Explanation: The Five-hundred-meter Aperture Spherical Telescope (FAST) is nestled within a natural basin in China's remote and mountainous southwestern Guizhou province. Nicknamed Tianyan, or the Eye of Heaven, the new radio telescope is seen in this photograph taken near the start of its testing phase of operations on September 25. Designed with an active surface for pointing and focusing, its enormous dish antenna is constructed with 4,450 individual triangular-shaped panels. The 500 meter physical diameter of the dish makes FAST the largest filled, single dish radio telescope on planet Earth. FAST will explore the Universe at radio frequencies, detecting emission from hydrogen gas in the Milky Way and distant galaxies, finding faint galactic and extragalactic pulsars, and searching for potential radio signals from extraterrestrials.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk. — Garrison Keillor
https://en.wikipedia.org/wiki/Contact_(novel) wrote:
<<Contact is a 1985 science fiction novel by Carl Sagan: After graduating from Harvard University, Eleanor "Ellie" Arroway receives a doctorate from Caltech supervised by David Drumlin, a well known radio astronomer. She eventually becomes the director of "Project Argus", a radiotelescope array in New Mexico dedicated to the search for extraterrestrial intelligence (SETI). This puts her at odds with most of the scientific community, including Drumlin who tries to have the funding to SETI cut-off. To his surprise, the project discovers a repeating series of 26 prime numbers coming from the Vega system 25 light years away. Further analysis reveals information in the polarization modulation of the signal. This message is a retransmission of Adolf Hitler's opening speech at the 1936 Summer Olympics in Berlin; the first television signal powerful enough to escape Earth's ionosphere.>>
<<KCPR (at 91.3 MHz FM) is a non-profit freeform college radio station at Cal Poly in San Luis Obispo. KCPR's first broadcast occurred with a small 2-watt transmitter in the Fall of 1968; according to station lore, the first words spoken on-air were, "Is this the damn switch?" not "Christ, are we on the air?" as it is sometimes reported. KCPR was then known as "Burnt Dog Radio," an axiom that is reflected in one of the station's early logo designs that featured the RCA Victor dog. Weird Al Yankovic was a volunteer DJ there when he was an undergraduate architecture student at the university. Yankovic recorded his iconic parody song "My Bologna" in the bathroom that stands across the hall from the station's original location on the second floor of the Journalism Building on the Cal Poly campus.>>
APOD Robot wrote:The 500 meter physical diameter of the dish makes FAST the largest filled, single dish radio telescope on planet Earth.
Sort of. Its optical diameter is about the same as Arecibo's (when the latter is used on-axis). By restricting the FOV of the secondary to 300m, they're able to avoid vignetting when off axis. Also, because the primary is deformable, this scope achieves higher off-axis resolution, since it can be physically off-axis without being optically so.
Chris
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Chris L Peterson
Cloudbait Observatory https://www.cloudbait.com
APOD Robot wrote:
The 500 meter physical diameter of the dish makes FAST the largest filled, single dish radio telescope on planet Earth.
Sort of. Its optical diameter is about the same as Arecibo's (when the latter is used on-axis). By restricting the FOV of the secondary to 300m, they're able to avoid vignetting when off axis. Also, because the primary is deformable, this scope achieves higher off-axis resolution, since it can be physically off-axis without being optically so.
Yes...but the Vega system will be pretty much directly overhead when they receive the Weird signAl in 2018-20.
I like the comment I saw the other day: when they took some of the local Chinese up to see what they had built in the mountains, one of them replied that it looked like a giant iron wok!
Visual_Astronomer wrote:
I like the comment I saw the other day: when they took some of the local Chinese up to see what they had built in the mountains, one of them replied that it looked like a giant iron wok!
<<The main advantage of wok beyond its constructed material is its curved concave shape. The shape produces a small, hot area at the bottom which allows some of the food to be seared by intense heat while using relatively little fuel. The large sloped sides also make it easier for chefs to employ the tossing cooking technique on solid and thick liquid food with less spillage and a greater margin of safety. Curved sides also allows a person to cook without having to "chase the food around the pan" since bite-sized or finely chopped stir-fry ingredients usually tumble back to the center of the wok when agitated. The curve also provides a larger usable cooking surface versus western-styled pots and pans.>>
You are an extraterrestrial... you are overseeing Earth... you are from Light Years away... you really going to use....Radio????? Our radio signals dissipate about 1.5-2 light years out, before it blends in with the background radiation....NOBODY is watching Lucy.... and NOBODY else's Radio signals reach us. I suppose there are higher intensity beams that are sent at a certain local....but is there anybody even there???? With Equipment?? And it still takes the same amount of time... totally useless....
You need another faster method... A Laser still takes years... and has to hit a target. Tachyon pulses? Maybe... but they probably have to have some sort of Tachyon target receiver too...
OH... I got it.....TELEPATHY....SPIRIT TALKING....Yup....Got it....we're good.
Boomer12k wrote:
You are an extraterrestrial... you are overseeing Earth... you are from Light Years away... you really going to use....Radio????? Our radio signals dissipate about 1.5-2 light years out, before it blends in with the background radiation....NOBODY is watching Lucy....
