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	Apparent magnitude - Wikipedia, the free encyclopedia
		The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness.
		The rate at which apparent brightness changes, as the distance from an object increases, is calculated by the inverse-square law (at cosmological distance scales, this is no longer quite true because of the curvature of space).
		The second thing to notice is that the scale is logarithmic: the relative brightness of two objects is determined by the difference of their magnitudes.
	en.wikipedia.org /wiki/Apparent_magnitude (1115 words)

	What Is Visual Magnitude? (Site not responding. Last check: 2007-10-07)
		"Visual magnitude" is a scale used by astronomers to measure the brightness of a star.
		The term "visual" means the brightness is being measured in the visible part of the spectrum, the part you can see with your eye (usually around 5500 angstroms).
		The brightness of a star depends not only on how bright it actually is, but also on how far away it is. For example, a street light appears very bright directly underneath it, but not as bright if it's 1/2 a mile away down the road.
	liftoff.msfc.nasa.gov /academy/universe/MAG.HTML (385 words)

	Stellar Magnitudes
		The former is a convolution of the true brightness and the effect of distance on the observed brightness, because the intensity of light from a source decreases as the square of the distance (the inverse square law).
		The apparent magnitude of various objects determined using light from the visible part of the spectrum is given in the adjacent table.
		The brightness of an object (whether apparent or absolute) depends on the wavelength at which we observe it, as we saw clearly in the discussion of radiation laws.
	csep10.phys.utk.edu /astr162/lect/stars/magnitudes.html (802 words)

	Messier Object 39
		Its apparent visual brightness of 4.6 magnitudes (e.g., Sky Catalogue 2000.0, Uranometria 2000) corresponds to an absolute magnitude of -2.5, or an intrinsic luminosity of 830 suns.
		Kenneth Glyn Jones gives its apparent visual brightness as 5.2 mag only, while Don Machholz has estimated it at mag 5.4, in agreement with estimates quoted by Mallas/Kreimer, who also mention D.F. Gray's estimate of a total visual brightness of 6.0 magnitudes.
		M39's brightest star is of magnitude 6.83 visually, and of spectral type A0.
	www.seds.org /messier/m/m039.html (434 words)

	M96 (Site not responding. Last check: 2007-10-07)
		At this distance, the apparent diameter of its brighter central region, 6 arc minutes, corresponds to a linear dimension of 66,000 light years.
		According to J.D. Wray's Color Atlas of Galaxies, the bright inner disk is composed of a smooth yellow stellar population of old stars, which ends slightly beyond a ring of blue knots.
		A bright supernova, SN 1998bu, was discovered by Mirko Villi on May 9, 1998 at 13th magnitude and was quickly brightening to 11.8 mag.
	www.intercom.net /user/shaffer/messier/m96.html (384 words)

	About Schaefer (Site not responding. Last check: 2007-10-07)
		The "visual" magnitude, V, is measured with a filter with peak transmission at 550 nm (5500 Å), matching the combined sensitivity of the cones of the eye that are responsible for day vision.
		The apparent star brightness is determined mainly by the area of the aperture, and the lss is determined mainly by the area of the aperture, and the light collected will be "squeezed" into a thin pencil beam (the exit pupil) going into your eye.
		The background brightness comes largely from sunlight scattered by dust within the solar system, with contributions from skyglow, that is from ionized gas in the upper atmosphere, and also from the unresolved star background from the Milky Way.
	www.bbastrodesigns.com /visual/nils/Schaefer.html (3541 words)

	Magnitude
		Apparent magnitude is the brightness of an object as it appears to an observer on Earth.
		The apparent magnitude discussed so far, that is the brightness as seen from the Earth, depends on both the intrinsic luminosity and the distance of objects.
		The term "apparent magnitude" is usually taken to mean apparent visual magnitude, the relative brightness as seen by the human eye.
	www.historyoftheuniverse.com /magnitude.html (618 words)

	Apparent magnitude (Site not responding. Last check: 2007-10-07)
		The apparent magnitude of a star, planet or other heavenly body is a measure of its brightness as seen from Earth.
		In 1856, Norman R. Pogson[?] noticed that the traditional system could be approximated by assuming that a difference of one magnitude corresponds to a brightness ratio equal to the fifth root of 100, so that a typical first magnitude star is 100 times brighter than a typical sixth magnitude star.
		On photographic film, the relative brightnesses of the blue supergiant Rigel and the red supergiant Betelgeuse are reversed compared to what our eyes see since film is more sensitive to blue light than it is to red light.
	www.freetemplate.ws /ap/apparent-magnitude.html (656 words)

