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TOPIC: Seti WOW signal
Blobrana


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RE: Seti WOW signal
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Seti Wow! signal

It came on August 15, 1977, the night before Elvis Presley died.
The Ohio radio telescope that picked up the signal was called the Big Ear. At 11.16pm, it recorded a single pulse of radiation that seemed to come from somewhere in the constellation of Sagittarius.
It is now known as the 'Wow! Signal'. That's what Jerry Ehman, the man who spotted it in the computer printout, scrawled in the margin. He had good reason to do so: the characteristics of the signal were exactly what alien-hunters had been told to look out for.
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Blobrana


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WOW! signal
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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. The signal bore expected hallmarks of potential non-terrestrial and non-solar system origin. It lasted for 72 seconds, the full duration Big Ear observed it, but has not been detected again. Much attention has been focused on it in the media when talking about SETI results.
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Astro Dave


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Did Earth receive a signal from E.T. in 1977?
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The two biggest questions we can ask ourselves as a species is where did we come from? and are we alone in the Universe? Surely, in a Universe thats supposed to be infinite, with more stars than there grains of sand on every beach in the world, there are other planets out there populated by intelligent beings.

 

Were now probing the galaxy trying to find them, so far with limited success. But, what if it already happened? What if we picked up a signal from ET in the past. and lost it?  New thoughts suggest we may have cut across a signal purposely, or accidentally, pointing our way. 

On August 15, 1977 something unusual happened. The most famous of all SETI candidate signals (it was even mentioned on The X-Files), the Ohio State University "Wow!" signal was detected by a couple of young researchers setting up their equipment in a rented shed. Over 30 years later, after more than 100 follow-on studies, it remains an intriguing unexplained phenomenon.

The Wow signal's unusual name was given because of both the surprise of the discovery and its socks-knocking strength (60 Janskys in a 10 KHz channel) which is more than 50 thousand times more incoming energy than the minimum signal that would register as a hit for today's Project Phoenix.

The signal, which lasted 72 seconds and came from the direction of Sagittarius, attracted the attention of OhioState astronomer Jerry Ehman, who scrawled "Wow!" in the margin of the print-out. It was, said Ehman, the strangest signal I had ever seen.

 

The signal was near the 21-centimeter line (1420-MHz) of hydrogen, where all radio transmissions are prohibited both on and off the Earth by international agreement.  Unlike Earth bound radio stations, it covered only a narrow spread of frequencies and it definitely came from beyond the distance of the Moon!

 

 The nearest star in the direction the telescope was pointing is 220 light-years away. A source at this distance using a transmitting dish as big as the Arecibo radio telescope (the largest in the world) would require a 2.2 gigawatt transmitter-extraordinarily powerful but not out of the question.

 

 Another possibility is that a much weaker signal from a more remote source (civilisation?) may have experienced gravitational micro-lensing by an intervening star. More than 100 subsequent searches of the same region of sky have failed to recover the signal. However, this is not surprising.

 

A telescope such as the Big Ear listens to only about one millionth of the sky at a time and a similar dish on another planet would broadcast to only about one millionth of the sky. The chance of an alignment between receiver and transmitter, therefore, would only be about one in a trillion. On the other hand, it is possible that many such, similarly strong, intermittent and highly directional signals, are arriving at the Earth every day.

 

The Wow! signal remains unexplained. In my opinion I believe this was the intercepted transmission from another civilization or, we accidentally picked up the interchange between two extraterrestrial ships. Either possibility is mind-boggling. Dave's website: www.davidreneke.com

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Astro Dave
Blobrana


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RE: Seti WOW signal
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A radio signal picked up by a search for extraterrestrial intelligence marks the best candidate yet for "first contact" by aliens.
The signal was traced to a point between the constellations Pisces and Aires, according to New Scientist.
Astronomers who have been scanning the universe for years seeking contact with intelligent life said it stood out as being "unusual".

