
	Where results make sense

Topic: Right ascension

Related Topics

Celestial coordinate system

Equatorial coordinate system

Horizontal coordinate system

Declination

Vernal equinox point

Sidereal time

First Point of Aries

Hour

Apparent magnitude

Open cluster

Upsilon Andromedae

Geographical pole

Alnitak

Castor (star)

55 Cancri

In the News (Tue 14 Feb 12)

EXECUTIVE POWER

Iran

ANALYSIS

Pakistan

Family compact

	Ascension (disambiguation) - Wikipedia, the free encyclopedia
		Generally, an ascension is the act of ascending, usually to a significantly higher personal state, as the ascension of a king to the throne.
		In astronomy, right ascension is used to describe positions in the sky.
		Ascension is a process in the Stargate universe where humans become become noncorporeal god-like entities, where they exisit on a higher plane of existence.
	en.wikipedia.org /wiki/Ascension_(disambiguation) (375 words)

	Right ascension - Wikipedia, the free encyclopedia
		Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system.
		Being closely tied with sidereal time, it is both a unit of time and of angle.
		An hour of right ascension is equal to 15 degrees of arc, a minute of right ascension equal to 15 minutes of arc, and a second of right ascension equal to 15 seconds of arc.
	en.wikipedia.org /wiki/Right_ascension (254 words)

	Celestial Coordinate System
		Right ascension can be measured in degrees, but for historical reasons it is more common to measure it in time (hours, minutes, seconds): the sky turns 360 degrees in 24 hours and therefore it must turn 15 degrees every hour; thus, 1 hour of right ascension is equivalent to 15 degrees of (apparent) sky rotation.
		The zero point for celestial longitude (that is, for right ascension) is the Vernal Equinox, which is that intersection of the ecliptic and the celestial equator near where the Sun is located in the Northern Hemisphere Spring.
		Thus, the directions get reversed: moving to the right from the vernal equinox in the first diagram will look like moving to the left as viewed from its center, which is the perspective of the second diagram (that is, the actual view of the sky from Earth).
	csep10.phys.utk.edu /astr161/lect/time/coordinates.html (700 words)

	[No title] (Site not responding. Last check: 2007-10-22)
		Right ascension (R.A.) on the sky has a similar arbitrary zero point -- it is a circle from the north celestial pole (Polaris) to the south celestial pole, that passes through the point on the sky that was directly over Greenwich, England at noon on the vernal equinox in the year 1900.
		The only difference between longitude on earth and right ascension on the sky is that longitude is usually measured in degrees (from 0 degrees to 360 degrees), while right ascension is measured in hours (from 0 hours to 24 hours).
		Earth is at the center, the lines show the various directions of right ascension, and each circle represents a distance of 1 kiloparsec from the earth.
	www.astro.psu.edu /users/rbc/a1/a1_homework6.html (595 words)

	JeffPo's Setting Circles & Celestial Coordinates Page
		Right Ascension is similar to longitude, with the difference that right ascension is measured in hour angles (zero to 24...as in 24 hours in a day) instead of degrees.
		The only other thing to remember is that as you move toward the east, the right ascension numbers increase (until you hit 24, in which case you're back to your starting point of zero hour again, i.e you've done a "360", a loop).
		So, if an object was defined as having a Right Ascension of 2h 30m and a Declination of 15d 10m N, you would start at the zero hour of right ascension on the celestial equator and move east until you reach the 2 hour, 30 minute mark.
	www.mindspring.com /~jeffpo/settingc.htm (2855 words)

	The Hipparcos Space Astrometry Mission: Selected Statistics from the Hipparcos and Tycho Catalogues
		The median correlation between right ascension and declination in equatorial coordinates.
		Median difference between right ascension from the Hipparcos Input Catalogue (after rotation to the Hipparcos reference frame) and right ascension from the Hipparcos Catalogue, in equatorial coordinates.
		Median difference between proper motion in right ascension from the Hipparcos Input Catalogue (after rotation to the Hipparcos reference frame) and proper motion in right ascension from the Hipparcos Catalogue, in equatorial coordinates.
	www.rssd.esa.int /Hipparcos/vis_stat.html (846 words)

	Right Ascension & Declination (Site not responding. Last check: 2007-10-22)
		Right Ascension (abbreviated R.A.) and Declination (abbreviated Dec) are a system of coordinates used by astronomers to keep track of where stars and galaxies are in the sky.
		Right Ascension measures the other part of a star's position.
		Right Ascension is measured in hours of time.
	liftoff.msfc.nasa.gov /academy/universe/radec.html (329 words)

	RIGHT ASCENSION (Site not responding. Last check: 2007-10-22)
		Right Ascension = hours measured along the celestial equator, starting from the March equinox (intersection of the ecliptic with the celestial equator).
		The units of right ascension are hours, since the celestial equator is divided into 24 equal portions.
		By convention, the starting point, or 0 hours of right ascension, is a point on the celestial equator called the vernal or March equinox.
	homepage.mac.com /kvmagruder/bcp/sphere/ra.htm (184 words)