	Magnitude Summary (Site not responding. Last check: 2007-10-07)
		apparent visual brightness of a star on the sky
		visual brightness the star would have if it were at 10 pc.
		total brightness (all wavelengths) of a star if it were at 10 pc.
	astrosun.tn.cornell.edu /academics/courses/astro101/1998/lecture07/tsld007.htm (34 words)

	Stellar brightness (Luminosity) (Site not responding. Last check: 2007-10-07)
		Brightness is related to the energy we detect
		D One and a half billion years later, the surface of the Sun is 3.3 times the size it is now, and its temperature about 4300 degrees.
		This is the end of the solar system: A fl dwarf, with the ashes of the planets circling around it.
	www.d.umn.edu /~hmooers/astro/Stellar_brightness.htm (617 words)

	Optics for Astronomy
		The magnification, M, is defined as the ratio of the apparent to actual angular separation of the stars.
		Since we will not be determining the brightness in absolute flux units but in terms of relative brightness, we will define the "light gathering power" in terms of the square of the diameter of the objective.
		This means that the brightness of the image is proportional to the square of the diameter of the objective lens and inversely proportional to the square of the focal length.
	plato.acadiau.ca /courses/phys/1513/optics.htm (1501 words)

	Video Meteor Observation with MOVIE
		On the IMC '95 it was shown that plottings of even inexperienced visual observers result in quite accurate radiant positions ([3],[4]) even though the errors of individual meteors are relatively big.
		Another problem are meteor brightness estimates: As described in [5] we have recognised a constant shift of 0,5 to 1 mag of visual estimates based on double observations with MOVIE in summer '94 (i.e.
		It should be mentioned that all visual estimates were done in 1 mag steps whereas the video brightness was computed with a resolution of 0,1 mag.
	www.molau.de /meteore/bright.html (1069 words)

	Messier Object 9 (Site not responding. Last check: 2007-10-07)
		To the north and west, its light is significantly dimmed by interstellar dust, as it lies at the edge of a patch of dark nebula (Barnard 64); its light is probably weakened by at least one magnitude (a factor of about 2.5).
		Taking these facts into account, the apparent visual brightness of this cluster of 7.7 magnitudes corresponds to an absolute brightness of -8.04 Mag, or a luminosity of roughly 120,000 times that of our sun.
		Visually it appeared oval to Mallas, and the ellipticity of 9 mentioned by Shapley can be seen in our photograph also.
	www.moonguy.com /messier/m/m009.html (483 words)

	Astronomy Picture of the Day 8-11-03
		This phenomenon is apparently a result of a mixture of emission light from the hottest gas, together with reflections of the bright star light from the dust in this region.
		While the bright nebula seems to be roughly 15 light years in extension, the total gaseous cloud, including low-luminosity material, seems to extend to at least 40 light years.
		As for many diffuse nebulae, the overall brightness of this object is difficult to estimate, and is given discordantly in the sources.
	www.freerepublic.com /focus/f-chat/961746/posts (773 words)

	Basic Astrophysics
		The most apparent property of a star in the sky is its brightness.
		The apparent magnitude is the brightness of a star as seen on Earth.
		Of course, few stars are at that distance from Earth, and it's certainly not possible to move a star to that distance just to get a magnitude measurement, so in nearly all cases the figure for the absolute magnitude of a star is a guess based on other measured properties of the star.
	hexadecimal.uoregon.edu /relativity/astro.html (879 words)

	CfAO - Adaptive Optics Demonstrators - Glossary (Site not responding. Last check: 2007-10-07)
		It consists of a central bright source with light and dark circular fringes around it.
		Guide star: A bright star near the target object which the wavefront sensor uses to measure the distortions in the wavefronts.
		The mirror is moved to counteract the apparent motion of a star.
	www.ucolick.org /~aodemos/home/glossary.html (409 words)

	[No title]
		In astronomy the brightness of an object is described by a number called its magnitude.
		The apparent magnitude of an object is simply a measure of the amount of light received from the object.
		The absolute magnitude of an object is the apparent magnitude the object would have if it were 10 parsecs from the Earth.
	www.csulb.edu /~gordon/astdocs/25.doc (454 words)

