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42-632: The observatory produced the popular sky atlas Skalnate Pleso Atlas of the Heavens by Antonín Bečvář , who founded the observatory in 1943. It is also known for its visual comet hunting and for its astrometric observations and discoveries of minor planets . The asteroid 2619 Skalnaté Pleso was named in honor of the observatory. Noted astronomers who worked at the observatory include Milan Antal , Antonín Mrkos , Ľudmila Pajdušáková and Margita Kresáková (née Vozárová), as well as Alois Paroubek and Regina Podstanická . Discoveries include

84-690: A luxurious, full-color version to a black-and-white version of size 23 in × 15 in (58 cm × 38 cm). Pursuant to Bečvář's request, royalties were used to purchase special astronomical photographic plates for the Skalnaté Observatory. Bečvář went on to create a number of other atlases: Atlas Eclipticalis (the celestial region between −30° and +30° declination on 32 maps), Atlas Borealis (the celestial region north of declination +30° on 24 maps), and Atlas Australis (the celestial region south of declination −30° on 24 maps). Stellar clusters and nebulae are not plotted, but

126-688: A number of existing catalogs, including the Henry Draper catalog , the Aitken New General Catalog of Double Stars , and the Boss General Catalog . About ten photographic atlases were used as well. To plot each of the objects, one of 20 stencil patterns was selected and positioned. It was also necessary to compute the shift in the apparent position of each of the objects to epoch 1950.0. About 3,000 man-hours of work were involved. Immediately after publication of

168-499: A particular equinox, that is, the equinox of a particular date, known as an epoch ; the coordinates are referred to the direction of the equinox at that date. For instance, the Astronomical Almanac lists the heliocentric position of Mars at 0h Terrestrial Time , 4 January 2010 as: longitude 118°09′15.8″, latitude +1°43′16.7″, true heliocentric distance 1.6302454 AU, mean equinox and ecliptic of date. This specifies

210-566: A period of about 26,000 years, a process known as lunisolar precession , as it is due mostly to the gravitational effect of the Moon and Sun on Earth's equatorial bulge . Likewise, the ecliptic itself is not fixed. The gravitational perturbations of the other bodies of the Solar System cause a much smaller motion of the plane of Earth's orbit, and hence of the ecliptic, known as planetary precession . The combined action of these two motions

252-429: A periodic component to the position of the equinoxes; the positions of the celestial equator and (March) equinox with fully updated precession and nutation are called the true equator and equinox ; the positions without nutation are the mean equator and equinox . Obliquity of the ecliptic is the term used by astronomers for the inclination of Earth's equator with respect to the ecliptic, or of Earth's rotation axis to

294-403: A perpendicular to the ecliptic. It is about 23.4° and is currently decreasing 0.013 degrees (47 arcseconds) per hundred years because of planetary perturbations. The angular value of the obliquity is found by observation of the motions of Earth and other planets over many years. Astronomers produce new fundamental ephemerides as the accuracy of observation improves and as the understanding of

336-460: A six-color press was used to distinguish six basic spectral classes of stars. These atlases were especially helpful in the early days of position measurements of artificial satellites. Ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth around the Sun . From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of

378-578: A total of 32,571. The stellar magnitudes are indicated by circles with graded sizes. Double and multiple stars are identified and visual binaries are differentiated from spectroscopic binaries . All known variable stars are identified, including novae that had maxima brighter than magnitude 7.75 (totalling 443). 249 star clusters are shown and their relative size indicated. All known globular clusters are shown. 1,130 extragalactic systems are included as are many Galactic objects including planetary nebulae . Bright and dark diffuse nebulae are shown, and

420-450: A year traces out a path along the ecliptic against the background of stars . The ecliptic is an important reference plane and is the basis of the ecliptic coordinate system . The ecliptic is the apparent path of the Sun throughout the course of a year . Because Earth takes one year to orbit the Sun, the apparent position of the Sun takes one year to make a complete circuit of the ecliptic. With slightly more than 365 days in one year,

