Fundamental observations made at Breslau in 1922-1925

1978 ◽  
Vol 48 ◽  
pp. 433-435
Author(s):  
F. Schmeidler
Keyword(s):  
The Sun ◽  
Vertical Circle ◽  
Right Ascension

Meridian observations of fundamental stars were made at Breslau Observatory in 1922 to 1925. The observations in right ascension were made by W.Rabe with the 6-inch transit instrument, whereas the declinations were observed by A.Wilkens with the vertical circle. In both coordinates, observations of the Sun were also made.

scholarly journals XXVIII. On the discordances between the sun's observed and computed right ascensions, as determined at the Blackman-street observatory, in the years 1821 and 1822; with experiments to show that they did not originate in instrumental derangement. also a description of the seven-feet transit with which the observations were procured, and upon which the experiments were made

1826 ◽  
Vol 116 ◽  
pp. 423-483 ◽  
Keyword(s):  
Royal Society ◽  
The Sun ◽  
Accurate Knowledge ◽  
The Subject ◽  
Right Ascension ◽  
Solar Rays

In presenting to the Royal Society the following pages, I am well aware that some apology is necessary; the subject however to which they refer being intimately connected with the progress of astronomy, I am induced to hope that the Society will still receive with indulgence, what would long since have been communicated to them, had other astronomical pursuits allowed me the opportunity. That the sun's right ascension, found by observation , frequently disagrees with that afforded by calculation , astronomers I believe now generally admit; an opinion however has been as generally entertained, that the discordances were the results of instrumental inaccuracy, occasioned by the effects of the solar rays upon certain parts of the instrument; hence observations of the sun have fallen into disrepute, whenever an accurate knowledge of the time is the object of research.

scholarly journals IV.On a supposed alteration in the amount of astronomical aberration of light, produced by the passage of the light through a considerable thickness of refracting medium

1872 ◽  
Vol 20 (130-138) ◽  
pp. 35-39 ◽  
Keyword(s):  
Royal Academy ◽  
Angular Displacement ◽  
Focal Length ◽  
The Sun ◽  
Change Of Direction ◽  
The Subject ◽  
The Difference ◽  
North Polar ◽  
Academy Of Sciences ◽  
Right Ascension

A discussion has taken place on the Continent, conducted partly in the 'Astronomische Nachrichten,’ partly in independent pamphlets, on the change of direction which a ray of light will receive (as inferred from the Undulatory Theory of Light) when it traverses a refracting medium which has a motion of translation. The subject to which attention is particularly called is the effect that will be produced on the apparent amount of that angular displacement of a star or planet which is caused by the Earth’s motion of translation, and is known as the Aberration of Light. It has been conceived that there may be a difference in the amounts of this displacement, as seen with different telescopes, depending on the difference in the thicknesses of their object-glasses. The most important of the papers containing this discussion are:—that of Professor Klinkerfues, contained in a pamphlet published at Leipzig in 1867, August; and those of M. Hoek, one published 1867, October, in No. 1669 of the 'Astronomische Nachrichten,’ and the other published in 1869 in a communication to the Netherlands Royal Academy of Sciences. Professor Klinkerfues maintained that, as a necessary result of the Undulatory Theory, the amount of Aberration would be increased, in accordance with a formula which he has given; and he supported it by the following experiment:— In the telescope of a transit-instrument, whose focal length was about 18 inches, was inserted a column of water 8 inches in length, carried in a tube whose ends were closed with glass plates; and with this instrument he observed the transit of the Sun, and the transits of certain stars whose north-polar distances were nearly the same as that of the Sun, and which passed the meridian nearly at midnight. In these relative positions, the difference between the Apparent Right Ascension of the Sun and those of the stars is affected by double the coefficient of Aberration; and the merely astronomical circumstances are extremely favourable for the accurate testing of the theory. Professor Klinkerfues had computed that the effect of the 8-inch column of water and of a prism in the interior of the telescope would be to increase the coefficient of Aberration by eight seconds of arc. The observation appeared to show that the Aberration was really increased by 7'' 1. It does not appear that this observation was repeated.

