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Arc second

Astronomy  Arc minutes  Archeoastronomy

Arc second ('')
See Measures of angle
Astronomical unit (AU)
The mean distance between the Earth and the Sun. Length is 149,597,870 kilometres or about 150 million km (93 million miles).

Arc second: Another measure of angular separation, - one sixtieth of an arc minute. (1/3600th of a degree.)
Array: A collection of two or more individual antennas that function together as one instrument. Interferometers form one subclass of arrays.

arc second (17) 1"60th of a minute of arc.
array detector (67) Device for collecting and recording electromagnetic radiation using multiple individual detectors arrayed on the surface of a chip, for example a CCD electronic camera.

Arc second - A measure equal to one-sixtieth of an arc-minute.
Asterism - A group of stars that appear to make a recognizable shape, such as the Big Dipper.

Arc Second
A unit of angular measure consisting of 1/60th of an arc-minute. A dime seen from a distance of 2 miles transects 1 arc second. There are 3,600 arc-seconds in a one-degree angle. It is used to measure the separations of double stars or small deep-sky objects, like planetary nebulas.

An arc second is equal to one-sixtieth of an arc-minute.

arc second A unit of angular measure of which there are 60 in 1 arc minute (or therefore 3600 in 1 arc degree).
astronomy Branch of science dedicated to the study of everything in the universe that lies above Earth's atmosphere.

1 arc second = 0.0175 3600 = 4.85 10-6 rad.
Since d = R/q, d = 1.496 1011 4.85 10-6 = 3.09 1016 m
1 light year = 9.46 x 1015 m ...

One arc second is 1/60 of an arc minute and 1/3600 of an arc degree. The apparent size of a dime about 3.7 kilometers (2.3 miles) away would be an arc second. The angular diameter of Jupiter varies from about 30 to 50 arc seconds, depending on its distance from Earth.
Astronomer ...

9. An arc second is _____ (give the fraction) of an arc minute. HINT
10. When the Sun, Earth, and Moon are positioned to form a right angle at Earth, the Moon is seen in the _____ phase. HINT
11. A _____ eclipse can be seen by about half of Earth at once.

Instead it is always measured in arc seconds (remember one arc second is 1/3600 of a degree, a very small angle indeed). We know that the size of the parallax shift is related to the distance of the star, so you can use the following relation ...

arc second a tiny angle unit = 1/3600th of a degree = 1/60th of an arc minute. asteroid boulder to mountain-sized piece of rock remaining from the early solar system. The largest asteroid is only 1000 kilometers across but most are much smaller.

Arc minutes are further divided into arc seconds, such that there 60 x 60 or 3600 arc seconds per degree. So the moon's apparent size can also be expressed as 1/2 degree x 3600 = 1800 arc seconds.

For comet orbit computations, astrometry good to 1" or 2" (1 or 2 arc seconds), or better, is the standard nowadays.
ASTRONOMICAL UNIT: A unit of distance equal to the average spacing between the Earth and the Sun. Usually abbreviated A.U.

parsec Unit of distance corresponding to the distance of a body whose parallax equals one arc second. partial eclipse Pauli exclusion principle peculiar galaxy abnormally shaped galaxy that emits nonthermal radiation.

For example a 1 meter diameter optical telescope is two million times bigger than the wavelength of light observed giving it a resolution of a few arc seconds, whereas a radio telescope "dish" many times that size may, depending on the wavelength observed, ...

So with Hubble you are going to get tenths of an arc second. But with Chandra you're still getting half an arc second of resolution, which is better than most ground-based telescopes can get.

The nearest stars have an annual parallax of less than 1 arc second. In contrast, the diameter of the Sun on the sky is 32 arc minutes, the diameter on the sky of Venus at inferior conjunction is 1 arc minute,2 the diameter on the sky of Jupiter at opposition is 47 arc seconds, ...

Due to the high spatial (1 arc second) and temporal resolution (1-5sec), TRACE has been able to capture highly detailed images of coronal structures, whilst SOHO provides the global (lower resolution) picture of the Sun.

Generally credited to astronomer Herbert Hall Turner (1860-1930), the term "parsec" (pc) -- a contraction of "parallax second" -- is a unit of distance used by astronomers since at least the early 1900s, that is derived from a "parallax of one arc second.

The nebula lies in the Orion "A" molecular cloud complex and is notable for a dark T-shaped cavity located centrally in the nebula, about 20 arc seconds southwest of V380 Orionis. The small dark cloud is designated "Parsamian 34" and its nature is controversial.

The resolving power of a telescope can be calculated with the following formula: Resolving power (in arc seconds) = 4.56 - aperture of telescope (in inches). In metric units, this is: Resolving power (in arc seconds) = 116 - aperture of telescope (in millimeters).

Scotti reported at least five condensations in a long, narrow train about 47 arc seconds in length and about 11 arc seconds in width. He also discovered dust trails extending 4.20 arc minutes to the east and 6.

3 arc seconds. The brighter star, Hadar A, is a spectroscopic binary itself. Hadar A is composed of a pair of identical stars with an orbital period of 357 days. At least one of the stars is a Beta Cephei type variable, a star whose brightness varies as a result of the pulsations of its surface.

Venus is only 12 arc seconds in diameter, and Mars is even smaller, at less than 5 arc seconds. These planets are comparable in size to very small craters on the moon. The lunar surface should be partially lit up by earthlight, sunlight reflected off the planet Earth.

