"On This Day" In Engineering History Blog

"On This Day" In Engineering History

Tune in to find out about significant engineering events that took place "on this day".

Previous in Blog: August 2, 1939 – Einstein Warns a President   Next in Blog: August 21, 1957 - The 50th Anniversary of the R-7 Rocket
Close
Close
Close
2 comments

August 15, 1977 - Did Ohio State Hear E.T.?

Posted August 15, 2007 4:53 PM by Steve Melito

Thirty years ago today, a volunteer at the Big Ear Radio Observatory at Ohio State University (OSU) monitored a strong signal from outer space. Was this Earth's first encounter with intelligent, extraterrestrial life? Jerry Ehman, the OSU volunteer who scrawled "Wow!" on the original computer printout, was ecstatic about that very possibility. "I mean, without thinking, I wrote 'Wow!'", Ehman later recalled. "It was the most significant thing we had seen."

The "Wow! Signal" that Ehman detected on August 15, 1977 captured the imaginations of astronomers around the world. Students of the night skies aimed their telescopes at the point where the signal seemed to originate, but were greeted with silence. Their failure to find anything made many people, including Ehman, skeptical. "Even if it were intelligent beings sending a signal, they'd do it far more than once," the astronomer later told the Cleveland Plain Dealer. "We should have seen it again when we looked for it 50 times. Something suggests it was an Earth-bound signal that simply got reflected off a piece of space debris."

What About the Code on the Printout?

The photo at the top-left depicts the computer printout with Jerry Ehman's handwrittten comment ("Wow!") and six circled characters (6EQUJ5) that are aligned vertically. So what does this code mean?

Each of the first 50 columns indicates the successive values of intensity (or power) received from the Big Ear radio telescope in each channel (10 kHz wide) in successive 12-second intervals. Ten seconds were used for sampling and another two seconds were used for computer processing.

To conserve space on the printout, Ehman used a coding method of one alphanumeric character for each intensity. The observatory's computer was programmed to keep a continuously-updated account for each channel of a baseline value and a root mean square (RMS) value.

After the baseline value was subtracted, the actual intensity was divided by the RMS value to obtain a scaled value. Because there was room for only one character on the printout, Ehman used only the integer value of this scaled intensity for values ranging from 0 to 9.999.

The value of zero printed as a blank (space). Value of 1, 2, 3, 4, 5, 6, 7, 8, and 9 were printed directly. For scaled intensities from 10 to 35, capital letters were used. For example, a truncated value of 10 printed as an "A" while a truncated value of 11 printed as a "B". When the scaled intensity exceeded 36, the program would start over again at zero. So, a truncated value of 38 printed as that of 38 - 35 = 3 (i.e., 3).

The 6EQUJ5 code in channel 2 indicates successive intensities as follows:

6 = 6.0 - 6.999
E = 14.0 - 14.999
Q = 26.0 - 26.999
U = 30.0 - 30.999
J = 19.0 - 19.999
5 = 5.0 - 5.999

The value "U" (a range of 30.0 - 30.999) was the largest value that Ehman and another volunteer, Bob Dixon, had ever seen. Because the intensity never exceeded 31.0, there was no rollover. "It would have been easy to spot in a sequence of 6 or 7 numbers," Ehman explained, "that should follow the antenna pattern of the telescope."

Although the six successive values in channel 2 fit the antenna pattern of Big Ear, Jerry Ehman also completed a correlation analysis of the six data points with the mathematical functions: (1) gaussian = normal curve; and (2)(sin(x)/x)^2. Again, the data fit each of those two functions, with correlation coefficients of over 0.99.

In addition, Ehman fit the data to each of the two actual antenna patterns of the two horns, using the moderately strong radio source OY372. Again, the correlation coefficients were over 0.99. Unfortunately, there was not enough difference between the two correlation coefficients to determine which horn the "Wow! signal" was received in.

Resources:

http://www.wired.com/science/discoveries/news/2007/08/dayintech_0815

http://www.bigear.org/wow.htm

http://www.bigear.org/6equj5.htm

Reply

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Power-User

Join Date: Aug 2007
Location: Knoxville Tenn, Lake Helen, FL
Posts: 191
#1

Re: August 15, 1977 - Did Ohio State Hear E.T.?

08/16/2007 2:06 PM

"Maybe" on of our own satellites or one of our own spacecraft (ie apollo program) just happened to cross the beam of the ohio recievers and at the same time was broadcasting? If a signal were strong enough it could "bleed" over into other frequency spectrums which "might" account for the two horns both seeming to hear the same signal?

__________________
Peace begets Synergy which begets Progress!
Reply
Anonymous Poster
#2
In reply to #1

Re: August 15, 1977 - Did Ohio State Hear E.T.?

01/21/2008 3:17 AM

is there any sound clip on it?

Reply
Reply to Blog Entry 2 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Previous in Blog: August 2, 1939 – Einstein Warns a President   Next in Blog: August 21, 1957 - The 50th Anniversary of the R-7 Rocket

Advertisement