Amateur astronomy in the context of Celestial objects

Celestial cartography, uranography,astrography or star cartography is the aspect 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 uses databases of stars and of other astronomical objects.

In amateur astronomy, "GoTo" refers to a type of telescope mount and related software that can automatically point a telescope at astronomical objects that the user selects. Both axes of a GoTo mount are driven by a motor and controlled by a computer. It may be either a microprocessor-based integrated controller or an external personal computer. This differs from the single-axis semi-automated tracking of a traditional clock-drive equatorial mount.

The user can command the mount to point the telescope to the celestial coordinates that the user inputs, or to objects in a pre-programmed database including ones from the Messier catalogue, the New General Catalogue, and even major Solar System bodies (the Sun, Moon, and planets).

The Hubble sequence is a morphological classification scheme for galaxies published by Edwin Hubble in 1926. It is often colloquially known as the Hubble tuning-fork diagram because the shape in which it is traditionally represented resembles a tuning fork.It was invented by John Henry Reynolds and Sir James Jeans.

The tuning fork scheme divided regular galaxies into three broad classes – ellipticals, lenticulars and spirals – based on their visual appearance (originally on photographic plates). A fourth class contains galaxies with an irregular appearance. The Hubble sequence is the most commonly used system for classifying galaxies, both in professional astronomical research and in amateur astronomy.

Printed calendars, in addition to its main function to display dates and related information, usually in a table format, also often contain additional information relevant for specific groups – for instance, a Christian liturgical calendar will show holy days and liturgical colours, while a calendar for amateur astronomers will highlight phases of the moon, conjunctions and eclipses. Calendars for general public may also contain various interesting facts (e.g., associated with anniversaries of important people or important events). Various facts were also printed on the back sides of the sheets of a tear-off calendar. In modern times, calendars may also have a decorative purpose.

A small telescope is generally considered by professional astronomers to be any reflecting telescope with a primary mirror that is less than 2 metres (80 in) in diameter.By amateur standards, a small telescope can have a primary mirror/aperture less than 6–10 inches (150–250 mm) in diameter. Little if any professional-level research is performed with refracting telescopes in the modern era of astronomy.

Small telescopes dominate astronomical research in the fields of asteroid/comet discovery/observation, variable star photometry, supernova/nova discovery, and colorimetry/polarimetry of the Solar System's planets.

An astronomical filter is a telescope accessory consisting of an optical filter used by amateur astronomers to improve the details and contrast of celestial objects, either for viewing or for photography. Research astronomers, on the other hand, use various band-pass filters for photometry on telescopes, in order to obtain measurements which reveal objects' astrophysical properties, such as stellar classification and placement of a celestial body on its Wien curve.

Most astronomical filters work by blocking a specific part of the color spectrum above and below a bandpass, significantly increasing the signal-to-noise ratio of the interesting wavelengths, and so making the object gain detail and contrast. While the color filters transmit certain colors from the spectrum and are usually used for observation of the planets and the Moon, the polarizing filters work by adjusting the brightness, and are usually used for the Moon. The broad-band and narrow-band filters transmit the wavelengths that are emitted by the nebulae (by the hydrogen and oxygen atoms), and are frequently used for reducing the effects of light pollution.

Astronomical Society Ruđer Bošković (Serbian: Астрономско друштво Руђер Бошковић, romanized: Astronomsko društvo Ruđer Bošković) is an astronomical society in Belgrade, Serbia. Founded in 1934 by a group of students, it is the oldest one in the Balkans. Initially it had only a few members, but it now has more than 700. It is named after Ruđer Bošković.

The main role of the society is popularization of astronomy. The society also practices amateur astronomy observations. To accomplish this, in 1964, the Society founded the Public Observatory, which is still located in adapted Despot's Tower in Kalemegdan, Belgrade. The Belgrade Planetarium, one of the only two planetariums in Serbia, is also founded by the society, in 1970. It is located in the lower part of Kalemegdan Fortress, in a former Turkish bath. The society has published a popular science magazine called Vasiona since 1953.

Messier 81 (also known as NGC 3031 or Bode's Galaxy) is a grand design spiral galaxy about 12 million light-years away in the constellation Ursa Major. It has a D₂₅ isophotal diameter of 29.44 kiloparsecs (96,000 light-years). Because of its relative proximity to the Milky Way galaxy, large size, and active galactic nucleus (which harbors a 70 million M_☉supermassive black hole), Messier 81 has been studied extensively by professional astronomers. The galaxy's large size and relatively high brightness also makes it a popular target for amateur astronomers. In late February 2022, astronomers reported that M81 may be the source of FRB 20200120E, a repeating fast radio burst.

The Cat's Eye Nebula (also known as NGC 6543 and Caldwell 6) is a planetary nebula in the northern constellation of Draco, discovered by William Herschel on February 15, 1786. It was the first planetary nebula whose spectrum was investigated by the English amateur astronomer William Huggins, demonstrating that planetary nebulae were gaseous and not stellar in nature. Structurally, the object has had high-resolution images by the Hubble Space Telescope revealing knots, jets, bubbles and complex arcs, being illuminated by the central hot planetary nebula nucleus (PNN).It is a well-studied object that has been observed from radio to X-ray wavelengths. At the centre of the Cat's Eye Nebula is a dying Wolf–Rayet star, the sort of which can be seen in the Webb Telescope's image of WR 124. The Cat's Eye Nebula's central star shines at magnitude +11.4. Hubble Space Telescope images show a sort of dart board pattern of concentric rings emanating outwards from the centre.