	Introduction to Spherical Astronomy: p. 10 (Site not responding. Last check: 2007-10-22)
		To find the right ascension of a star follow an hour circle "straight down" from the star to the celestial equator.
		There is one oddity in right ascension: the unit used to report the angle.
		Right ascensions are always recorded in terms of hours, minutes, and seconds.
	www.physics.csbsju.edu /astro/CS/CS.10.html (184 words)

	Lab Notes
		right ascension is defined as where the plane of the Earth's orbit around the Sun (the ecliptic) crosses the celestial equator in Pisces.
		The current standard is "equinox 2000.0," shorthand for "right ascension and declination at the moment the year 2000 begins." The previous standard, still encountered on some star charts, was 1950.0.
		For moving objects such as the Sun, Moon, and planets, right ascension and declination are often given for the "equinox of date": that is, correct for the actual date listed.
	www.sas.org /E-Bulletin/2001-10-19/labNotes2/labNotes.html (1388 words)

	PY 124: Right Ascnesion (Site not responding. Last check: 2007-10-22)
		Right Ascension is a coordinate on the celestial sphere that is similar to, but not identical to, longitude on the Earth's surface.
		Right ascension measures the positions of celestial objects in an east-west direction, like longitude, but unlike longitude right ascension is a time-based coordinate.
		Right Ascension is expressed in units of time on a 24 hour format.
	www.physics.ncsu.edu /courses/astron/Right_Ascension.html (734 words)

	right ascension on Encyclopedia.com
		RIGHT ASCENSION [right ascension] in astronomy, one of the coordinates in the equatorial coordinate system.
		The right ascension of a celestial body is the angular distance measured eastward from the vernal equinox along the celestial equator to its intersection with the body's hour circle.
		The equivalents of latitude and longitude on the celestial sphere are declination and right ascension.
	www.encyclopedia.com /html/r1/rightasc.asp (398 words)

	Lecture 1: Introduction to Astronomy 250
		Right ascension is analogous to longitude, is usually measured in units of time: hours, minutes, seconds.
		The zero-point for right ascension is the Vernal Equinox (also called the Aries Point in the text), location on the celestial equator of sunrise on the first day of spring.
		Another complication with right ascension arises from the changing angular size of circles of constant right ascension when moving from the celestial equator towards the celestial pole, the circles shrink by a factor of cos(DEC) which must be taken into account.
	ircamera.as.arizona.edu /astr_250/Lectures/LECTURE_01.HTM (1457 words)

	Observing Fundamentals
		Right ascension is like longitude, and declination like latitude, on the earth, and are measured analogously.
		Right Ascension is measured in hours in the same direction, from 0 to 24 hours.
		The right ascension α and the declination δ are nearly constant for stars.
	www.du.edu /~jcalvert/astro/obsfunds.htm (2326 words)

	right ascension -- Britannica Student Encyclopedia
		Right ascension and declination define the position of a celestial...
		Based on the celestial equator and poles, the equatorial coordinates, right ascension and declination, are directly analogous to terrestrial longitude and latitude ().
		Right ascension, measured eastward from the first point of Aries (see directly above), is customarily divided into 24 hours rather than 360°, thus emphasizing the clocklike behaviour of the sphere.
	www.britannica.com /ebi/article-9063679 (844 words)

	ICRS Narrative (Site not responding. Last check: 2007-10-22)
		This reference point, the right ascension origin, has traditionally been the equinox: the point at which the Sun, in its yearly circuit of the celestial sphere, crosses the equatorial plane moving from south to north.
		The ICRS origin of right ascension was made to be consistent with that in a group of VLBI catalogs previously used by the IERS, each of which had been individually aligned to the lunar occultation right ascension of 3C 273B.
		The difference between the ICRS origin of right ascension and the dynamical equinox has been independently measured by two groups that used different definitions of the equinox, but in both cases the difference found was less than 0.1 arcsecond.
	aa.usno.navy.mil /faq/docs/ICRS_doc.html (4516 words)

	Cosmic Voyage-The Online Resource for Amateur Astronomers (Site not responding. Last check: 2007-10-22)
		You'll recall that declination is similar to latitude and that right ascension is the same as longitude.
		The motorized drive at the back end of the right ascension axis is there to allow the telescope to track objects as they move westward across the sky.
		That's because the right ascension axis needs to be aligned parallel to Earth's axis of rotation in order for the drive to work.
	members.aol.com /billferris/align3.html (1065 words)

