... Four types of galaxy environments are considered: clusters, centers of groups, other places in groups, and the field. ... In order to check whether the mean ages of the stellar populations depend on environment density monotonically, as the hierarchical par­ adigm predicts, in this work I consider four types of environment separately: the cluster galaxies, the brightest (central ) galaxies of groups, the second­ranked group members, and the field galaxies. ... Group center SB(rs)0# 204 637 1996 Oct ...

... Bad Astronomy . ... Bitesize Astronomy . ... Here's a question for you: if you were to place the Moon randomly anywhere in the sky, on average, how many stars would it cover up? ... We found that the sky is about 40,000 square degrees . ... The area of a circle is pi * radius^2, so the Moon's area is pi * (1/4)^2=0.2 square degrees. So the number of stars in an area the size of the Moon is 0.15 stars/square degree * 0.2 square degrees=0.03 stars per Moon area. ... 2008 Phil Plait. ...

Change in Brightness Kepler 4b 0.0 % - 0.1 %0.12 - 0.2 % 0.14 0.16 0.18 0.02 0.04 0.06 0.08 Transit Light Curves Set 1 Transit Tracks p. 3 2 4 6 8 10 12 14 16 Time (in days ) 18 20 22 24 26 Change in Brightness HAT-P-7b 0.0 % -1.0% -2.0% 0.2 0.4 0.6 0.8 1.2 1.4 1.6 1.8 2.2 2.4 2.6 2 4 6 8 10 12 14 16 Time (in days ) 18 20 22 24 26 Change in Brightness HAT-P-11b 0.0 % -0.5% -1.0% ...

... Imaging GRIN Rod Lens (HAG's) | Relay Rod Lens (LAG's) | ... The Refractive Index Distributions (RID) in GRIN lens preforms are made by multi-stage optimized ion-exchange diffusion between silicate mineral glasses and salt melts. ... In the LAG lenses - L ow A perture GRIN the nature of the changing of refractive index in glass via ion-exchange lies mainly in molecular volume increase. ... LAG lenses are specially treated to create the dark anti-flick surface coating (Fig.2). ...

... Telescopes . ... LS Series . Meade's revolutionary LS LightSwitchтДв series of telescopes use advanced technologies to do what no other consumer telescopes have done before: take all the hassle out of using a telescope. ... ETX Series . ... Back Cell Adapter - ETX to SCT Thread . ... Allows accessories that require a SCT thread to be attached to the ETX series of telescopes, including focal reduces and off-axis guiders. ... Allows accessories that need SCT threading to be attached to ETX series . ...

... The Magazine . ... Get to Know the Night Sky . ... Cosmic particle accelerators get things going . Cluster has shown that narrow shocks may be vital to kick-starting the acceleration process in exploding stars, young stars, black holes, and whole galaxies. ... For example, the Large Hadron Collider at CERN employs a series of small accelerators to get its particles up to speed before injecting them into the main 17-mile-circumference (27 kilometers) ring for further acceleration. ...

... Comets and Asteroids . ... Earth Satellites . ... Illustration of how NASA could capture an asteroid . ... The meteor was quite small compared to some of the objects out there that could potentially hit the Earth, thus if we understood asteroids it could be potentially life-saving! ... This mission could start as soon as the early 2020s with NASA already simulating an asteroid mission to figure out how astronauts might undertake a spacewalk on it. ... Can NASA lasso an asteroid back to Earth? ...

... 000, 1­12 (2009) Printed 11 February 2010 A (MN L TEX style file v2.2) Analytical approximations of K -corrections in optical and near-infrared bands I1gor V. Chilingarian1 2 ,2,3 , Anne-Laure Melchior 1,4 and Ivan Yu. ... Received 2010 February 01; in original form 2009 August 14 ABSTRACT To compare photometric properties of galaxies at different redshifts, the fluxes need to be corrected for the changes of effective rest-frame wavelengths of filter bandpasses, called K -corrections. ... Table 1. ...

Using Site testing data for Adaptive Optics simulations Kislovodsk, October 2010 1Glen Herriot, 1David Andersen, 1Jean-Pierre VИran, 2Brent Ellerbroek, 2Luc Gilles, 2Lianqi Wang 1National Research Council Canada ­ Herzberg Institute of Astrophysics 2TMT Project Office, Pasadena TMT.AOS.PRE.10.074.REL01 1 Outline TMT / NFIRAOS Site Testing Parameters and their value for Adaptive Optics Simulations ... TMT.AOS.PRE.10.074.REL01 9 What is the interest of Adaptive Optics in r 0 Seeing ? ...

... Home Articles Best Celestial Events of 2006 . ... Clear Sky Chart . ... Beyond New York City . ... Best Celestial Events of 2006 . ... Observing Resources for Amateur Astronomers - Part 1: Beginning Observers . Observing Resources for Amateur Astronomers - Part 2: Intermediate Observers . ... A History of the First Forty Years of the Amateur Astronomers Association . ... Amateur Astronomers Medal . ... 2016 Amateur Astronomers Association of New York Designed by Press Customizr Powered by . ...

... The spectrum of the brightest star, our Sun, shows several dark gaps perpendicular to the flow of it’s colours (figure 1). These so called spectral absorption lines where discovered in 1802 by the English scientist William Wollaston. ... Some stars as Pollux show a spectrum similar to that of our sun with strong Ca II and Fe II lines, others as Sirius or Vega show strong absorption lines of hydrogen, others, as Mira show very complicated spectra due to molecular absorption lines (see figure 5). ...