Norton's Star Atlas

Norton's Star Atlas is a set of 16 celestial charts, first published in 1910 and currently in its 20th edition under the editorship of Ian Ridpath. The Star Atlas covers the entire northern and southern sky, with accompanying reference information for amateur astronomers. The charts used in the first 17 editions of the Atlas were drawn by a British schoolmaster, Arthur Philip Norton (1876–1955), after whom the Atlas was named. Norton intended his star atlas to be used in conjunction with the highly popular observing handbooks written by the British astronomers William Henry Smyth and Thomas William Webb, and consequently most of the objects featured in those guidebooks were marked on the charts. The Atlas also found favour among professional astronomers, earning it the reputation of the most widely used and best-known celestial atlas of its day.

Arrangement and projection

Norton’s Star Atlas became highly popular because of its convenient arrangement of dividing the sky into six vertical slices, or gores, like portions of a globe. Each gore covered 4 hours of right ascension, from declination 60 degrees north to 60 degrees south, drawn on a projection specially designed by Norton. The north and south polar regions of the sky were covered by separate charts on a standard azimuthal equidistant projection, extending from the celestial poles to declination 50 degrees north and south.

Early editions

For the first edition, Norton based his charts on the Uranométrie Générale star catalogue compiled by the Belgian astronomer Jean-Charles Houzeau. Constellation boundaries were represented by dashed lines meandering between the stars, for no official boundaries were then established. For the 5th edition of the Atlas, published in 1933, Norton completely redrew the charts, despite now suffering from severely impaired vision in his left eye due to a blood clot behind the retina. This time he used the Harvard Revised Photometry catalogue for the positions and brightnesses of the stars. In this 5th edition the Milky Way was included for the first time, and he incorporated the official constellation boundaries that had been laid down by the International Astronomical Union in 1930.

Norton redrew his charts yet again for the 9th edition published in 1943, extending the magnitude limit of the stars from 6.2 to 6.35. Positions were now given for the standard epoch of 1950, as against 1920 previously. The 9th edition charts remained in use up to and including the 17th edition of Norton’s Star Atlas published in 1978, long after Norton’s death.

The handbook

In addition to the charts, Norton’s Star Atlas also contained a reference section featuring practical information and data of particular interest to observers. Most of this text was the work of the publisher and various expert contributors. With each passing edition, the text grew into a reference handbook as essential for amateur astronomers as the charts themselves.

Modern era

By the 1980s, Norton’s Star Atlas had come to look dated. In 1989 a totally new edition was published, the 18th, under the title Norton’s 2000.0 to emphasize that its charts had been redrawn to the new standard epoch of 2000. Sadly from then, it is no longer printed on stout paper unlike previous editions. Resulting in the atlas not being very suitable for use on a dew laden night. These charts were computer-plotted by the cartographic company of John Bartholomew and Son Ltd. in Edinburgh, Scotland, taking star positions and brightnesses from the most recent version of the Bright Star Catalogue, the successor to the Harvard Revised Photometry. The total number of stars plotted was over 8800, reaching to magnitude 6.5. The text was extensively rewritten and reorganized under the editorship of the British astronomy writer Ian Ridpath. For the first time in its history, Norton’s Star Atlas contained nothing by Norton himself.

A further break with the past came with the 20th edition in 2003 when publication of the title moved to New York, although the editor and contributors remained in the UK. For this edition the charts were replotted and the reference section heavily revised to reflect the latest advances in amateur astronomy.

External links

Beta Cephei

Beta Cephei (β Cephei, abbreviated Beta Cep, β Cep) is a triple star system of the third magnitude in the constellation of Cepheus. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 690 light-years distant from the Sun. It is the prototype of the Beta Cephei variable stars.

It consists of a binary pair (designated Beta Cephei A) together with a third companion (B). The binary's two components are themselves designated Beta Cephei Aa (also named Alfirk) and Ab.

Camelopardalis

Camelopardalis is a large but faint constellation of the northern sky representing a giraffe. The constellation was introduced in 1612 or 1613 by Petrus Plancius. Some older astronomy books give Camelopardalus or Camelopardus as alternative spellings of the name, but the official version recognized by the International Astronomical Union is Camelopardalis.