	The 24 Inch McMath Telescope
		The right ascension drive is the fl circle on the lower left (it is partially obscured by the rest of the telescope and has several circular cutouts, it is easier to see in the following photographs).
		The eyepiece for the 6” refractor is on the left center (to the right of the 24” telescope eyepiece).
		The right ascension drive moves the telescope to compensate for the earth’s rotation.
	www.umich.edu /~lowbrows/theclub/technical.html (860 words)

	The Primary Directions to Fixed Stars
		Right ascension of 4º40' of Libra is 184º17', but Argolus says, that right ascension of the sextile of Venus is 184º22'.
		In this chart Medium Coeli is in 28º01' of Virgo; according to Argolus, right ascension of Medium Coeli is 178º11', and right ascension of Spica is 195º47'.
		Ascendant of the chart is 18º52' of Libra; according to Argolus, oblique ascension of Ascendant is 204º21', and oblique ascension of Antares (Heart of Scorpio) is 267º11'.
	www.worldastrology.net /articles/stardir.html (1974 words)

	Physics 155: Stellar Coordinates (Site not responding. Last check: 2007-10-22)
		Right ascension and declination are similar to longitude and latitude.
		Right ascension is measured around the celestial equator towards the east.
		Since the Right Ascension and Declination are relative to fixed stars, these coordinates do not change over time or with the position of the observer.
	www.sp.uconn.edu /~cynthia/defs/coords.html (423 words)

	Right Ascension / Declination (Site not responding. Last check: 2007-10-22)
		Right ascension and declination are what astronomers use to precisely locate objects on a celestial map, and are equivalent to the imaginary lines of longitude and latitiude used in maps of the earth.
		Although it is obvious that all of the stars lie at different distances from the earth, it is also convenient to think of the sky as a fixed sphere with the earth at the center.
		The earth is tilted 23.5 degrees in its orbit around the Sun, causing the path of the Sun to only cross the celestial equator during the vernal and autumnal equinoxes.
	members.ncats.net /astro/reference/ra.html (391 words)

	Setting Circles (Site not responding. Last check: 2007-10-22)
		The only other thing to remember is that as you move toward the east, the right ascension numbers increase (until you hit 24, in which case you're back to your starting point of zero hour again, i.e.
		So, if an object was defined as having a Right Ascension of 2h 30m and a Declination of 15deg 10m N, you would start at the zero hour of right ascension on the celestial equator and move east until you reach the 2 hour, 30 minute mark.
		My SCT mount actually moves the right ascension dial as it moves the telescope so once I have made the initial calibration, I don't have to readjust it.
	www.astro-tom.com /telescopes/setting_circles.htm (2278 words)

	Orion Telescopes and Binoculars - Celestial Coordinates (Site not responding. Last check: 2007-10-22)
		The right ascensions and declinations of stars are essentially fixed, although they shift very slowly because of precession, a gradual change in the direction of the Earth’s axis.
		The reason right ascension is measured in hours is of course that the celestial sphere seems to rotate as the Earth turns.
		The sidereal time at any moment is the right ascension of the point directly overhead, as well as points directly north and south of it (along a line called the meridian).
	www.telescope.com /sdx/176664.jsp (1366 words)

	[No title]
		On the map, the vernal equinox is right in the middle, while the autumnal equinox is shown at both ends of the celestial equator.
		Right ascension is measured from the vernal equinox eastward.
		Right ascensions are marked on the celestial equator and also on four lines parallel to the equator.
	www.msu.edu /~bausemic/astro/MappingPlanets.doc (867 words)

	SAO TDC ASCII Catalog Flags (Site not responding. Last check: 2007-10-22)
		Right ascension is in fractional hours; declination is in fractional degrees.
		Positions are right ascension and declination as hh.mmssss and dd.mmssss or hh:mm:ss.sss and dd:mm:ss.sss.
		Positions are right ascension as hh mm ss.sss dd mm ss.sss.
	tdc-www.harvard.edu /catalogs/catalogsa.flags.html (346 words)

	Introduction to terminology (Site not responding. Last check: 2007-10-22)
		For most practical purposes, you'll be looking up the right ascension and declination of stars on a star chart or in a list.
		One hour of right ascension equals 15 degrees, so right ascensions run from zero to 24 hours.
		Furthermore, hours of right ascension are often divided up into minutes and seconds, so you have to be careful in distinguishing seconds of angle (which come 3600 to a degree) from seconds of right ascension (which come 3600 to an hour).
	www.astronexus.com /armchair/3d/terms.html (1403 words)

	ASTRONOMY 100 HOMEPAGE - STARDIAL
		("Right ascension" is the celestial equivalent of "longitude".
		It increases toward the east.) For example, 02010430.jpg is a picture taken on Feb 1 at the right ascension 04h30m.
		Examine the image at right ascension 11h00m taken on Feb 2, 1998, and the image at the same right ascension but taken on Feb 6, 1998.
	www.astro.uiuc.edu /~chu/astro100/stardial.html (671 words)

Try your search on: Qwika (all wikis)