Deep-sky object

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"Deep sky" redirects here. For the racehorse, see Deep Sky (horse). For the 2023 documentary, see Deep Sky. For the band, see Deepsky.
Several nebulae in the constellation Orion commonly called deep-sky objects

A deep-sky object (DSO) is any

amateur astronomers to denote visually observed faint naked eye and telescopic objects such as star clusters, nebulae and galaxies
. This distinction is practical and technical, implying a variety of instruments and techniques appropriate to observation, and does not distinguish the nature of the object itself.

Origins and classification

Classifying non-stellar astronomical objects began soon after the invention of the telescope.

Messier catalog, which included 103 "nebulae" and other faint fuzzy objects he considered a nuisance since they could be mistaken for comets, the objects he was actually searching for.[3] As telescopes improved these faint nebulae would be broken into more descriptive scientific classifications such as interstellar clouds
, star clusters, and galaxies.

"Deep-sky object", as an astronomical classification for these objects, has its origins in the modern field of amateur astronomy. The origin of the term is unknown but it was popularized by

Sue French.[citation needed] Houston's columns, and later book compilations of those columns, helped popularize the term,[5]
each month giving the reader a guided tour of a small part of the sky highlighting well known and lesser known objects for binoculars and small telescopes.

Observations and activities

Map of the constellation Cygnus marking the location of bright and more challenging deep-sky objects

There are many amateur astronomical techniques and activities associated with deep-sky objects. Some of these objects are bright enough to find and see in binoculars and small telescopes. But the faintest objects need the

Dobsonian style telescopes, with wide fields of view well suited to such observing.[7] Observing faint objects needs dark skies, so these relatively portable types of telescopes also lend themselves to the majority of amateurs who need to travel outside light polluted urban locations.[8] To cut down light pollution and enhance contrast, observers employ "nebular filters
" designed to admit certain wavelengths of light, and block others.

There are organized activities associated with DSOs such as the

telescopes and experienced amateur astronomers.[citation needed
]

List of deep-sky object types

There are many astronomical object types that come under the description of deep-sky objects. Since the definition is objects that are non-Solar System and non-stellar the list includes:[9]

See also

References

  1. ISBN 978-0-8050-4668-7
    .
  2. ISBN 978-0-8230-2512-1
    .
  3. ^
    ISBN 978-0-19-286203-7
    .
  4. ^ Charles Anthony Federer (1942). Sky and Telescope. Sky Publishing Corporation.
  5. ISBN 978-0-8050-4668-7
    .
  6. ISBN 978-1-85233-273-0
    .
  7. ISBN 978-0-9689141-8-2
    .
  8. ^ The Observer's Handbook, Royal Astronomical Society of Canada, p. 63
  9. ISBN 978-1-85233-691-2
    .

Further reading

External links
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