Editing Arecibo Observatory

{{Infobox telescope
| image= The Arecibo Observatory 20151101114231-0 8e7cc c7a44aca orig.jpg
| caption= Arecibo Observatory radio telescope
| locmapin = Puerto Rico
| nrhp         = {{Infobox NRHP
| embed = yes
| name = National Astronomy and Ionosphere Center
| nrhp_type = hd | nocat = yes
| nearest_city =Arecibo
| area = {{convert|118|acre|m2}}
| built = 
| architect = Gordon, William E; [[Thomas Christian Kavanagh|Kavanaugh, T.C.]]
| engineer = von Seb, Inc., [[Thomas Christian Kavanagh|T.C. Kavanaugh]] of Praeger-Kavanagh, and [[Severud Associates|Severud-Elstad-Krueger Associates]]<ref>{{Cite journal |url=http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6433355|title=Radio-Radar Telescope Will Probe Solar System|journal=Electrical Engineering|volume=80|issue=7|pages=561|date=July 1961|accessdate=2016-07-31|doi=10.1109/EE.1961.6433355}}</ref>
| architecture = 
| added = September 23, 2008<ref name=newlistings20081003>{{cite web| url=http://www.nps.gov/history/nr/listings/20081003.HTM| title=Weekly List Actions| author=National Park Service| date=October 3, 2008| accessdate=February 6, 2018}}</ref>
| visitation_num = 
| visitation_year = 
| refnum = 07000525
| mpsub = 
| governing_body = Federal
}}
}}

The '''Arecibo Observatory''' is a [[radio telescope]] in the municipality of [[Arecibo, Puerto Rico|Arecibo]], [[Puerto Rico]]. This [[observatory]] is operated by [[University of Central Florida]], Yang Enterprises and [[Metropolitan University (Puerto Rico)|UMET]], under cooperative agreement with the US [[National Science Foundation]] (NSF).<ref>{{cite news |url=http://www.sciencemag.org/news/2018/02/iconic-arecibo-radio-telescope-saved-university-consortium |title=Iconic Arecibo radio telescope saved by university consortium |work=[[Science (journal)|Science]] |date=22 Feb 2018 |deadurl=yes |df=mdy-all |access-date=March 3, 2018 |archive-url=https://web.archive.org/web/20180304172439/http://www.sciencemag.org/news/2018/02/iconic-arecibo-radio-telescope-saved-university-consortium |archive-date=March 4, 2018 }}</ref><ref name="ucf">{{cite pressrelease|url=https://today.ucf.edu/ucf-led-consortium-manage-arecibo-observatory-puerto-rico/|title=UCF-led Consortium to Manage Arecibo Observatory in Puerto Rico|publisher=[[UCF Today]]|date=2018-02-22}}</ref> The observatory is the sole facility of the '''National Astronomy and Ionosphere Center''' ('''NAIC'''), which is the formal name of the observatory.<ref name="2010RFP"/> From its construction in the 1960s until 2011, the observatory was managed by [[Cornell University]].

For more than 50 years, from its completion in 1963 until July 2016 when the [[Five hundred meter Aperture Spherical Telescope]] (FAST) in China was completed, the Arecibo Observatory's {{convert|1000|ft|0|abbr=off|adj=on|sp=us}} [[radio telescope]] was the world's largest single-aperture telescope. It is used in three major areas of research: [[radio astronomy]], [[atmospheric science]], and [[radar astronomy]]. Scientists who want to use the observatory submit proposals that are evaluated by an independent scientific board.

The observatory has appeared in film, gaming and television productions, gaining more recognition in 1999 when it began to collect data for the [[SETI@home]] project. It has been listed on the US [[National Register of Historic Places]] starting in 2008.<ref name="newlistings20081003"/><ref name="nrhpreg">{{cite web |title=National Register of Historic Places Registration: National Astronomy and Ionosphere Center / Arecibo Observatory |url=http://www.nps.gov/history/nr/feature/weekly_features/IonosphereCenter.pdf |date=March 20, 2007 |author=Juan Llanes Santos |publisher=[[National Park Service]] |accessdate=October 21, 2009}} (72 pages, with many historic b&w photos and 18 color photos)</ref> It was the featured listing in the US [[National Park Service]]'s weekly list of October 3, 2008.<ref name="featured">{{cite web|url=http://www.nps.gov/history/nr/nrlist.htm |title=Weekly List Actions |accessdate=October 21, 2009 |publisher=National Park Service| archiveurl= https://web.archive.org/web/20091202223221/http://www.nps.gov/history/nr/nrlist.htm| archivedate= December 2, 2009 <!--DASHBot-->| deadurl= no}}</ref> The center was named an [[List of IEEE milestones|IEEE Milestone]] in 2001.<ref>{{cite web |url=http://www.ieeeghn.org/wiki/index.php/Milestones:NAIC/Arecibo_Radiotelescope,_1963 |title=Milestones:NAIC/Arecibo Radiotelescope, 1963 |work=IEEE Global History Network |publisher=[[IEEE]] |accessdate=July 29, 2011}}</ref> It has a visitor center that is open part-time.<ref>[http://www.naic.edu/general/index.php?option=com_content&view=article&id=162:vc-description&catid=107&Itemid=638 Visitor Center] {{webarchive|url=https://web.archive.org/web/20130106095641/http://www.naic.edu/general/index.php?option=com_content&view=article&id=162%3Avc-description&catid=107&Itemid=638 |date=January 6, 2013 }}</ref>

