[BRIEF NOTE] On the Wow! Signal
Feb. 3rd, 2012 09:12 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
rfmcdonaldThe Wow! signal is fascinating.
Why "Wow?" Well, the signal's characteristics matched the hypothesized characteristics of a signal by a technological civilization pretty well.
The signal seemed to come from a point in interstellar space within the constellation Sagittarius, far from any bright stars that would have been plausible transmission sources.
Centauri Dreams and the Planetary Society Blog both review--the Planetary Society Blog's Amir Alexander in great and enlightening detail--a new book, Robert Gray's The Elusive Wow: Searching for Extraterrestrial Intelligence, that describes Gray's efforts to track down the signal. Gray claims to have found some unusual radio signals coming from the hypothesized vicinity of the Wow! signal's origins, though nothing obvious.
I wonder. And you?
The Wow! signal was a strong narrowband radio signal detected by Dr. Jerry R. Ehman on August 15, 1977, while working on a SETI project at the Big Ear radio telescope of The Ohio State University then located at Ohio Wesleyan University's Perkins Observatory, Delaware, Ohio. The signal bore expected hallmarks of potential non-terrestrial and non-solar system origin. It lasted for the full 72-second duration that Big Ear observed it, but has not been detected again. The signal has been the subject of significant media attention.
Amazed at how closely the signal matched the expected signature of an interstellar signal in the antenna used, Ehman circled the signal on the computer printout and wrote the comment "Wow!" on its side. This comment became the name of the signal.
Why "Wow?" Well, the signal's characteristics matched the hypothesized characteristics of a signal by a technological civilization pretty well.
The circled alphanumeric code 6EQUJ5 describes the intensity variation of the signal. A space denotes an intensity between 0 and 1, the numbers 1 to 9 denote the correspondingly numbered intensities (from 1.000 to 10.000), and intensities of 10.0 and above are denoted by a letter ('A' corresponds to intensities between 10.0 and 11.0, 'B' to 11.0 to 12.0, etc.). The value 'U' (an intensity between 30.0 and 31.0) was the highest detected by the telescope, on a linear scale it was over 30 times louder than normal deep space. The intensity in this case is the unitless signal-to-noise ratio, where noise was averaged for that band over the previous few minutes.
Two different values for its frequency have been given: 1420.356 MHz (J. D. Kraus) and 1420.4556 MHz (J. R. Ehman). The frequency 1420 is significant for SETI searchers because, it is reasoned, hydrogen is the most common element in the universe, and hydrogen resonates at about 1420 MHz, thus extraterrestrials might use that frequency on which to transmit a strong signal. The frequency of the Wow! signal matches very closely with the hydrogen line, which is at 1420.40575177 MHz. It is worth noting that the two different values given for the frequency of the Wow! signal (1420.356 MHz and 1420.4556 MHz) are the same distance apart to the hydrogen line - the first being about 0.0498 MHz less than the hydrogen line, and the second being about 0.0498 MHz more than the hydrogen line. The bandwidth of the signal is less than 10 kHz (each column on the printout corresponds to a 10 kHz-wide channel; the signal is only present in one column).
The signal seemed to come from a point in interstellar space within the constellation Sagittarius, far from any bright stars that would have been plausible transmission sources.
Centauri Dreams and the Planetary Society Blog both review--the Planetary Society Blog's Amir Alexander in great and enlightening detail--a new book, Robert Gray's The Elusive Wow: Searching for Extraterrestrial Intelligence, that describes Gray's efforts to track down the signal. Gray claims to have found some unusual radio signals coming from the hypothesized vicinity of the Wow! signal's origins, though nothing obvious.
I wonder. And you?