The New Abridged Nautical Almanac

1951 ◽  
Vol 4 (04) ◽  
pp. 377-385
Keyword(s):  
Present Form ◽  
Transitional Period ◽  
The Sun ◽  
American Spanish ◽  
Detailed Work ◽  
Right Ascension ◽  
Nautical Almanac

TheAbridged Nautical Almanacin its revised form, for the year 1952, has now appeared. In place of right ascension and the familiar quantitiesEandRwhich were adopted in 1929, it tabulates Greenwich hour angle in arc for the Sun, Moon, planets and Aries, and sidereal hour angle (or versed ascension) for the stars.Greenwich hourangle has been used in air almanacs for a number of years, and several surface almanacs have tabulated it as an alternative to right ascension; it is only recently, however, that it has been given exclusively in surface almanacs. Among the surface almanacs which tabulate G.H.A. at present are the American, Spanish, Argentine, Brazilian and Yugoslav.The redesign of theAbridged Nautical Almanachas been under consideration for many years, but the change was delayed first by the war, and then by the desire to avoid a transitional period during which the new G.H.A. andEandRwere given together; it was also decided to give as much notice of the proposed changes to users as possible. The design in substantially its present form was in fact accomplished in 1947, though the arrangement of the daily pages and much detailed work was carried out later.

scholarly journals XXXVI. Account of a new instrument for measuring small angles, called the prismatic micrometer.

1777 ◽  
Vol 67 ◽  
pp. 799-815
Keyword(s):  
The Sun ◽  
New Instrument ◽  
The Wire ◽  
Right Ascension

Practical astronomy was much benefited by the invention of the wire micrometer, for measuring differences of right ascension and declination: not did it receive less advantage from Mr. Savery's most ingenious invention of the divided object-glass micrometer, which has been rendered more commodious by the late Mr. John Dollond's application of it to the object-end of an achromatic refracting one. But, valuable as the object-glass micrometer undoubtedly is, some difficulties have been found in the use of it, owing to the alteration in the focus of the eye, which are apt to cause it to give different measure of the same angle at different times. For instance, in measuring the Sun's diameter, the axes of the pencils of rays, which come through the two segments of the object-glass from contrary limbs of the Sun, crossing one another at the focus of the telescope under an angle equal to that of the Sun's diameter, the union of the limbs of the two images of the Sun cannot appear perfect unless the eye be disposed to see objects distinctly which are placed at point of interjection.

scholarly journals Measurements of annual parallaxes and proper motions of the red supergiant S Per

2007 ◽  
Vol 3 (S242) ◽  
pp. 378-380 ◽  
Author(s):  
Yoshiharu Asaki ◽  
Shuji Deguchi ◽  
Hirishi Imai ◽  
Kazuya Hachisuka ◽  
Makoto Miyoshi ◽  
...  
Keyword(s):  
Water Vapor ◽  
Proper Motion ◽  
Galactic Center ◽  
Rotation Velocity ◽  
Galactic Rotation ◽  
The Sun ◽  
Proper Motions ◽  
Right Ascension

AbstractVLBI phase-referencing monitoring of water vapor masers around the red supergiant, S Per, was conducted over four years. We successfully obtained proper motions and an annual parallax of the masers and determined the distance to S Per of 2.51±0.09 kpc. The proper motion of the star itself was inferred from the maser proper motions, and it was −0.38 and −1.54 mas/yr for right ascension and declination, respectively. Assuming the distance from the sun to the Galactic center, R0, of 8.5 kpc and the rotation velocity around the sun, Θ0, of 220 km/s, the Galactic rotation velocity around S Per is 200 km/s.

scholarly journals Remarks on a correction of the solar tables required by Mr. South’s observations

1833 ◽  
Vol 2 ◽  
pp. 305-305
Keyword(s):  
The Sun ◽  
Peculiar Form ◽  
The Mean ◽  
Right Ascension ◽  
Nautical Almanac

The discordancies observed by Mr. South between the sun’s right ascension, as deduced from observation, and those given in the Nautical Almanac, follow a law so simple as not to allow of their being regarded as errors of observation, or arising from any casual cause, but justify us in attributing them to imperfections in the solar tables, with the exception of three days, in which there seems to be some ground to suspect error of computation. A single inspection of these discrepancies, Mr. Airy observes, suffices to show that they arise almost entirely from an error in the epoch, and an error in the place of the perigee. From the peculiar form of the tables in Vince’s Astronomy, which give great facility to the introduction of an error in the excentricity, he was induced at first to suspect that one might exist; but on calculation found the error in the equation of the centre so small as to be entirely insensible. He then proceeds to detail the process by which, from Mr. South’s observations, he has deduced the amount of the several errors, which consist in regarding the epoch, the mean anomaly, and the equation of the centre, as erroneous by three very small unknown quantities, and forming as many equations of condition for determining them as there are observations. These combined and resolved, so as to give the most probable result, lead to the conclusions, first, that the correction of the equation of the centre is evanescent; secondly, that the epochs of the sun must all be increased by 9", and the epochs of the perigee each by 1' 48".