Our radio signals dissipate about 1.5-2 light years out, before it blends in with the background radiation for the resolution of Low-Frequency Array (LOFAR). Double the receiving antenna size/resolution and the signal to noise improves by a factor of 4. (The signal could be further improved by watching all the reruns.)
<<The first episode of "I Love Lucy" was broadcast sometime on October 15, 1951. Given that stars in our galactic neighborhood are separated by about 4 light-years, it's easy to figure that roughly 10 thousand star systems have been exposed to "I Love Lucy" in the past five decades.
This possibility was evidently on the mind of Abraham Loeb at Harvard University, who recently noted in the New Scientist that a radio telescope being built to study distant galaxies might also be able to pick up ET's TV. The so-called Low-Frequency Array (LOFAR), a telescope consisting of 25 thousand tent-shaped antennas spread across Holland and Germany, can be tuned to frequencies under 250 megahertz. This is a spectral range far below what's usually searched by SETI, but it's the band in which much of your local television is broadcast. And maybe theirs, as well.
So how realistic is this? Could LOFAR really pick up "I Love Zork"? To answer that question requires doing some numbers. First, we reverse the situation, just to see if tuning in remote TV makes sense.
Imagine that there are alien couch potatoes 55 light-years away who, bored with their own Fall lineup, have constructed a LOFAR-style antenna in hopes of picking up "I Love Lucy's" debut. Hunky TV transmitters on Earth belch out a few hundred thousand watts of power. That energy is not beamed in all directions equally; most of it is aimed around the horizon (which, of course, is where the audience is). Because of this slight beaming, the effective transmitter power is a bit more: let's say a million watts, to keep the math simple.
OK, how strong is that signal by the time it reaches our putative alien audience at 55 light-years distance? Not very. The megawatt broadcast washes over ET's world with a power density of about 0.3 million million million million millionths of a watt per square meter, which is not exactly a scorching signal. Actually, only about a third of that transmission power is in the "carrier" - the part of the broadcast that's very narrow in frequency and easily detected. So knock that piddling power density down by another factor of three if you want to know the strength of the easily detectable part of the transmission. (Of course, if they only find the carrier, they won't get the picture and sound. But Lucy's jokes might not appeal to aliens anyway.)
Could their LOFAR-style antenna find that carrier, thereby indicating that a program was on the air? Well, engineers have computed that at the frequency of VHF television, LOFAR will have an effective collecting area similar to that of the 305-meter diameter Arecibo antenna in Puerto Rico.
That's big. That's brawny. But not brawny enough. In our SETI experiments at Arecibo, we could find a signal if it were about 0.1 million million million millionths of a watt per square meter. That number, you will notice if you count up the words, is a million times bigger than the "I Love Lucy" carrier at 55 light-years. The aliens' LOFAR would be inadequate to detect the broadcast by a factor of a million, a not entirely negligible amount. Simply stated: LOFAR couldn't hear it.>>
Boomer12k wrote:You are an extraterrestrial... you are overseeing Earth... you are from Light Years away... you really going to use....Radio????? Our radio signals dissipate about 1.5-2 light years out, before it blends in with the background radiation....NOBODY is watching Lucy.... and NOBODY else's Radio signals reach us. I suppose there are higher intensity beams that are sent at a certain local....but is there anybody even there???? With Equipment?? And it still takes the same amount of time... totally useless....
You need another faster method... A Laser still takes years... and has to hit a target. Tachyon pulses? Maybe... but they probably have to have some sort of Tachyon target receiver too...
OH... I got it.....TELEPATHY....SPIRIT TALKING....Yup....Got it....we're good.
:---[===] *
LOL, however Contact is science fiction coupled with 1980's science knowledge (although I'll admit that he should of thought of lasers). Tachyon pulses are sciece fiction inventions of other authors of the time. Maybe he did not want to borrow that. LOL
Boomer12k wrote:You are an extraterrestrial... you are overseeing Earth... you are from Light Years away... you really going to use....Radio????? Our radio signals dissipate about 1.5-2 light years out, before it blends in with the background radiation....NOBODY is watching Lucy.... and NOBODY else's Radio signals reach us. I suppose there are higher intensity beams that are sent at a certain local....but is there anybody even there???? With Equipment?? And it still takes the same amount of time... totally useless....
You need another faster method... A Laser still takes years... and has to hit a target. Tachyon pulses? Maybe... but they probably have to have some sort of Tachyon target receiver too...
OH... I got it.....TELEPATHY....SPIRIT TALKING....Yup....Got it....we're good.
:---[===] *
LOL, however Contact is science fiction coupled with 1980's science knowledge (although I'll admit that he should of thought of lasers). Tachyon pulses are sciece fiction inventions of other authors of the time. Maybe he did not want to borrow that. LOL
Borrowing it could have been construed as being tachy
Sorry to be away so long. Life takes us different ways at times. Anyway, just thought I'd mention. The proper translation of 眼睛的天堂 or Tianyan is "Eye of Paradise." Friends from my college days told me that, in Chinese, they have no word for God so may not have a word that we would translate "heaven" either. They call God "Up King" so Heaven is, no doubt, "Paradise." Just a little factoid I thought somebody might find interesting; not that it matters much.
Five Hundred Meter Aperture Spherical Telescope