Celestial cartography

Celestial cartography, uranography, astrography or star cartography is the fringe of astronomy and branch of cartography concerned with mapping stars, galaxies, and other astronomical objects on the celestial sphere. Measuring the position and light of charted objects requires a variety of instruments and techniques. These techniques have developed from angle measurements with quadrants and the unaided eye, through sextants combined with lenses for light magnification, up to current methods which include computer-automated space telescopes. Uranographers have historically produced planetary position tables, star tables, and star maps for use by both amateur and professional astronomers. More recently computerized star maps have been compiled, and automated positioning of telescopes is accomplished using databases of stars and other astronomical objects.

Constellation

A constellation is a group of stars that forms an imaginary outline or pattern on the celestial sphere, typically representing an animal, mythological person or creature, a god, or an inanimate object.The origins of the earliest constellations likely go back to prehistory. People used them to relate stories of their beliefs, experiences, creation, or mythology. Different cultures and countries adopted their own constellations, some of which lasted into the early 20th century before today's constellations were internationally recognized. Adoption of constellations has changed significantly over time. Many have changed in size or shape. Some became popular, only to drop into obscurity. Others were limited to single cultures or nations.

The 48 traditional Western constellations are Greek. They are given in Aratus' work Phenomena and Ptolemy's Almagest, though their origin probably predates these works by several centuries. Constellations in the far southern sky were added from the 15th century until the mid-18th century when European explorers began traveling to the Southern Hemisphere. Twelve ancient constellations belong to the zodiac (straddling the ecliptic, which the Sun, Moon, and planets all traverse). The origins of the zodiac remain historically uncertain; its astrological divisions became prominent c. 400 BC in Babylonian or Chaldean astronomy, probably dates back to prehistory.

In 1928, the International Astronomical Union (IAU) formally accepted 88 modern constellations, with contiguous boundaries that together cover the entire celestial sphere. Any given point in a celestial coordinate system lies in one of the modern constellations. Some astronomical naming systems include the constellation where a given celestial object is found to convey its approximate location in the sky. The Flamsteed designation of a star, for example, consists of a number and the genitive form of the constellation name.

Other star patterns or groups called asterisms are not constellations per se but are used by observers to navigate the night sky. Asterisms often refer to several stars within a constellation or may share stars with several constellations. Examples include the Pleiades and Hyades within the constellation Taurus and the False Cross split between the southern constellations Carina and Vela, or Venus' Mirror in the constellation of Orion.

Dorado

Dorado (English pronunciation: ) is a constellation in the southern sky. It was named in the late 16th century and is now one of the 88 modern constellations. Its name refers to the dolphinfish (Coryphaena hippurus), which is known as dorado in Portuguese, although it has also been depicted as a swordfish. Dorado contains most of the Large Magellanic Cloud, the remainder being in the constellation Mensa. The South Ecliptic pole also lies within this constellation.

Even though the name Dorado is not Latin but Portuguese, astronomers give it the Latin genitive form Doradus when naming its stars; it is treated (like the adjacent asterism Argo Navis) as a feminine proper name of Greek origin ending in -ō (like Io or Callisto or Argo), which have a genitive ending -ūs.

Epsilon Boötis

Epsilon Boötis (ε Boötis, abbreviated Epsilon Boo, ε Boo), also named Izar, is a binary star in the northern constellation of Boötes. The star system can be viewed with the unaided eye at night, but resolving the pair with a small telescope is challenging; an aperture of 76 mm (3.0 in) or greater is required.

Ian Ridpath

Ian William Ridpath (born 1 May 1947, Ilford, Essex) is an English science writer and broadcaster best known as a popularizer of astronomy and a biographer of constellation history. As a UFO sceptic, he investigated and explained the Rendlesham Forest Incident of December 1980.

Jupiter

Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, but two-and-a-half times that of all the other planets in the Solar System combined. Jupiter and Saturn are gas giants; the other two giant planets, Uranus and Neptune, are ice giants. Jupiter has been known to astronomers since antiquity. It is named after the Roman god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, bright enough for its reflected light to cast shadows, and making it on average the third-brightest natural object in the night sky after the Moon and Venus.

Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, though helium comprises only about a tenth of the number of molecules. It may also have a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well-defined solid surface. Because of its rapid rotation, the planet's shape is that of an oblate spheroid (it has a slight but noticeable bulge around the equator). The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries. A prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope. Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere. Jupiter has 79 known moons, including the four large Galilean moons discovered by Galileo Galilei in 1610. Ganymede, the largest of these, has a diameter greater than that of the planet Mercury.

Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter. In late February 2007, Jupiter was visited by the New Horizons probe, which used Jupiter's gravity to increase its speed and bend its trajectory en route to Pluto. The latest probe to visit the planet is Juno, which entered into orbit around Jupiter on July 4, 2016. Future targets for exploration in the Jupiter system include the probable ice-covered liquid ocean of its moon Europa.

Karel Anděl

Karel Anděl (December 28, 1884 – March 17, 1947) was a Czech astronomer and selenographer. His Mappa Selenographica has been used in Norton's Star Atlas.

List of proper names of stars

This is a list of proper names of stars. These are the names of stars that have either been approved by the International Astronomical Union (its Working Group on Star Names has since 2016 been publishing a "List of IAU-approved Star Names", which as of June 2018 included a total of 330 proper names of stars) or which have been in somewhat recent usage. See also the lists of stars by constellation, which give variant names, derivations, and magnitudes.

Of the roughly 10,000 stars visible to the naked eye, only a few hundred have been given proper names in the history of astronomy. Traditional astronomy tends to group stars into asterisms, and give proper names to those, not to individual stars.

Many star names are in origin descriptive of the part of the asterism they are found in; thus Phecda, a corruption of the Arabic -فخذ الدب- fakhth al-dubb "thigh of the bear". Only a handful of the brightest stars have individual proper names not depending on their asterism; so Sirius "the scorcher", Antares and Canopus (of unknown origin), Alphard "the solitary one", Regulus "kinglet"; and arguably Aldebaran "the follower" (of the Pleiades), Procyon "preceding the dog [Sirius]". The same holds for Chinese star names, where most stars are enumerated within their asterisms, with a handful of exceptions such as 織女 "weaving girl" (Vega).

In addition to the limited number of traditional star names, there are some coined in modern times, e.g. "Avior" for Epsilon Carinae (1930), and a number of stars named after people (mostly in the 20th century).

Norton (surname)

Norton is a surname with origin from the basic Early English norþ + tun, meaning North settlement (cf Weston, Sutton and Easton for other surnames derived from points of the compass). There are many English villages called Norton or including Norton as part of the name, e.g. Midsomer Norton, Chipping Norton, Brize Norton etc. When surnames started to be used in the Middle Ages, a man from such a village might have the name added e.g. Tom of Norton. Alternatively a man from the north side of any village might be given the name Tom Norton to distinguish him from a Tom from the south side (Tom Sutton). A secondary source for the surname is from the anglicisation of Celtic (Irish and Scottish Gaelic) surnames (e.g. Naughtan). To confuse the situation further it is also sometimes found as a Jewish surname (probably from the anglicisation of the German surname Norden). The famous "Emperor Norton" in San Francisco was of Jewish origin from a South African settler family.

Photographic magnitude

Before the advent of photometers which accurately measure the brightness of astronomical objects, the apparent magnitude of an object was obtained by taking a picture of it with a camera. These images, made on orthochromatic photoemulsive film or plates, were more sensitive to the blue end of the visual spectrum than the human eye or modern photometers. As a result, bluer stars have a lower (i.e. brighter) photographic magnitude than their modern visual magnitude, because they appear brighter on the photograph than they do to modern photometers. Conversely, redder stars have a higher (i.e. fainter) photographic magnitude than visual magnitude, because they appear dimmer. For example, the red supergiant star KW Sagittarii has a photographic magnitude of 11.0 to 13.2 but a visual magnitude of about 8.5 to 11. It is also common for star charts to list a blue magnitude (B) such as with S Doradus and WZ Sagittae.

The symbol for apparent photographic magnitude is mpg and the symbol for absolute photographic magnitude is Mpg.The photographic magnitude scale is now considered obsolete.

Polaris

Polaris, designated Alpha Ursae Minoris (α Ursae Minoris, abbreviated Alpha UMi, α UMi), commonly the North Star or Pole Star, is the brightest star in the constellation of Ursa Minor. It is very close to the north celestial pole, making it the current northern pole star. The revised Hipparcos parallax gives a distance to Polaris of about 433 light-years (133 parsecs), while calculations by other methods derive distances around 30% closer.

