Editing Wow! signal (section)

== Background ==
In a 1959 paper, [[Cornell University]] physicists [[Philip Morrison]] and [[Giuseppe Cocconi]] had speculated that any [[extraterrestrial civilization]] attempting to communicate via radio signals might do so using a frequency of {{val|1420}} [[megahertz]] ({{val|21}}-centimeter [[spectral line]]), which is [[Hydrogen line|naturally emitted by hydrogen]], the most common element in the universe and therefore likely familiar to all technologically advanced civilizations.<ref name="Nat Geo">{{Cite web |last=Kiger |first=Patrick J. |date=June 21, 2012 |title=What is the Wow! signal? |url=http://channel.nationalgeographic.com/chasing-ufos/articles/what-is-the-wow-signal/ |url-status=dead |archive-url=https://web.archive.org/web/20150313204253/http://channel.nationalgeographic.com/chasing-ufos/articles/what-is-the-wow-signal/ |archive-date=March 13, 2015 |access-date=July 2, 2016 |website=National Geographic Channel}}</ref>

In 1973, after completing an extensive [[Ohio Sky Survey|survey of extragalactic radio sources]], Ohio State University assigned the now-defunct [[Ohio State University Radio Observatory]] (nicknamed "Big Ear") to the scientific [[search for extraterrestrial intelligence]] (SETI), in the longest-running program of this kind in history.<ref>{{Cite web |date=August 15, 2005 |title=Big Ear Entered in Guinness Book of Records |url=http://www.bigear.org/guinness.htm |access-date=May 30, 2021 |publisher=Big Ear Radio Observatory}}</ref> The radio telescope was located near the [[Perkins Observatory]] on the campus of [[Ohio Wesleyan University]] in [[Delaware, Ohio]].<ref>{{Cite book |last=Kraus |first=John Daniel |title=Big Ear Two: Listening for Other Worlds |publisher=Cygnus-Quasar |year=1995 |isbn=978-1-882484-12-6 |edition=2nd |location=Powell, OH |page=161}}</ref>

By 1977, Ehman was working at the SETI project as a volunteer; his job involved analyzing by hand large amounts of data processed by an [[IBM 1130]] computer and recorded on [[line printer]] paper. While perusing data collected on August 15 at 22:16&nbsp;[[Eastern Time Zone|EDT]] (02:16&nbsp;[[UTC]]), he spotted a series of values of signal intensity and frequency that left him and his colleagues astonished.<ref name="Nat Geo" />
The event was later documented in technical detail by the observatory's director.<ref name="Kraus">John Kraus, Director, Ohio State Radio Observatory 31, January 1994, [https://www.nrao.edu/archives/files/original/2ec6ba346ab16e10a10d09462507beda.pdf "The Tantalizing WOW! Signal"],  Copy of letter to Carl Sagan containing an unpublished paper describing the event.</ref>