On September 21, 2017, high winds associated with [[Hurricane Maria]] caused the 430&nbsp;MHz line feed to break and fall onto the primary dish, damaging about 30 out of 38,000 aluminum panels.  Most Arecibo observations do not use the line feed but instead rely on the feeds and receivers located in the dome.  Overall, the damage inflicted by Maria was minimal.<ref>{{cite web|url=https://www.washingtonpost.com/news/speaking-of-science/wp/2017/09/20/arecibo-observatory-puerto-ricos-famous-radio-telescope-is-battered-by-hurricane-maria/|title=Arecibo Observatory, Puerto Rico's famous telescope, is battered by Hurricane Maria|last=Kaplan|first=Sarah|work=[[The Washington Post]]|date=September 22, 2017}}</ref><ref>{{cite web|url=http://news.nationalgeographic.com/2017/09/arecibo-radio-telescope-damaged-puerto-rico-hurricane-maria-science/|title=Hurricane Damages Giant Radio Telescope—Why It Matters|last=Drake|first=Nadia|work=[[National Geographic (magazine)|National Geographic]]|date=September 22, 2017}}</ref><ref name="auto">{{cite news|title=Damage to Arecibo less than feared |url=http://spacenews.com/damage-to-arecibo-less-than-feared/|work=[[SpaceNews]] |first=Jeff|last= Foust |date=September 27, 2017 |accessdate= February 5, 2018}}</ref><ref name="auto1">{{cite news|title=Good news, earthlings! Puerto Rico telescope still guarding the galaxy despite Maria|url=http://www.miamiherald.com/news/nation-world/world/americas/article180486971.html|work=[[Miami Herald]]|date=2017-10-23|language=en}}</ref>

== General information ==
The main collecting dish is {{convert|305|m|ft|abbr=on|sigfig=2}} in diameter, constructed inside the depression left by a [[karst]] [[sinkhole]].<ref>{{cite web| url=http://www.news.cornell.edu/releases/Jan03/NAIC.director.deb.html| title=Astrophysicist Robert Brown, leader in telescope development, named to head NAIC and its main facility, Arecibo Observatory| author=David Brand| publisher=[[Cornell University]]| date=21 January 2003| accessdate=2008-09-02}}</ref>  The dish surface is made of 38,778 perforated aluminum panels, each about {{convert|3|by|6|ft|m|0}}, supported by a mesh of steel cables. The ground beneath is accessible and supports shade-tolerant vegetation.<ref>{{cite web|title=General Views of the Arecibo Observatory|url=http://www.naic.edu/public/about/photos/hires/ao010.jpg|work=Image Gallery|publisher=Arecibo Observatory|accessdate=25 August 2013}}</ref>

The observatory has four [[radar]] transmitters, with [[EIRP|effective isotropic radiated powers]] of 20&nbsp;[[Watt#Terawatt|TW]] (continuous) at 2380&nbsp;MHz, 2.5&nbsp;[[Watt#Terawatt|TW]] (pulse peak) at 430&nbsp;MHz, 300&nbsp;[[Watt#Megawatt|MW]] at 47&nbsp;MHz, and 6&nbsp;[[Watt#Megawatt|MW]] at 8&nbsp;MHz.

The reflector is a [[spherical reflector]], not a [[parabolic reflector]]. To aim the device, the receiver is moved to intercept signals reflected from different directions by the spherical dish surface of {{convert|870|ft|abbr=on|order=flip}} radius.<ref>{{Cite journal|title=Genesis of the 1000-foot Arecibo dish|journal=Journal of Astronomical History and Heritage|volume=12|issue=2|pages=141|author=Cohen, M. H.|bibcode=2009JAHH...12..141C|year=2009}}</ref> A parabolic mirror would have varying [[Astigmatism (optical systems)|astigmatism]] when the receiver is off the focal point, but the [[spherical aberration|error of a spherical mirror]] is uniform in every direction.

The receiver is on a 900-ton platform suspended {{convert|150|m|ft|abbr=on|sigfig=3}} above the dish by 18 cables running from three [[reinforced concrete]] towers, one {{convert|365|ft|m|abbr=on|order=flip}} high and the other two {{convert|265|ft|abbr=on|order=flip}} high, placing their tops at the same elevation. The platform has a rotating, bow-shaped track {{convert|93|m|ft|abbr=on|sigfig=3}} long, called the [[azimuth]] arm, carrying the receiving antennas and secondary and tertiary reflectors. This allows the telescope to observe any region of the sky in a forty-degree cone of visibility about the local [[zenith]] (between −1 and 38 degrees of [[declination]]). [[Puerto Rico]]'s location near the Northern [[Tropic of Cancer|Tropic]] allows Arecibo to view the planets in the Solar System over the Northern half of their orbit. The round trip light time to objects beyond [[Saturn]] is longer than the 2.6 hour time that the telescope can track a celestial position, preventing [[radar]] observations of more distant objects.

{{Wide image|Panorama arecibo telescope from observation deck.jpg|800px|The Arecibo Radio Telescope as viewed from the observation deck, October 2013}}