Editing Wow! signal (section)

=== Frequency ===
[[John Kraus]], the director of the observatory, gave a value of {{val|1420.3556|fmt=none|ul=MHz}} in a 1994 summary written for [[Carl Sagan]].<ref name=Kraus/> However, Ehman in 1998 gave a value of {{val|1420.4556|.005|fmt=none|u=MHz}}.<ref name="Big Ear 97">{{Cite web |last=Ehman |first=Jerry R. |date=February 3, 1998 |title=The Big Ear Wow! Signal. What We Know and Don't Know About It After 20 Years |url=http://www.bigear.org/wow20th.htm |access-date=July 2, 2016}}</ref> This is ({{val|50|5|u=kHz}}) above the [[hydrogen line]] value (with no [[Redshift|red-]] or blue-shift) of {{val|1420.4058|fmt=none|u=MHz}}. If due to blue-shift, it would correspond to the source moving about {{cvt|10|km/s}} towards Earth.

[[File:Wow signal spectrogram.svg|thumb|A [[heat map]] of the computer printout, giving a [[spectrogram]] of the beam; the Wow! signal appears as a bright spot in the lower left.]]
An explanation of the difference between Ehman's value and Kraus's can be found in Ehman's paper. The first [[local oscillator]] in the telescope's radio receiver was specified to a frequency value of {{val|1450.4056|fmt=none|u=MHz}}. However, the university's purchasing department made a [[typographical error]] in the order form, instead obtaining an oscillator with frequency {{val|1450.5056|fmt=none|u=MHz}} (i.e., {{val|0.1|u=MHz}} higher than desired). The software used in the experiment was then written to adjust for this error. When Ehman computed the frequency of the Wow! signal, he took this error into account.{{citation needed|date=August 2020}}