462-432: Is a simplification, based on a hypothetical Earth that orbits at uniform speed around the Sun. The actual speed with which Earth orbits the Sun varies slightly during the year, so the speed with which the Sun seems to move along the ecliptic also varies. For example, the Sun is north of the celestial equator for about 185 days of each year, and south of it for about 180 days. The variation of orbital speed accounts for part of

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504-478: Is also used occasionally; the x -axis is directed toward the March equinox, the y -axis 90° to the east, and the z -axis toward the north ecliptic pole; the astronomical unit is the unit of measure. Symbols for ecliptic coordinates are somewhat standardized; see the table. Ecliptic coordinates are convenient for specifying positions of Solar System objects, as most of the planets' orbits have small inclinations to

546-457: Is called general precession , and changes the position of the equinoxes by about 50 arc seconds (about 0.014°) per year. Once again, this is a simplification. Periodic motions of the Moon and apparent periodic motions of the Sun (actually of Earth in its orbit) cause short-term small-amplitude periodic oscillations of Earth's axis, and hence the celestial equator, known as nutation . This adds

588-490: Is divided into 12 signs of 30° longitude, each of which approximates the Sun's motion in one month. In ancient times, the signs corresponded roughly to 12 of the constellations that straddle the ecliptic. These signs are sometimes still used in modern terminology. The " First Point of Aries " was named when the March equinox Sun was actually in the constellation Aries ; it has since moved into Pisces because of precession of

630-928: Is named after the Skalnaté Pleso Observatory in Slovakia where it was produced. The first versions were published by the Czechoslovak Astronomical Society in 1948; later that year, Sky Publishing Corporation acquired the copyright and began publication in the United States. The charts were hand-drawn by Antonín Bečvář . At the time it was first published, the Atlas Coeli was unique in that it contained essentially all non-stellar objects (star clusters, galaxies etc.) that were visible in an 8-inch telescope, in addition to stars brighter than magnitude 7.75. Until

672-534: Is near an ascending or descending node at the same time it is at conjunction ( new ) or opposition ( full ). The ecliptic is so named because the ancients noted that eclipses only occur when the Moon is crossing it. The exact instants of equinoxes and solstices are the times when the apparent ecliptic longitude (including the effects of aberration and nutation ) of the Sun is 0°, 90°, 180°, and 270°. Because of perturbations of Earth's orbit and anomalies of

714-428: Is not coplanar with the ecliptic plane, but is inclined to it by an angle of about 23.4°, which is known as the obliquity of the ecliptic . If the equator is projected outward to the celestial sphere , forming the celestial equator , it crosses the ecliptic at two points known as the equinoxes . The Sun, in its apparent motion along the ecliptic, crosses the celestial equator at these points, one from south to north,

756-722: The Atlas Coeli , a supplement was produced called the Atlas Coeli II - Katalog 1950.0 . The Catalogue contains data and descriptions of approximately 12000 objects plotted in the Atlas . All stars to magnitude 6.25 are included as well as a large number of the non-stellar objects. Stellar data includes the 1950.0 coordinates with their annual variations; proper motion ; apparent magnitude (Revised Harvard Photometric [RHP, or HR] system); absolute magnitude ; spectral type (Mt. Wilson scheme); parallax ; radial velocity; standard name of star and its constellation; and notes indicating if

798-405: The dynamics increases, and from these ephemerides various astronomical values, including the obliquity, are derived. Until 1983 the obliquity for any date was calculated from work of Newcomb , who analyzed positions of the planets until about 1895: ε = 23°27′08.26″ − 46.845″ T − 0.0059″ T + 0.00181″ T where ε is the obliquity and T is tropical centuries from B1900.0 to

840-575: The equation of time . Because of the movement of Earth around the Earth–Moon center of mass , the apparent path of the Sun wobbles slightly, with a period of about one month . Because of further perturbations by the other planets of the Solar System , the Earth–Moon barycenter wobbles slightly around a mean position in a complex fashion. Because Earth's rotational axis is not perpendicular to its orbital plane , Earth's equatorial plane

882-407: The mean equinox of 4 January 2010 0h TT as above , without the addition of nutation. Because the orbit of the Moon is inclined only about 5.145° to the ecliptic and the Sun is always very near the ecliptic, eclipses always occur on or near it. Because of the inclination of the Moon's orbit, eclipses do not occur at every conjunction and opposition of the Sun and Moon, but only when the Moon