Long-term evaluation of orbital dynamics in the Sun-planet system considering axial-tilt

2018 ◽  
Vol 33 (15) ◽  
pp. 1850083 ◽  
Author(s):  
Majid Bakhtiari ◽  
Kamran Daneshjou
Keyword(s):  
Three Dimensional ◽  
Point Of View ◽  
Dynamic Equations ◽  
The Sun ◽  
Proposed Model ◽  
Term Evaluation ◽  
Short Time ◽  
Right Ascension ◽  
Axial Tilt

In this paper, the axial-tilt (obliquity) effect of planets on the motion of planets’ orbiter in prolonged space missions has been investigated in the presence of the Sun gravity. The proposed model is based on non-simplified perturbed dynamic equations of planetary orbiter motion. From a new point of view, in this work, the dynamic equations regarding a disturbing body in elliptic inclined three-dimensional orbit are derived. The accuracy of this non-simplified method is validated with dual-averaged method employed on a generalized Earth–Moon system. It is shown that the neglected short-time oscillations in dual-averaged technique can accumulate and propel to remarkable errors in the prolonged evolution. After validation, the effects of the planet’s axial-tilt on eccentricity, inclination and right ascension of the ascending node of the orbiter are investigated. Moreover, a generalized model is provided to study the effects of third-body inclination and eccentricity on orbit characteristics. It is shown that the planet’s axial-tilt is the key to facilitating some significant changes in orbital elements in long-term mission and short-time oscillations must be considered in accurate prolonged evaluation.

scholarly journals A Precise Algorithm for Computing Sun Position on a Satellite

2019 ◽  
Author(s):  
Tao Zheng ◽  
Fei Zheng ◽  
Xi Rui ◽  
Xiang Ji
Keyword(s):  
Coordinate System ◽  
High Precision ◽  
Pitch Angle ◽  
Azimuth Angle ◽  
Maximum Deviation ◽  
The Sun ◽  
Solar Concentrator ◽  
The Difference ◽  
The One ◽  
Right Ascension

To meet the high precision sun tracking needs of a space deployable membrane solar concentrator and other equipment, an existing algorithm for accurately computing the sun position is improved. Firstly, compared with other theories, the VSOP (variation seculaires des orbits planetaires) 87 theory is selected and adopted to obtain the sun position in the second equatorial coordinate system. Comparing the results with data of the astronomical almanac from 2015, it is found that the deviation of the apparent right ascension does not exceed 0.17 arc seconds, while that of the apparent declination does not exceed 1.2 arc seconds. Then, to eliminate the difference in the direction of the sun position with respect to the satellite caused by the size of the satellite’s orbit, a translation transform is introduced in the proposed algorithm. Finally, the proposed algorithm is applied to the orbit of the satellite designated by SJ-4 (shijian-4). Under the condition that both of the existing and improved algorithms adopt the VSOP87 theory to compute sun position in the second equatorial coordinate system, the maximum deviation of the azimuth angle on the SJ-4 is 35.19 arc seconds and the one of pitch angle is 19.93 arc seconds, when the deviation is computed by subtracting the results given by both algorithms. In summary, the proposed algorithm is more accurate than the existing one.

scholarly journals I. Some particulars of the transit of Venus across the Sun, 1874, Dec. 9, observed on the Himalaya Mountains, Mussoorie, at Mary Villa.—Note II

1875 ◽  
Vol 23 (156-163) ◽  
pp. 378-384 ◽  
Keyword(s):  
The Sun ◽  
Vertical Circle ◽  
The Himalaya ◽  
Himalaya Mountains

1. The instruments used were the following:— An altazimuth by Troughton and Simms, with an azimuth circle of 8 inches diameter read by three verniers, and a complete vertical circle, also of 8 inches, read by two verniers. The circles are divided to every 10' of arc, and the verniers afford readings to 10", or by estimation to at least 5". The instrument is well provided with spirit-levels surmounted by scales. The altazimuth was used for fixing the station of observation and for determining time. A mountain barometer. A thermometer.

scholarly journals VI. Directions for using the common micrometer, taken from a paper in the late Dr. Bradley's hand-writing; communicated by Nevil Maskelyne, Astronomer Royal, and F. R. S

1772 ◽  
Vol 62 ◽  
pp. 46-53 ◽  
Keyword(s):  
The Sun ◽  
The Common ◽  
The Difference ◽  
Pass Through ◽  
Nevil Maskelyne ◽  
Hand Writing ◽  
Right Ascension

Micrometers, as first contrived, being only adapted to the measuring small angles, as the diameters of the Sun and Moon, or other planets, and taking the distance of such objects as appeared within the aperture of the telescope at the same time, were not of so general use as those which are contrived not only to answer the ends that the first inventers aimed at, but likewise, to take the difference of right ascension and declination of such objects as are farther asunder than the telescope will take in at once, but which pass through the aperture of it at different times.

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