Editing Astrophotography (section)

==History==
[[File:Henry Draper.jpg|thumb|Henry Draper with a refractor telescope set up for photography (photo probably taken in the 1860s or early 1870).<ref>[http://hastingshistoricalsociety.blogspot.com/2010/04/house-tour-preview-henry-drapers.html Hastings Historical Society (blogspot.com)], Thursday, April 15, 2010, House Tour Preview: Henry Draper’s Observatory</ref>]]
The development of astrophotography as a scientific tool was pioneered in the mid-19th century for the most part by experimenters and [[amateur astronomers]], or so-called "[[gentleman scientist]]s" (although, as in other scientific fields, these were not always men). Because of the very long exposures needed to capture relatively faint astronomical objects, many technological problems had to be overcome. These included making telescopes rigid enough so they would not sag out of focus during the exposure, building clock drives that could rotate the telescope mount at a constant rate, and developing ways to accurately keep a telescope aimed at a fixed point over a long period of time. Early photographic processes also had limitations. The [[daguerreotype]] process was far too slow to record anything but the brightest objects, and the wet plate [[collodion]] process limited exposures to the time the plate could stay wet.<ref>[http://books.nap.edu/html/biomems/hdraper.pdf Memoir, Henry Draper 1837–1882], George F. Barker read before the National Academy, April 18, 1888.</ref>

[[File:John W Draper-The first Moon Photograph 1840.jpg|thumb|upright=0.9|The earliest surviving dagerrotype of the Moon by Draper (1840)]]
The first known attempt at astronomical photography was by [[Louis Jacques Mandé Daguerre]], inventor of the daguerreotype process which bears his name, who attempted in 1839 to photograph the [[Moon]]. Tracking errors in guiding the telescope during the long exposure meant the photograph came out as an indistinct fuzzy spot. [[John William Draper]], New York University Professor of Chemistry, physician and scientific experimenter managed to make the first successful photograph of the Moon a year later on March 23, 1840, taking a 20-minute-long [[daguerreotype]] image using a {{convert|5|in|cm|adj=on}} [[reflecting telescope]].<ref>{{cite journal |last1=Trombino |first1=Don |title=Dr. John William Draper |journal=Journal of the British Astronomical Association |date=1980 |volume=90 |pages=565–571 |bibcode=1980JBAA...90..565T |url=https://adsabs.harvard.edu/full/1980JBAA...90..565T}}</ref>

The Sun may have been first photographed in an 1845 daguerreotype by the French physicists [[Léon Foucault]] and [[Hippolyte Fizeau]]. A failed attempt to obtain a photograph of a Total Eclipse of the Sun was made by the Italian physicist, Gian Alessandro Majocchi during an eclipse of the Sun that took place in his home city of Milan, on July 8, 1842. He later gave an account of his attempt and the Daguerreotype photographs he obtained, in which he wrote:
{{quote|A few minutes before and after totality an iodized plate was exposed in a camera to the light of the thin crescent, and a distinct image was obtained, but another plate exposed to the light of the corona for two minutes during totality did not show the slightest trace of photographic action. No photographic alteration was caused by the light of the corona condensed by a lens for two minutes, during totality, on a sheet of paper prepared with bromide of silver.<ref>{{cite journal |first1=Andrew Ainslie |last1=Common |first2=Albert |last2=Taylor |name-list-style=amp |title=Eclipse Photography |journal=American Journal of Photography |year=1890 |pages=203–209 }}</ref>}}