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924-533: The IAU had accepted Achird, Hassaleh, Hatysa, Heze, Kraz, Sarin and Segin as official names for those stars. A six-color improved version of the Atlas was published by the Czechoslovak Academy of Sciences in 1956. The copyright to publish the Atlas outside of Czechoslovakia was purchased by Sky Publishing Corporation in 1949. Under this copyright, the Atlas was published in a series of editions, from

966-421: The Solar System orbit the Sun in nearly the same plane. This is likely due to the way in which the Solar System formed from a protoplanetary disk . Probably the closest current representation of the disk is known as the invariable plane of the Solar System . Earth's orbit, and hence, the ecliptic, is inclined a little more than 1° to the invariable plane, Jupiter's orbit is within a little more than ½° of it, and

1008-418: The Sun moves a little less than 1° eastward every day. This small difference in the Sun's position against the stars causes any particular spot on Earth's surface to catch up with (and stand directly north or south of) the Sun about four minutes later each day than it would if Earth did not orbit; a day on Earth is therefore 24 hours long rather than the approximately 23-hour 56-minute sidereal day . Again, this

1050-402: The actual outlines of those larger than 10' in diameter are painstakingly drawn. The Milky Way and prominent obscuring clouds within it are indicated by isophotic lines. Constellation boundaries are clearly but unobtrusively drawn. The celestial equator and ecliptic are indicated. The brightest radio sources are also shown. The Atlas Coeli is famous for its clean appearance and for

1092-461: The calendar , the dates of these are not fixed. The ecliptic currently passes through the following thirteen constellations : There are twelve constellations that are not on the ecliptic, but are close enough that the Moon and planets can occasionally appear in them. The ecliptic forms the center of the zodiac , a celestial belt about 20° wide in latitude through which the Sun, Moon, and planets always appear to move. Traditionally, this region

1134-410: The celestial equator. Spherical coordinates , known as ecliptic longitude and latitude or celestial longitude and latitude, are used to specify positions of bodies on the celestial sphere with respect to the ecliptic. Longitude is measured positively eastward 0° to 360° along the ecliptic from the March equinox, the same direction in which the Sun appears to move. Latitude is measured perpendicular to

1176-729: The date in question. From 1984, the Jet Propulsion Laboratory's DE series of computer-generated ephemerides took over as the fundamental ephemeris of the Astronomical Almanac . Obliquity based on DE200, which analyzed observations from 1911 to 1979, was calculated: ε = 23°26′21.45″ − 46.815″ T − 0.0006″ T + 0.00181″ T where hereafter T is Julian centuries from J2000.0 . JPL's fundamental ephemerides have been continually updated. The Astronomical Almanac for 2010 specifies: ε = 23°26′21.406″ − 46.836769″ T − 0.0001831″ T + 0.00200340″ T − 0.576×10 ″ T − 4.34×10 ″ T These expressions for

1218-412: The ecliptic, and therefore always appear relatively close to it on the sky. Because Earth's orbit, and hence the ecliptic, moves very little, it is a relatively fixed reference with respect to the stars. Because of the precessional motion of the equinox , the ecliptic coordinates of objects on the celestial sphere are continuously changing. Specifying a position in ecliptic coordinates requires specifying

1260-436: The ecliptic, to +90° northward or −90° southward to the poles of the ecliptic, the ecliptic itself being 0° latitude. For a complete spherical position, a distance parameter is also necessary. Different distance units are used for different objects. Within the Solar System, astronomical units are used, and for objects near Earth , Earth radii or kilometers are used. A corresponding right-handed rectangular coordinate system

1302-831: The literature. These 14 stars are: The two that may have explanations are "Segin" (ε Cas), possibly a written variant of "Seginus" (γ Boo), and "Haris", possibly a derivation from ħāris al-shamāl "Guardian of the North", the Arabic name of Bootes or Arcturus . For the others, there is no apparent explanation in Latin, Greek or Arabic. Kunitzsch spent fifteen years trying to trace the origins of these names in earlier sources and by contacting Czechoslovak astronomers who might know of former collaborators of Bečvář's, but without success. Amateur astronomers German Hans Vehrenberg and English Patrick Moore follow these names. As of early 2019,

