs detected by Global Robotic MASTER Net ATel8232 . ... 02 Oct 2015: GRB 151001B: MASTER-NET early optical observations GCN18380 . ...

... The bright supernova (hereafter SN) in the galaxy NGC 4527 was first sighted by S. Knight (USA) on April 13.17UT at magnitude ~14.0v. The report of the sighting was subsequently forwarded by phone to the AAVSO. ... SN 1991T. The galaxy NGC 4527 is an Sb(s)II type galaxy with an apparent Blue magnitude of 11.32 (Shapley-Ames, 1981). ... An analysis of this event utilizing visual observations by amateurs, plus a light curve is presented.. ... THE LIGHT CURVE: . ... ISN SN 1991T web page . ...

Next: Star Formation Rate and Up: No Title Previous: Calculation of Evolutionary Tracks . To start calculations, we choose the distributions of the initial binary parameters: the mass of the primary ZAMS component, , binary mass ratio, , orbital separation a . ... whereas the mass ratio distribution is not. ... The zero assumption often made is that the mass ratio distribution has a flat shape, that is binaries with a high mass ratio occur as frequently as those with equal masses. ...

... Dept. for Astrometry & Space Geodynamics . ... Dept. for Physics of Stars&Galaxies . ... Dept. for Physics of Planetary Systems . ... Science . ... All Pages . ... Research of the stars with planets which pass apparent star disk (transiting exoplanets). The transit method based on a detection star brightness decrease during a passing of planet in front of its disk. Observed brightness system decries when planet pass star disk and its volume depend of the relative sizes star and planet. ...

... There is an opportunity to perform O-C calculations for objects which are absent in the data base of the package. Such objects can be described by orbital elements or by initial coordinates and velocities. ... On pressing Edit file button user has a possibility to look through the list of object elements or their coordinates and velocities to add or to change it. ... For example, the designations of objects in the list can occupy the last position in each line. ...

NMW survey overview . Access image archive . ... The New Milky Way survey aims to detect bright (V<13.5) optical transients near the Galactic plane using an automated wide-field (8x6 deg.) system capable of surveying the whole Milky Way area visible from the observing site in one night. ... All images obtained during the transient search survey are available online (please use the image archive access form ). ... Images per field: . ... Images per night: . ... Milky Way imaging time: . ...

... This is possible at modest cost due to the low moments of inertia of the telescope and enclosure. ... This same performance will be achieved in higher winds when the telescope enclosure is facing away from the wind, or by using wind screens. ... The telescope system (MILT) will be remotely operable with an on-site operator's assistance by an astronomer located at one of the ARC member institutions. ... Mean Wind Speed . ... Offsets > 10 deg: 1 arc sec rms max . ... 5 sec max, tracking to tracking . ...

Russian version of HP . ... StarCalc is the fastest professional astronomy planetarium & star mapping program for Windows 9x/ME/NT/2000/XP (StarCalc version for PocketPC computers you can found here ). ... Extensibility : This program is based on common "Plugin StarCalc interface to catalogs and object groups", which allows program to add new modules as Plugins. ... Welcome to the Pocket StarCalc Home Page: . ... Some bugfixes in eclipses" and line" plugins - see the new versions in downloads page. ...

... The first task assumes the searching for chemical composition and sizes of particles which give the wavelength dependence of the extinction efficiencies close to the observed dependence of . Figure 7: Wavelength dependence of the extinction efficiency factors for homogeneous spherical particles of different sizes consisting of astronomical silicate and amorphous carbon. The dashed segment shows the approximate wavelength dependence of the mean galactic extinction curve at optical wavelengths. ...

... 13, Moscow 119992, Russian Federation, e-mail: busarev@sai.msu.ru; 2 Research Institute Crimean Astrophysical Observatory, p/o Nauchnyi, Crimea 334413, Ukraine, e-mail: prok@crao.crimea.ua Summary: We propose a combined method of astronomical investigations of small or distant planets incorporating registration of a set of integral spectra of an object and their frequency analysis. ... An application of the method is shown on example of asteroid 21 Lutetia. ... 6] Busarev V. V. (2002), Solar Sys. ...

Finding Himalia, The Fifth Brightest Moon Of Jupiter . Articles | ... Himalia is the only moon other than the Galilean moons of Jupiter that is visible in an amateur size telescope. ... I normally use “The Sky” from Software Bisque for planning my observing sessions and in helping me find objects, but it only has the Galilean moons for Jupiter so I used Red Shift (version 3 at the time) which I also had on my computer. ... www.astronomy.net . ... dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET" . ...

BRIGHT OPTICAL FLASH FROM GRB 060117 - AN EXAMPLE OF EVENT DETECTED WITH OMC CLASS INSTRUMENT Д Д Petr Kubanek1,2 , Martin JelД inek3 , Michael Prouza4,5,6 , Rene Hudec1 , and Martin Nekola1 1 Astronomicky ustav Akademie ved Ceske republiky, Ondrejov, Czech Republic ДД Д 2 INTEGRAL Science Data Center, Chemin d'Ecogia 16, Versoix, Switzerland 3 Instituto de AstrofД isica de AndalucД (IAA-CSIC), Granada, Spain ... INTEGRAL GRBs are detected during -ray observations of knows sources. ...

Astronotes Armagh Planetarium's Stellar Blog! ... Space Flight . ... Earth Satellites . ... Leonid meteors seen from 13 km altitude aboard an aircraft during the 1999 Leonids Multi-Instrument Aircraft Campaign (Leonid-MAC). Comet Tempel-Tuttle provides the cometary debris for the Leonid meteor shower. ... Every 17-19 November Earth crosses Tempel-TuttleтАЩs orbit and the Leonids become visible. With clear, dark skies observers may see 10 to 15 Leonid meteors every hour on those mornings. ...

... 12c. Venus transit (1) . 12d. Venus transit (2) . 12e. Venus transit (3) . ... 1 The 2004 Venus transit . ... Kepler's third law allows one to evaluate the dimensions of the solar system in relative units, e.g. in " astronomical units " (AUs), where 1 AU is the mean Sun-Earth distance. ... Edmond Halley suggested using the transit of Venus across the Sun's disk, when it appears as a dark round spot --or to quote one observer of the 2004 transit, "like a blueberry in front of an orange." ...