[[File:1851 07 28 Berkowski.jpg|thumb|upright=0.9|The first solar eclipse photograph was taken on July 28, 1851, by a daguerrotypist named Berkowski.]]
The Sun's solar corona was first successfully imaged during the [[Solar eclipse of July 28, 1851]]. Dr. August Ludwig Busch, the Director of the Königsberg Observatory gave instructions for a local daguerreotypist named Johann Julius Friedrich Berkowski to image the eclipse. Busch himself was not present at [[Königsberg]] (now [[Kaliningrad]], Russia), but preferred to observe the eclipse from nearby Rixhoft. The telescope used by Berkowski was attached to {{convert|6+1/2|in|cm|adj=on}} Königsberg [[heliometer]] and had an aperture of only {{cvt|2.4|in|cm}}, and a focal length of {{cvt|32|in|cm}}. Commencing immediately after the beginning of totality, Berkowski exposed a daguerreotype plate for 84 seconds in the focus of the telescope, and on developing an image of the corona was obtained. He also exposed a second plate for about 40 to 45 seconds but was spoiled when the Sun broke out from behind the Moon.<ref>{{cite book |chapter=On the Berkowski daguerreotype (Königsberg, 1851 July 28): the first correctly-exposed photograph of the solar corona |first1=Reinhard E. |last1=Schielicke |first2=Axel D. |last2=Wittmann |pages=128–147 |title=Development of Solar Research / Entwicklung der Sonnenforschung |editor-first=A. D. |editor-last=Wittmann |editor2-first=G. |editor2-last=Wolfschmidt |editor3-first=H. W. |editor3-last=Duerbeck |year=2005 |publisher=Deutsch |isbn=3-8171-1755-8 }}</ref> More detailed photographic studies of the Sun were made by the British astronomer [[Warren De la Rue]] starting in 1861.<ref>{{cite book|author=Edward Emerson Barnard|title=Astronomical Photography|url=https://books.google.com/books?id=erh_Fx5LpasC&pg=PA66|year=1895|page=66}}</ref>

The first photograph of a star other than the Sun was a daguerreotype of the star [[Vega]] by astronomer [[William Cranch Bond]] and daguerreotype photographer and experimenter [[John Adams Whipple]], on July 16 and 17, 1850 with [[Harvard College Observatory]]'s 15&nbsp;inch [[Great refractor]].<ref>{{cite web|url=https://hco.cfa.harvard.edu/facilities/GreatRefractor|title=The Great Refractor|publisher=[[Harvard College Observatory]]|access-date=2021-05-18|quote=In 1850 [...] the first daguerreotype ever made of a star, the bright Vega, was taken by J.A. Whipple working under W.C. Bond}}</ref> In 1863 the English chemist [[William Allen Miller]] and English amateur astronomer Sir [[William Huggins]] used the wet collodion plate process to obtain the first ever photographic [[spectrogram]] of a star, [[Sirius]] and [[Capella (star)|Capella]].<ref name="ASTROLab">[http://astro-canada.ca/_en/a2311.html Spectrometers, ASTROLab of Mont-Mégantic National Park]</ref> In 1872 American physician [[Henry Draper]], the son of John William Draper, recorded the first spectrogram of a star (Vega) to show [[absorption lines]].<ref name="ASTROLab"/>
[[File:Henry Drape Orion nebula 1880 inverted.jpg|thumb|Henry Draper's 1880 photograph of the Orion Nebula, the first ever taken.]]
[[File:Orion-Nebula A A Common.jpg|thumb|One of Andrew Ainslie Common's 1883 photographs of the same nebula, the first to show that a long exposure could record stars and nebulae invisible to the human eye.]]
Astronomical photography did not become a serious research tool until the late 19th century, with the introduction of [[dry plate]] photography.<ref>{{cite book|first1=Anton |last1=Sebastian |author-link1=Anton Sebastian |title=A Dictionary of the History of Science|url=https://books.google.com/books?id=JKMNuwMAmr4C&pg=PA75|year=2001|publisher=Taylor & Francis|isbn=978-1-85070-418-8|page=75}}</ref> It was first used by Sir William Huggins and his wife [[Margaret Lindsay Huggins]], in 1876, in their work to record the spectra of astronomical objects. In 1880, Henry Draper used the new dry plate process with photographically corrected {{cvt|11|in|cm|adj=on}} [[refracting telescope]] made by [[Alvan Clark]]<ref>[http://loen.ucolick.org/12-inch_Refurb_Project/History/index.htm loen.ucolick.org, Lick Observatory 12-inch Telescope]</ref> to make a 51-minute exposure of the [[Orion Nebula]], the first photograph of a nebula ever made. A breakthrough in astronomical photography came in 1883, when amateur astronomer [[Andrew Ainslie Common]] used the dry plate process to record several images of the same nebula in exposures up to 60 minutes with a {{cvt|36|in|cm|adj=on}} reflecting telescope that he constructed in the backyard of his home in Ealing, outside London. These images for the first time showed stars too faint to be seen by the human eye.<ref>{{cite book|author=J. B. Hearnshaw|title=The Measurement of Starlight: Two Centuries of Astronomical Photometry|url=https://archive.org/details/measurementofsta0000hear|url-access=registration|year=1996|publisher=Cambridge University Press|isbn=978-0-521-40393-1|page=[https://archive.org/details/measurementofsta0000hear/page/122 122]}}</ref>
<ref>[http://www.ucolick.org/public/telescopes/crossley.html UCO Lick Observatory page on the Crossley telescope]</ref>

