The Time of Day
... round, the Sun can’t be “overhead” everywhere at the same time, so it can’t be noon everywhere at the same time. By the late 1800s, with the increasing speed of travel and communications, it became confusing for each city to maintain its own time according to the position of the Sun in the sky. By i ...
... round, the Sun can’t be “overhead” everywhere at the same time, so it can’t be noon everywhere at the same time. By the late 1800s, with the increasing speed of travel and communications, it became confusing for each city to maintain its own time according to the position of the Sun in the sky. By i ...
SylTerNav\4Curr\emet
... define the apparent solar day and state the relationship between local hour angle (LHA) of the sun and the latitude; define the sidereal day and explain why it is a fixed time interval; explain the reasons for the sun's irregular rate of change of sidereal hour angle (SHA) and hence the necessity to ...
... define the apparent solar day and state the relationship between local hour angle (LHA) of the sun and the latitude; define the sidereal day and explain why it is a fixed time interval; explain the reasons for the sun's irregular rate of change of sidereal hour angle (SHA) and hence the necessity to ...
(Preprint) AAS 11-665 - Long Now > Media > Uploader
... Earth’s axis. Orrery Time is intended to approximate the solar system barycentric coordinate time. In that sense it is similar in purpose to Barycentric Dynamical Time (TDB), or the older Ephemeris Time (ET). Orrery Time differs from Corrected Solar Time because the rate of the Earth’s rotation is s ...
... Earth’s axis. Orrery Time is intended to approximate the solar system barycentric coordinate time. In that sense it is similar in purpose to Barycentric Dynamical Time (TDB), or the older Ephemeris Time (ET). Orrery Time differs from Corrected Solar Time because the rate of the Earth’s rotation is s ...
ASTRONOMICAL REFERENCE SYSTEMS AND FRAMES
... P Therefore, it is reasonable to select an origin that would be independent of the Earth’s orbital motion and of the adopted model of precession-nutation. The advantage is also to define an angle having a relatively simple relation to Universal time (UT1), whose definition should not change each tim ...
... P Therefore, it is reasonable to select an origin that would be independent of the Earth’s orbital motion and of the adopted model of precession-nutation. The advantage is also to define an angle having a relatively simple relation to Universal time (UT1), whose definition should not change each tim ...
Phase: Period Normalization
... parabola which then presumably left us with only the 3rd body light-time effects. A non-linear least squares search was then used on these residuals to arrive at the best fit orbital elements. After determining the best fit to these residuals, the light-time corrections were subtracted, leaving us s ...
... parabola which then presumably left us with only the 3rd body light-time effects. A non-linear least squares search was then used on these residuals to arrive at the best fit orbital elements. After determining the best fit to these residuals, the light-time corrections were subtracted, leaving us s ...
Celestial Coordinates Celestial Sphere: The celestial sphere is an
... meridian. The sidereal day is 23 hours, 56 minutes, and 4.1 seconds long. Sidereal Time: Official sidereal time is the day beginning at the hour angle of the vernal equinox. Star positions are given using this sidereal time. The position of a star with respect to the oberver's meridian is then relat ...
... meridian. The sidereal day is 23 hours, 56 minutes, and 4.1 seconds long. Sidereal Time: Official sidereal time is the day beginning at the hour angle of the vernal equinox. Star positions are given using this sidereal time. The position of a star with respect to the oberver's meridian is then relat ...
arXiv:0905.3008v1 [astro-ph.EP] 19 May 2009
... In this paper, we considered the secular increase of astronomical unit recently reported by Krasinsky and Brumberg (2004), and suggested a possible explanation for this secular trend by means of the conservation law of total angular momentum. Assuming the existence of some tidal interactions that tr ...
... In this paper, we considered the secular increase of astronomical unit recently reported by Krasinsky and Brumberg (2004), and suggested a possible explanation for this secular trend by means of the conservation law of total angular momentum. Assuming the existence of some tidal interactions that tr ...