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1344-424: The mid-1970s when it went out of print, the Atlas was extremely popular among amateur astronomers, especially those engaged in comet hunting and the study of variable stars . The Atlas Coeli was also widely used by professional astronomers. Many astronomical observatories still contain copies. The Atlas Coeli covers both hemispheres with 16 charts. The coordinate system is referred to equinox 1950.0 and

1386-487: The minor planets 1807 Slovakia and 1989 Tatry . This article about a specific observatory, telescope or astronomical instrument is a stub . You can help Misplaced Pages by expanding it . Skalnate Pleso Atlas of the Heavens The Skalnaté Pleso Atlas of the Heavens ( Atlas Coeli Skalnaté Pleso 1950.0 ) is a set of 16 celestial charts covering the entire sky. It

1428-408: The obliquity are intended for high precision over a relatively short time span, perhaps several centuries. J. Laskar computed an expression to order T good to 0.04″ /1000 years over 10,000 years. All of these expressions are for the mean obliquity, that is, without the nutation of the equator included. The true or instantaneous obliquity includes the nutation. Most of the major bodies of

1470-468: The other from north to south. The crossing from south to north is known as the March equinox , also known as the first point of Aries and the ascending node of the ecliptic on the celestial equator. The crossing from north to south is the September equinox or descending node . The orientation of Earth's axis and equator are not fixed in space, but rotate about the poles of the ecliptic with

1512-457: The other major planets are all within about 6°. Because of this, most Solar System bodies appear very close to the ecliptic in the sky. The invariable plane is defined by the angular momentum of the entire Solar System, essentially the vector sum of all of the orbital and rotational angular momenta of all the bodies of the system; more than 60% of the total comes from the orbit of Jupiter. That sum requires precise knowledge of every object in

1554-445: The scale is 1° = 0.75 cm. There are six charts of the equatorial regions on a rectangular graticule, covering declinations from +25° to -25°; four charts for each hemisphere with straight, converging hour circles and concentric, equally-spaced declination circles covering declinations 20° - 65°; and, for each hemisphere, a circumpolar chart covering declination 65° to the pole. All stars brighter than 7.75 magnitude are included, for

1596-468: The sky's distant background. The ecliptic forms one of the two fundamental planes used as reference for positions on the celestial sphere, the other being the celestial equator . Perpendicular to the ecliptic are the ecliptic poles , the north ecliptic pole being the pole north of the equator. Of the two fundamental planes, the ecliptic is closer to unmoving against the background stars, its motion due to planetary precession being roughly 1/100 that of

1638-402: The star is double or variable. The Catalogue includes a number of other tables with data on double and multiple stars, galactic and extragalactic nebulae, and radio sources. Paul Kunitzsch found 14 proper names of stars that are first attested in the catalogue, and for which he was unable to find any clues as to their origin. For two more he suggested etymologies, but without antecedents in

1680-460: The system, making it a somewhat uncertain value. Because of the uncertainty regarding the exact location of the invariable plane, and because the ecliptic is well defined by the apparent motion of the Sun, the ecliptic is used as the reference plane of the Solar System both for precision and convenience. The only drawback of using the ecliptic instead of the invariable plane is that over geologic time scales, it will move against fixed reference points in

1722-400: The wealth of data it contains. The drawing is beautifully and precisely done and the printing is excellent. Many other star charts have been strongly influenced by the style of the Atlas Coeli . For instance, the popular Sky Atlas 2000.0 of Wil Tirion adopted the symbols for various types of objects, the division of scales, and the script directly from the Atlas Coeli . The Atlas Coeli

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1764-632: Was created in the period 1947-1948 at the Skalnaté Pleso Observatory in Slovakia (then Czechoslovakia) under the direction of Antonín Bečvář, based on an idea of Czechoslovakian amateur astronomer Josef Klepešta. Much of the work was carried out by a volunteer group of students at the Observatory; the final plotting of the Atlas , which was entirely hand-drawn, was the work of Bečvář. Positional and magnitude data were taken from

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