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Worlds Largest Telescope?
AndersBrownworth writes "With a unique take on "Distributed Computing", the PhotonStar Project aims to search for laser transmissions from extra terrestrial life by harnessing amateur astronomers who have an optical telescope with a laser detector, a GPS and a computer with a net connection. I think it would be interesting to get a large number of computer controlled optical telescopes together that have GPS and CCD capabilities and build the world's largest optical telescope. The concept wouldn't be much different from New Mexico's VLA Radio Telescope. Given the falling prices of computer controlled optical telescopes, a project like this might not be far off."
Can you imagine the possibility for website of collected peeping tom images?
DO NOT LOOK INTO LASER BEAM (from an alien race) WITH REMAINING EYE!
Ed Wedig
Graphic design services
docbrown.net
Actually, it would be. The VLA works because all the signals are brought together and correlated - they are carefully time synced (to the nanosecond) and then combined.
The same trick in the optical domain is called interferometry, and requires that the actual LIGHT from each 'scope be brought together - you need not only the brightness (which a CCD would record), but the phase and polarization of the signal (which a CCD won't record).
So you cannot use an array of 'scopes world-wide to create a virtual array.
What you can do, and what optical SETI is all about, is to have each scope looking at a different star (or star field) at each time.
In a way, comparing the two is like comparing a 64-way NUMA cluster to a Beowulf cluster - one will work well with one big program of many threads sharing data (NUMA/interferometry), and one will work well with many small independent programs (Beowulf/optical SETI).
www.eFax.com are spammers
So you cannot use an array of 'scopes world-wide to create a virtual array.
If you had read the linked article then you would know that they are proposing to look for pulsed signals from a targeted star. Statistical analysis of data from thousands of scopes does improve performance on this task.
And had you READ my POST, you would have seen that I was not addressing the article, but rather the poster's wild-assed and incorrect statement about making a VLA from all those amateur scopes.
www.eFax.com are spammers
in Australia.
:)
Site are here, here, and here.
Some technical details are here.
From the later,
The antenna has "...a proposed collecting area at low frequencies (150 MHz to 1.5 GHz) of roughly 1 km2 (or 106 m2) - the equivalent of more than one hundred dishes of 100 m diameter. In contrast, the largest and most sensitive existing array has a physical area approximately one hundred times smaller than this."
That's pretty big.
I know that the idea of trying to use this as a vlt type thing is kind of moot(not an astronomer just a hobbyist mind you) but it does provide some interesting possibilities.
Huge catalogs could be created and used for comparisons that could lead to additional comet discoveries for example. If the system is using gps it is possible to have some time sync though not to the hyper accurate clocks that vlts use. I think it would still be useful information, especially to the amateur astronomy crowd.
I wonder what mindpixel will have to say about this.
Prospecting Stinks. Stop Wasting Time on Cold Calling.
The project requires you know the position of your telescope to within 1 foot in all lattitude, longitude, and altitude. (Timing is critical and you need to know if a pulse arrived within a nanosecond of each other. 1 nanosecond is about 1 foot.) Standard GPS gives you somewhere around 15-30 foot accuracy at best. How are they planning on getting the needed positional accuracy if GPS doesn't provide it?
I do remember quite a while ago NASA developing some statistical method of getting extremely accurate GPS positional data from taking masses of GPS data over many weeks (IIRC it was accurate to something like centimeters). Unfortunately it was just a newspaper article, so the details were lacking. Could this be how they plan on getting the accurate positional data? Anyone know more about this?
AccountKiller
Now if we can find out how to compensate for the Earth's spherical shape, we can finally get a good look at those Brazilian Thongs.
This is an interesting method, because it really irons out systematic effects due to the local patch of atmosphere above any one telescope.
The atmospheric turbulence causes 'scintillation' of starlight (a rapid, small variation in stellar brightness), and for the very short exposures they're proposing, it'd be difficult with just one telescope to pull out an ET laser modulated signal from the atmospheric generated scintillation.
Distributed telescopes with accurate positions would pull out a laser signal very easily.
Cute trick.
Dr Fish
What we have here is yet another web page which won't display correctly on most browsers. When will they learn that HTML cna be written to adapt to the pixel width of the browser, isntead of assuming that everybody has the same high-res system that they do? Sheesh.
One telescope looking thru the window and 9999 looking at the walls of the house?! Your request for telescope time is denied!
If we were ants living on a Rubik's cube, differential geometry would be a little more confusing.
Unfortunately the refractive index of the atmosphere is not uniform, and turbulence makes it vary fairly quickly and unpredictably. In other words, the same effect that makes stars twinkle should scatter the arrival times by an amount that I'm guessing is much more than a nanosecond. So distributed small telescopes are not quite the same as a single big telescope after all*.
The second problem is an old one for optical SETI, namely that dust in the plane of the Galaxy limits how far optical light (as opposed to radio) can travel. How much this matters is a matter of debate.
*Interferometers (try to) deal with this (and similar problems) by picking a known pointlike bright source (i.e. a quasar) and adjusting their relative phases to make that object look like a point. It's sort of like focusing a camera. The only way I can think of for distributed pulse detection to deal with random delays is to correlate the signals. That's a lot of CPU work, and more importantly requires the aliens to send a series of pulses so that the telescopes could detect multiple events. Even then, I haven't worked out what the signal to noise would be like.
If we were ants living on a Rubik's cube, differential geometry would be a little more confusing.
P( Amateur Astronomer ) * P( Has Optical Telescope ) * P( Has Lazer Detector ) * P( Has GPS ) * P( Has Computer With Net Connection ) * P( Has Heard of this Project ) * 6 billion people on planet earth = 4
Eat at Joe's.