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Blobrana


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The Seti WOW signal
spacer.gif Huh?
6EQUJ5
On August 15, 1977., SETI received a 1 shot signal that many have described as a WOW signal. It involved a short duration high energy pulse. Each of the first 50 columns of the computer printout shows 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 (10 seconds was used for actual sampling and another approximately 2 seconds was needed for computer program. They used a system of only one alphanumeric character to denote the signal strength. Thus, the "6EQUJ5" code in channel 2 means successive intensities as follows:

6 --> the range 6.0 - 6.999...
E --> the range 14.0 - 14.999...
Q --> the range 26.0 - 26.999...
U --> the range 30.0 - 30.999...
J --> the range 19.0 - 19.999...
5 --> the range 5.0 - 5.999...


The next two

Huh?

groups of numbers on the computer printout (just to the right of the center of the row) are the right ascension and declination converted to epoch 1950. Declination is the angular distance above or below the projection of the earth's equator onto the celestial sky. Its range of values goes from -90 degrees (at the south celestial pole) through zero (on the celestial equator) up to +90 degrees (at the north celestial pole). The Big Ear radio telescope can observe in the 100-degree range of declination from approximately -36 degrees to approximately 64 degrees.
Right ascension is analogous to longitude on the earth's surface. It is measured in either degrees (0 to 360) or in hours, minutes and seconds (00h00m00s up to but not including 24h00m00s). The starting point (0 degrees = 0 hours) is currently in the constellation of Pisces but is moving slowly although constantly (it takes about 26,000 years to make a complete circuit; the major component of this motion is called the "precession of the equinoxes"). Because of this precession and other related but smaller effects, astronomers convert the observed positions at any one instant into one appropriate for a convenient point in time so that locations can be more easily compared.

The epoch (point in time) of 1950 was most commonly used during the middle to late part of the 20th century. Nowadays, the year 2000 is the epoch most likely used.
For the strongest Wow! data point, the epoch 1950 right ascension shown on the computer printout was: 19h17m24s, while the corresponding declination was: -27 degrees and 3 minutes of arc (- 27d03m). Thus puts the source in the direction of the constellation Sagittarius.

Due to some errors in this initial calculation and based upon SETI`s own data a correction to this can be made. In the table below the first column presents the character used for the intensity, the second column shows the original (incorrect) right ascension (epoch 1950) on the computer printout, the third column shows the corrected epoch 1950 R.A. for the end of the integration interval (adding 5m10s to the original R.A.), and the last column shows the corrected epoch 1950 R.A. for the middle of the integration interval (subtracting 5s from the third-column results).

Intensity Original
R.A		 Corrected
R.A.
(End)		 Corrected
R.A.
(Middle)
6 19h16m48s 19h21m58s 19h21m53s
E 19h17m00 19h22m10s 19h22m05s
Q 19h17m12s 19h22m22s 19h22m17s
U 19h17m24s 19h22m34s 19h22m29s
J 19h17m36s 19h22m46s 19h22m41s
5 19h17m48s 19h22m58s 19h22m53s


The computer printout showed 6 significant data points (with intensities ranging from 5 up to 30 sigmas). Each data point represented 10 seconds of data acquisition plus about 2 seconds of computer analysis. Thus, the signal lasted for about 6 * 12 = 72 seconds. The very curious thing about this signal was the fact that we should have seen it twice within a period of about 5 minutes as our two beams sequentially scanned the source, but we only saw one of the beam responses. Thus, if the signal came in the negative horn (the first one to be able to see the source), the signal could not have lasted more than about 2 minutes - 2.5 minutes or we would have seen it also in the second horn (positive horn). Similarly, if the signal came in the positive horn (the second one to be able to see the source), the signal could also not have lasted more than about 2 minutes - 2.5 minutes or we would have seen it also in the first horn (negative horn). This places a limit on the signal duration of 2.5 minutes with either horn.



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