Basics – II. Time, Magnitudes and Spectral types
... This concept was already known to the Egyptians and it was an Alexandrian scholar, Sosigenes, who advised Julius Caesar to introduce a similar calendar into the Roman empire in 46 B.C. The Julian calendar had every fourth year a leap year. (Incidentally, Julius Caesar ordered that 46 BC should have ...
... This concept was already known to the Egyptians and it was an Alexandrian scholar, Sosigenes, who advised Julius Caesar to introduce a similar calendar into the Roman empire in 46 B.C. The Julian calendar had every fourth year a leap year. (Incidentally, Julius Caesar ordered that 46 BC should have ...
What, and Why, is the International Astronomical Union?
... to cover the sky. Most of them were eventually taken, but, 35 years after the project began, only four of the 20 zones had been completely measured, printed, and distributed (those of Greenwich, Oxford, Perth, and the zone Hyderabad had originally agreed to do, they took on another later). The Carte ...
... to cover the sky. Most of them were eventually taken, but, 35 years after the project began, only four of the 20 zones had been completely measured, printed, and distributed (those of Greenwich, Oxford, Perth, and the zone Hyderabad had originally agreed to do, they took on another later). The Carte ...
The standard error of the mean for pointings would be
... standard deviations, what standard error values should be used as the project options instrument default settings? First of all, the term "standard error" is short for "standard error of the mean." It is an estimate of the uncertainty of the mean (or average) of a set of field observations. The equa ...
... standard deviations, what standard error values should be used as the project options instrument default settings? First of all, the term "standard error" is short for "standard error of the mean." It is an estimate of the uncertainty of the mean (or average) of a set of field observations. The equa ...
It`s about Time - Jodrell Bank Centre for Astrophysics
... The most accurate atomic clock in continuous use today is NIST-F1, which is now the USA’s primary time and frequency standard. It is a caesium fountain atomic clock which extracts the resonant frequency (9,192,631,770 Hz) of the caesium atoms when they are virtually stationary. Six infrared laser b ...
... The most accurate atomic clock in continuous use today is NIST-F1, which is now the USA’s primary time and frequency standard. It is a caesium fountain atomic clock which extracts the resonant frequency (9,192,631,770 Hz) of the caesium atoms when they are virtually stationary. Six infrared laser b ...
Coordinates and Time - University of Florida Astronomy
... Terresterial Dynamical Time (TDT) and International Atomic Time (IAT) The modern standard time is based upon the SI second, which is defined in terms of the oscillations for a particular transition of 133Cs rather than astronomical measures. One second = 9192631770 oscillations. IAT is effectively t ...
... Terresterial Dynamical Time (TDT) and International Atomic Time (IAT) The modern standard time is based upon the SI second, which is defined in terms of the oscillations for a particular transition of 133Cs rather than astronomical measures. One second = 9192631770 oscillations. IAT is effectively t ...
The Geographic Position of a Celestial Body
... Interactive Computer Ephemeris, ICE, is a computer almanac developed by the U.S. Naval Observatory (successor of the Floppy Almanac). ICE is FREEWARE (no longer supported by USNO), compact, easy to use, and provides a vast quantity of accurate astronomical data for a time span of almost 250 (!) year ...
... Interactive Computer Ephemeris, ICE, is a computer almanac developed by the U.S. Naval Observatory (successor of the Floppy Almanac). ICE is FREEWARE (no longer supported by USNO), compact, easy to use, and provides a vast quantity of accurate astronomical data for a time span of almost 250 (!) year ...
NATS1311_091108_bw - The University of Texas at Dallas
... Temps Atomique International (TAI) or International Atomic Time weighted average of the time kept by about 200 cesium atomic clocks in over 50 national laboratories worldwide - available since 1955 UT1 - timescale defined by the Earth's rotation - computed by the International Earth Rotation and Ref ...