Polaris is a multiple star, composed of the main star (Polaris Aa, a yellow supergiant) in orbit with a smaller companion (Polaris Ab); the pair in orbit with Polaris B (discovered in August 1779 by William Herschel). There were once thought to be two more distant components—Polaris C and Polaris D—but these have been shown not to be physically associated with the Polaris system.

Pole star

A pole star or polar star is a star, preferably bright, closely aligned to the axis of rotation of an astronomical object.

With regard to planet Earth, the pole star refers to Polaris (Alpha Ursae Minoris), a magnitude 2 star aligned approximately with its northern axis, and a pre-eminent star in celestial navigation.

Psi Cassiopeiae

Psi Cassiopeiae (ψ Cassiopeiae) is a binary star system in the northern constellation of Cassiopeia.

The primary component, ψ Cassiopeiae A, is an orange K-type giant with an apparent magnitude of +5.0; it is a double star, designated CCDM J01259+6808AB, with a fourteenth magnitude star (component B) located 3 arcseconds from the primary. Located about 25 arcseconds distant there is a 9.8 magnitude optical companion CCDM J01259+6808CD, designated ψ Cassiopeiae B in older star catalogues, which is itself another double; CD comprises a 9.4 magnitude component C and a 10 magnitude component D.

Struve 1694

Struve 1694 (Σ 1694, Struve 1694) is a double star in the constellation Camelopardalis.Σ 1694 is a double star, with components of magnitudes 5.3m and 5.9m:

Σ 1694A (HD 112028) is a white A-type giant star with an apparent magnitude of 5.28m. It is approximately 300 light years from Earth.

Σ 1694B (HD 112014) is a spectroscopic binary consisting of two A-type main sequence stars.Norton's Star Atlas describes the pair as yellowish and bluish.Σ 1694 was also known as 32H. Camelopardalis, Hevelius' 32nd of Camelopardalis. It is not Flamsteed's "32 Camelopardalis", which is ξ Aurigae. In the British Association Catalogue, the star pair are listed as being in Ursa Minor.

True north

True north (also called geodetic north) is the direction along Earth's surface towards the geographic North Pole or True North Pole.

Geodetic north differs from magnetic north (the direction a compass points toward the Magnetic North Pole), and from grid north (the direction northwards along the grid lines of a map projection). Geodetic true north also differs very slightly from astronomical true north (typically by a few arcseconds) because the local gravity may not point at the exact rotational axis of Earth.

The direction of astronomical true north is marked in the skies by the north celestial pole. This is within about 1° of the position of Polaris, so that the star would appear to trace a tiny circle in the sky each sidereal day. Due to the axial precession of Earth, true north rotates in an arc with respect to the stars that takes approximately 25,000 years to complete. Around 2100–02, Polaris will make its closest approach to the celestial north pole (extrapolated from recent Earth precession). The visible star nearest the north celestial pole 5,000 years ago was Thuban.On maps published by the United States Geological Survey (USGS) and the United States Armed Forces, true north is marked with a line terminating in a five-pointed star. The east and west edges of the USGS topographic quadrangle maps of the United States are meridians of longitude, thus indicating true north (so they are not exactly parallel). Maps issued by the United Kingdom Ordnance Survey contain a diagram showing the difference between true north, grid north, and magnetic north at a point on the sheet; the edges of the map are likely to follow grid directions rather than true, and the map will thus be truly rectangular/square.

YZ Cassiopeiae

YZ Cassiopeiae (21 Cas) is a star system 103.8 parsecs (339 ly) away from Earth, in the constellation Cassiopeia. It comprises three stars: an eclipsing Algol-type binary and a visually fainter star about 3000 AU distant.The primary star in the YZ Cassiopeiae system is a white subgiant (main sequence) star of spectral type A1Vm and 2.31 solar masses (M☉) with a less massive main sequence dwarf star of type F2V and 1.35 M☉. The apparent magnitude of the eclipsing binary varies from 5.65 to 6.05 with a period of 4.4672 days. Combined, they appear to have a spectral type of A2IV.The binary has a dimmer (magnitude 9.7 according to Norton, or 10.5 by SIMBAD) companion of 0.8 M☉ orbiting with a period of about 86 580 years.

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