	SETI : Turotial/Measuring Time and Distance
		Absolute brightness tells us how luminous, or bright, a star is; however, we usually see stars at different distances; two stars with equal absolute brightness but at different distances will appear with different apparent brightness; the closer one will appear brighter than the one further away.
		For historical reasons, astronomers don't give the brightness of a star in energy ejected per second, but rather they use a somewhat arcane way of classifying the brightness of stars.
		There is a correction factor that takes into account that visual magnitude gives the luminosity in the visible part of the spectrum, while the star also emits at both lower and higher wavelengths.
	www.phy.syr.edu /courses/CCD_NEW/seti/tutorial/measure/part6.html (950 words)

	AstroHobby.com -- Star Magnitudes and Counting the Stars in the Sky
		Stars can be classified by their "apparent" visual brightness, their brightness as seen from the Earth.
		Modern measurements of their brightness indicated that the stars in the first group were two to three times brighter than the stars in the second group.
		On this scale, stars which differ by five magnitudes have a brightness ratio of 100, and, therefore, stars which differ by one magnitude have a brightness ratio of 2.512 (= the fifth root of 100).
	www.panix.com /~ddellutr/astro/smacts.htm (834 words)

	Achernar (Site not responding. Last check: 2007-10-07)
		Achernar (α Eri / α Eridani / Alpha Eridani) is the brightest star in the constellation Eridanus and the ninth brightest star in the nighttime sky.
		Achernar is a bright supergiant star visible in the southern part of the night sky.
		Apparent Visual Brightness (Sirius A = 1): 0.175
	www.worldhistory.com /wiki/A/Achernar.htm (250 words)

	Lecture 11: The Brightness of Stars
		The brightness of a source is inversely proportional to the surface area of the wavefront, where "d" is the distance from the source to the observer.
		These apparent magnitudes are measured with a filter which only allows Visible light with wavelength close to 550 nm to pass through to the detector.
		V is used to denote apparent Visual magnitude instead of m sometimes.
	www.phys.ualberta.ca /~morsink/astro122/lectures/lect11/lecture11.html (655 words)

	Star positions (Site not responding. Last check: 2007-10-07)
		Dec (Declination) Declination is the star's angle north or south of Earth's celestial equator, ranging from -90 degrees at the south celestial pole to +90 degrees at the north celestial pole.
		Mag (Magnitude) The apparent visual magnitude (brightness to an observer on Earth) this star would have if it were at a distance of exactly 10 parsecs (32.64 light-years).
		Note that the magnitude scale decreases with brightness; a star of magnitude +6.0 would be 100 times dimmer than a star of magnitude +1.0.
	astronomy.swin.edu.au /~pbourke/modelling/starpositions (245 words)

	Spica (Site not responding. Last check: 2007-10-07)
		Its apparent magnitude varies between +0,92 and +0,98, with a period of 4.0142 days.
		An easy way to find Spica is to follow the arc of the handle of the Big Dipper to Arcturus, and then continue on the same distance to Spica.
		Apparent Visual Brightness (Sirius A = 1): 0.108
	www.worldhistory.com /wiki/S/Spica.htm (360 words)

	[No title] (Site not responding. Last check: 2007-10-07)
		A constellation is a visual grouping of stars that forms a pattern.
		Brightness may be defined as the amount of radiant energy received from a light source per second.
		Apparent brightness is the brightness of an object as seen from the Earth.
	www.tcnj.edu /~pfeiffer/AST161chap5.html (2271 words)

	Deepsky Visual Brightness Calculator
		This is the mean average luminosity of all 1 "square" arc-minute regions on the object.
		Adjusted Surface Brightness: Since the luminosity of many deepsky objects tends to coelesce around certain brighter regions, this is the expected luminosity of the brightest portions.
		This effect is offset however, by the fact that sky brightness also increases with lower magnification.
	astro.geekjoy.com /calcs/surfbright.html (166 words)

	Brightness of stars (Site not responding. Last check: 2007-10-07)
		Response #: 2 of 2 Author: hawley The brightness of stars as seen from the Earth is called "apparent visual magnitude"; it is designated by "m subscript v" and is a logarithmic scale like the Richter scale used for earthquakes.
		The brightest star seen from the Earth's northern hemisphere is Sirius, the Dog Star with a _m subscript v_ of -1.5 (the stellar magnitude scale is one in which a negative number is brighter than a positive number).
		The absolute visual magnitude, designated by "M subscript v", gives the true brightness: Deneb (alpha Cygnus) has Mv = -6.9, and Rigel (beta Orion) is almost as bright with Mv = -6.8.
	www.newton.dep.anl.gov /newton/askasci/1995/astron/AST162.HTM (254 words)

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