31 pc, which means that even the nearest star shows a parallax shift of less than one arc second. Parallax measurements can be obtained out to distances of about 20 pc. Almost all the stars you see in the night sky are at greater distances than that.

The two stars are separated by 0.86 arc seconds corresponding to a distance of of 22 AU, that is, slightly more than the separation of the sun from Uranus. The stars revolve with a period of 88 years.
Other Designations For This Star
Flamsteed ...

By using the formula Couteau provides, all variables (ball bearing radius, distance between the lamps, distance from lamps to ball bearing, and distance from telescope objective to ball bearing) are used to define the separation of the artificial pair in arc seconds.

Due to its larger orbit there are times when Mars is very close to Earth and the angular diameter can be as large as 25 arc seconds.

Chandra has an angular resolution of 0.5 arc seconds, so about 10 years.
"It's Praxis, sir."
[...] science goodness: Neutron star racing across space Graphene may make for an efficient way to make salt water into fresh Nice way to explain the [...] ...

The nearest star will only move less than one arc second. This is about one two thousandth (0.0005) of the Moon's diameter. This small change was measured near the end of the 19th century and we finally knew how far away are the nearest stars.

The field of view is usually specified as an angle that depends on the size of the sensor. For example, a lens or telescope of 500mm focal length will cover a field of view of 4 degrees, 17 arc minutes, 43 arc seconds by 2 degrees 51 arc minutes, ...

HETE-2 will be able to pinpoint the location of the burst to a circle of 10 arc seconds or about 1 / 200 the size of the Full Moon. This is around 10 times better than any previous detector.

The star with the largest known proper motion across the sky. It moves at a rate of about 10 arc seconds per year.
A spiral galaxy in which the arms originate from the ends of linear extensions to the nucleus, rather than from the nucleus itself.

In medieval Islamic astronomy, the Zij-i Ilkhani compiled at the Maragheh observatory set the precession of the equinoxes at 51 arc seconds per annum, which is very close to the modern value of 50.2 arc seconds.

Superimposed on the 26,000-year precession is a small nodding motion with a period of 18.6 years and an amplitude of 9.2 arc seconds.

Many new stargazers have trouble understanding our reference to 'degrees', 'arc minutes', and 'arc seconds' when talking about the separation of celestial objects. So here's a primer on measuring angular distances.

A unit of angular measure equal to 60 arc minutes or 3600 arc seconds. One degree is equal to the diameter of two full Moons.
The amount of mass per unit of volume.

The rate at which a star moves across the sky. Measured in arc seconds per year.
A positively charged atomic particle contained in the nucleus of an atom. The nucleus of hydrogen atom.

050 arc seconds) third after Barnard's Star and Kapteyn's Star. In only 511 years it shifts its position by one degree. It's 28.8 light years away, and has a space velocity of 312 km/s. Its Epoch 2000 values are: right ascension 11h, 52m, 58.7s; declination +37 degrees, 43', 07".

"Calculations complied from these events have made it possible to determine the Sun's diameter to several hundredths of an arc second." He follows up this data with: "Twenty years of data has shown us that the Sun may be shrinking." ...

In the area of astronomy, proper motion is the term used to describe a star's apparent movement across the celestial sphere, usually measured in arc seconds per year. The symbol for proper motion is the Greek letter μ - mu.

Hubble's Wide Field Planetary Camera 2 was used in October 1996 to undertake a sensitive search for the optical object, and found a stellar pinpoint of light within only 2 arc seconds (1/900th the diameter of the Moon) of the X-ray position.

Astrometry. The careful, precise measurement of astronomical objects, usually made with respect to standard catalogues of star positions. For comet orbit computations, astrometry good to 1" or 2" (1 or 2 arc seconds), or better, is the standard nowadays.

Two images of 2010 ST3 (circled in green) taken by PS1 about 15 minutes apart on the night of 16 September show the asteroid moving against the background field of stars and galaxies. Each image is about 100 arc seconds across. Image: PS1SC.

The closer a star is to us, the larger its angle of parallax will be. Astronomers have defined a standard unit of distance to be the parsec (pc). One parsec is the distance to a point in space that subtends a parallax angle of one arc second. This produces the simple but effective relationship: ...

is should be visible in moderate or larger size telescopes near the border of the constellations Lepus and Columba. It will be a little easier to see in the southern hemisphere, where it will have an apparent movement of 50 arc seconds per minute, ...

A parsec is the length of the long leg of a right triangle, whose short leg is one astronomical unit when the angle between the Sun and the Earth, as seen from an object in space (a star for example), is one arcsecond The word parsec stands for "parallax of one arc second" One kiloparsec (kpc), ...

Also, they are always within 11 arc seconds, or about 1/350 of a degree away from one another. Look for Sirius (it shouldn't be too hard) in the south/south west skies early in the evening. It will be the brightest object in the area.

A feature in the photosphere, 1 to 3 arc seconds in extent, usually not much darker than the dark spaces between photospheric granules. It is distinguished from a sun spot by its short lifetime, 10 to 100 minutes. post-flare loops.

Measured in arc seconds per year.
A positively charged atomic particle contained in the nucleus of an atom. The nucleus of hydrogen atom.
Proton-Proton Chain
A series of three nuclear reactions that build a helium atom by adding together protons. The main energy source in our sun.

See also: See also: Astro, Earth, Star, Sun, Astronomer

Astronomy  Arc minutes  Archeoastronomy

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