The Whirlpool Galaxy, also known as Messier 51a (M51a) or NGC 5194, is an interacting grand-design spiral galaxy with a Seyfert 2 active galactic nucleus. It lies in the constellation Canes Venatici, and was the first galaxy to be classified as a spiral galaxy. It is 31 million lightyears (9.5 megaparsecs/Mpc) away and 23.58 kiloparsecs (76,900 ly) in diameter.

The galaxy and its companion, NGC 5195, are easily observed by amateur astronomers, and the two galaxies may be seen with binoculars. The Whirlpool Galaxy has been extensively observed by professional astronomers, who study it and its pair with dwarf galaxy NGC 5195 to understand galaxy structure (particularly structure associated with the spiral arms) and galaxy interactions. Its pair with NGC 5195 is among the most famous and relatively close interacting systems, and thus is a favorite subject of galaxy interaction models.

Boyden Observatory is an astronomical research observatory and science education centre located in Maselspoort, 20 kilometres (12 mi) north-east of the city of Bloemfontein in Free State, South Africa. The observatory is managed by the Physics Department of the University of the Free State (UFS). The Friends of Boyden assist the observatory as a public support group, organising open evenings and protecting its public interest. Boyden also makes use of members of ASSA Bloemfontein Centre, the amateur astronomy club of the city, for presenters and telescope assistants.

DarkSky International, formerly the International Dark-Sky Association (IDA), is a United States–based nonprofit organization incorporated in 1988 by founders David Crawford, a professional astronomer, and Tim Hunter, a physician and amateur astronomer. The mission of DarkSky is "to preserve and protect the night time environment and our heritage of dark skies through quality outdoor lighting".

Light pollution is the result of outdoor lighting that is not properly shielded, allowing light shine into the eyes and night sky. Direct light that shines into the eyes is called glare, and light directed into the night sky above the horizon causes skyglow. Lighting can also cause light trespass when it enters areas where unwanted (e.g. a neighbor's yard and windows). DarkSky is the first and currently the largest organization in the dark-sky movement.

Timothy B. Hunter, better known as Tim Hunter, is an American radiologist and amateur astronomer, who was the president of the International Dark-Sky Association.

Cuno Hoffmeister (2 February 1892 – 2 January 1968) was a German astronomer, observer and discoverer of variable stars, comets and minor planets, and founder of Sonneberg Observatory.

Born in Sonneberg in 1892 to Carl and Marie Hoffmeister, Cuno Hoffmeister obtained his first telescope in 1905 and became an avid amateur astronomer. After his father lost most of his money in 1914, Hoffmeister had to leave school in 1916 to start an apprenticeship in his father's company. During this time he continued to study spherical mathematics and trigonometry. In April 1915 he had the opportunity to substitute as the assistant of Ernst Hartwig at Remeis Observatory in Bamberg while the current holder of the position was drafted, mainly working on observations of meteors and variable stars. He held this position until the end of the war and then moved back to Sonneberg, where he made his Abitur in 1920.

Lynx is a constellation named after the animal, usually observed in the Northern Celestial Hemisphere. The constellation was introduced in the late 17th century by Johannes Hevelius. It is a faint constellation, with its brightest stars forming a zigzag line. The orange giant Alpha Lyncis is the brightest star in the constellation, and the semiregular variable star Y Lyncis is a target for amateur astronomers. Six star systems have been found to contain planets. Those of 6 Lyncis and HD 75898 were discovered by the Doppler method; those of XO-2, XO-4, XO-5 and WASP-13 were observed as they passed in front of the host star.

Within the constellation's borders lie NGC 2419, an unusually remote globular cluster; the galaxy NGC 2770, which has hosted three recent Type Ib supernovae; the distant quasar APM 08279+5255, whose light is magnified and split into multiple images by the gravitational lensing effect of a foreground galaxy; and the Lynx Supercluster, which was the most distant supercluster known at the time of its discovery in 1999.

John E. Bortle is an American amateur astronomer. He is best known for creating the Bortle scale to quantify the darkness of the night sky.

Bortle has made a special study of comets. He has recorded thousands of observations relating to more than 300 comets. From 1977 until 1994 he authored the monthly '"Comet Digest" in Sky and Telescope magazine. He also had a special interest in variable stars. After joining the AAVSO in 1963, Bortle contributed more than 215,000 visual observations to the AAVSO's database before retiring from the organization in 2020.. From 1970 until 2000 he edited the monthly AAVSO circular for the American Association of Variable Star Observers. He published his darkness scale in Sky and Telescope magazine in 2001. The scale ranges from 1 (extremely dark rural area or national park, usually at high elevation, low humidity, and low wind) to 9 (urban inner city). Today that scale is widely used throughout the world by the amateur astronomy community for ascertaining and relating their sky conditions to colleagues.

Sky & Telescope (S&T) is a monthly magazine covering all aspects of amateur and professional astronomy, including what to see in the sky tonight and new findings in astronomy. Other topics covered include:

• observing guides for planets, galaxies, star clusters, and other objects visible in the night sky
• reviews of telescopes and other astronomical equipment, books, and software
• events in the amateur astronomy community
• amateur telescope making
• astrophotography

The articles are intended for the informed lay reader and include detailed discussions of current discoveries, frequently by participating scientists. The magazine is illustrated in full color, with both amateur and professional photography of celestial sights, as well as tables and charts of upcoming celestial events.