The first all-sky photographic [[astrometry]] project, [[Carte du Ciel|Astrographic Catalogue and Carte du Ciel]], was started in 1887. It was conducted by 20 observatories all using special photographic telescopes with a uniform design called ''normal [[astrograph]]s'', all with an aperture of around {{cvt|13|in|mm}} and a focal length of {{cvt|11|ft|m}}, designed to create images with a uniform scale on the photographic plate of approximately 60 [[Arc minute|arcsecs]]/mm while covering a 2° × 2° field of view. The attempt was to accurately map the sky down to the 14th [[Magnitude (astronomy)|magnitude]] but it was never completed.

The beginning of the 20th century saw the worldwide construction of refracting telescopes and sophisticated large reflecting telescopes specifically designed for photographic imaging. Towards the middle of the century, giant telescopes such as the [[Hale Telescope|{{cvt|200|in|m|adj=on}} Hale Telescope]] and the {{cvt|48|in|cm|adj=on}} [[Samuel Oschin telescope]] at [[Palomar Observatory]] were pushing the limits of film photography.

Some progress was made in the field of photographic emulsions and in the techniques of [[Forming gas|forming gas hypersensitization]], cryogenic cooling,<ref>See for example, U.S. Patent No. 4,038,669, Cryogenic Cameras, John M. Guerra, July 26, 1977.</ref> and light amplification, but starting in the 1970s after the invention of the CCD, photographic plates were gradually replaced by electronic imaging in professional and amateur observatories. CCD's are far more light sensitive, do not drop off in sensitivity over long exposures the way film does ("[[reciprocity failure]]"), have the ability to record in a much wider spectral range, and simplify storage of information. Telescopes now use many configurations of CCD sensors including linear arrays and large mosaics of CCD elements equivalent to 100 million pixels, designed to cover the focal plane of telescopes that formerly used {{convert|10-14|in|cm|adj=on}} photographic plates.{{cn|date=August 2022}}

[[File:HST-SM4.jpeg|thumb|The [[Hubble Space Telescope]] shortly after the [[STS-125]] maintenance mission in 2009.]]

The late 20th century saw advances in astronomical imaging take place in the form of new hardware, with the construction of giant multi-mirror and [[segmented mirror]] telescopes. It would also see the introduction of space-based telescopes, such as the [[Hubble Space Telescope]]. Operating outside the atmosphere's turbulence, scattered ambient light and the vagaries of weather allows the Hubble Space Telescope, with a mirror diameter of {{convert|2.4|m|in}}, to record stars down to the 30th magnitude, some 100 times dimmer than what the 5-meter Mount Palomar Hale Telescope could record in 1949.