... Temps Atomique International (TAI) or International Atomic Time weighted average of the time kept by about 200 cesium atomic clocks in over 50 national laboratories worldwide - available since 1955 UT1 - timescale defined by the Earth's rotation - computed by the International Earth Rotation and Ref ...
2 Coordinate systems
... Let X be the position of a star on the celestial sphere. Any great circle drawn through Z is called a vertical circle; in particular, the vertical circle through X is ZXA. In the plane of ZXA, the angle AOX (or the great circle arc AX) is called the altitude denoted by a. Since OZ is perpendicular t ...
... Let X be the position of a star on the celestial sphere. Any great circle drawn through Z is called a vertical circle; in particular, the vertical circle through X is ZXA. In the plane of ZXA, the angle AOX (or the great circle arc AX) is called the altitude denoted by a. Since OZ is perpendicular t ...
Time
... This eliminates three leap years in every four centuries and neatly solves the problem. The result, in the centuries since the reform, is that 1600 and 2000 are normal leap years, but the intervening 1700, 1800 and 1900 do not include February 29. ...
... This eliminates three leap years in every four centuries and neatly solves the problem. The result, in the centuries since the reform, is that 1600 and 2000 are normal leap years, but the intervening 1700, 1800 and 1900 do not include February 29. ...
Secular Increase of the Astronomical Unit: a Possible Explanation in
... investigated this effect of solar mass loss, and concluded that it can only account for less than one tenth of the reported value by Krasinsky and Brumberg. The third term on the left-hand-side of equation (18) is the contribution from a change in the solar radius. Although a very short-time and sma ...
... investigated this effect of solar mass loss, and concluded that it can only account for less than one tenth of the reported value by Krasinsky and Brumberg. The third term on the left-hand-side of equation (18) is the contribution from a change in the solar radius. Although a very short-time and sma ...
Some Concepts of Physics
... Refinement in the Definition of the Unit of Length • In 1983 the meter was redefined again to further reduce uncertainty. The metre was defined in terms of the speed of light and time. It is now the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 of a second. ...
... Refinement in the Definition of the Unit of Length • In 1983 the meter was redefined again to further reduce uncertainty. The metre was defined in terms of the speed of light and time. It is now the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 of a second. ...
AST 443/PHY 517 Homework 1
... Which, if any, are observable (zenith distance <60o )? Which, if any, are above the horizon? 4. Which of these 5 stars can be observed at some time on this night from Cerro Tololo? At what times? 5. Which of these 5 stars is closest to the moon? What is the angular distance? 6. The sidereal time at ...
... Which, if any, are observable (zenith distance <60o )? Which, if any, are above the horizon? 4. Which of these 5 stars can be observed at some time on this night from Cerro Tololo? At what times? 5. Which of these 5 stars is closest to the moon? What is the angular distance? 6. The sidereal time at ...
Moonlight project - Observations of Lunar rotation and Ephemeris by
... lunar ephemeris, lunar rotation and other disturbing factors such as the effect of general relativity. A combination of LLR and the astrometry on the Moon will improve the accuracy of both the lunar ephemeris and the lunar rotation since the parameters are separated well. The moonlight project measu ...
... lunar ephemeris, lunar rotation and other disturbing factors such as the effect of general relativity. A combination of LLR and the astrometry on the Moon will improve the accuracy of both the lunar ephemeris and the lunar rotation since the parameters are separated well. The moonlight project measu ...
MagdaStavinschi_bothtalks
... For a dynamical definition, one has to establish (using the conventional model) a numerical theory of the motion of planets, and the position of reference stars are determined w.r.t. the observed positions of planets. => R.F. is realized by a fundamental star catalogue. The last such catalogue is t ...
... For a dynamical definition, one has to establish (using the conventional model) a numerical theory of the motion of planets, and the position of reference stars are determined w.r.t. the observed positions of planets. => R.F. is realized by a fundamental star catalogue. The last such catalogue is t ...