I thought longer exposure times, sky conditions and a stable camera were key in astrophotography. If I'm wrong please correct me, but mounting a camera on an f-18 dosen't sound like good practice.
According to the SWUIS page the 60 fps rate of the camera is used for jitter compensation, so presumably the fast frame rate is quicker than the characteristic timescale of the aircraft motions.
An aside: for the larger aircraft-borne telescopes like the Stratospheric Observatory for Infrared Astronomy (SOFIA) the telescope is "as stable as a mountaintop telescope sitting on a 10 meter cement foundation" according to the FAQs. From that page:
So how do you do this? First, you isolate the telescope from the airplane by mounting it on a spherical pressurized oil bearing. The plane shakes and quakes, but the telescope doesn't feel it. Second, you direct the wind away from the telescope by shaping the side of the airplane so as to deflect it, and install a little deflector fence on the edge of the telescope cavity as well. Third, you stabilize the telescope against sudden motion (wind does get through) by spinning three orthogonal gyroscopes which are rigidly attached to the structure, and fourth, you steer the telescope so as to keep it steady, by tracking a distant star and giving the telescope magnetical nudges to point it toward a fixed direction.
Actually, Fortran still is quite popular in the field of scientific computing. Fortran90/95 and High Performance Fortran that is, definitely NOT Fortran77.
Actually, Fortran77 is still common in astronomy, partly (or mostly?) due to inertia. A lot of code is written in old Fortran, such as the NRAO Astronomical Image Processing System (AIPS).
During my degree we were taught Fortran90, but during my Ph.D. so much of the old code was Fortran77, and so many of the people you'd work with still used it, that many people ended up writing Fortran77 anyway. Of course, I'm not saying that's a good thing, that's just how it was:-)
It's starting to change, though... the new AIPS++ is written in C++, and I haven't written any Fortran for ages.
Is this perhaps the same thing as stochastic resonance? I remember reading about it once; it relies on the idea that by adding white noise to a system you can push its behaviour over some detection threshold, and thus convey the signal better, even though you're actually adding noise. Quite interestingly counter-intuitive at first!
From the linked site above:
In fact, there is an optimal amount of noise for doing this: too little noise and the signal doesn't get through, too much noise and the signal gets swamped.
The Amulet 3 runs at 120 MHz and consumes very little power. Most of all its asynchronous so when you dont have mych processing to do it just sits there consuming "no" power.
When you say 120 MHz do you mean that it has the equivalent performance of a 120 MHz ARM? I'd thought that an asynchronous chip didn't have a clock speed as such.
Partiview (Particle View) is a software package that allows one to navigate through three dimensional data sets. These data sets are not limited to astronomical data, but can be particle data of any type. Partiview is also able to display 2-D images as well as play prerecorded flight paths.
So, I'm not sure how you can call it "universe-simulation software" - it's visualisation software for 3-d data sets, which don't even have to be astronomical in nature. It doesn't actually do any simulation of the physical processes in the universe, as far as I can see.
That's not to belittle it - I find being able to visualise data is one of the most important aspects of research.
The article doesn't say how the nebula was observed, but it's entirely possible it was not using visible light at all but IR, UV, XRAY, whatever (I'm no astronomy expert, but I know they don't always limit themselves to the visible spectrum).
You're right. It actually mentions that the work was done with the Very Long Baseline Array (VLBA) which is a radio telescope.
Linking several together gives you a theoretical mirror many hundereds of miles wide.
Whilst you can do this at radio wavelengths, and have baselines (the separation between individual telescopes) the size of continents as with the VLBA, it is more difficult at optical wavelengths. This is essentially because the much shorter wavelengths make for much tighter tolerances in combining the signals. As far as I know, the current state of the art gives separations of only about 100 metres, rather than miles. See for example COAST and Optical Long Baseline Interferometry News.
Other solution: double up on observations. Different recievers can be attached to a telescope. IR, ultra-violet and visible can be observed at the same time.
Not easily: much of the UV window is very strongly absorbed by the atmosphere, so you can't use it from ground-based telescopes anyway and have to use spacecraft. It's also not so easy to observe two wavelengths at once: you need a lot of complicated optics, and you don't want to waste any of those precious photons. In addition, if the wavelengths are very different, you could have very different design requirements on the rest of the telescope.
So why not double up one projects that are located in the same space in the sky.
They'd have to be really close in the sky. It works for some projects where you're looking at a sample of objects in a patch of sky, like the Hubble Deep Field. However, for many instruments on telescopes like the Keck and Subaru, the field of view is less than 30 arcminutes, which is only the angular diameter of the full moon. Also, the instrument and observing mode you use are strongly dependent on exactly what sort of object you are investigating, and how, and may not be suitable for anything else that happens to be in the field of view.
Also, with image enhancement, you can look at a wider section of sky and view multiple objects, while using computers to examen your specific project.
Image processing and general number-crunching are essential to astronomers already, in order to transform raw data into a final image ("data reduction"). I spent the majority of my Ph.D. working on ways to process a particular type of data, so we're already doing what we can.:-)
Essentially, research-class telescopes are all oversubscribed, and so people tend to make whatever optimisations they can already.
In the context of athmospheric interference, isn't the real benefit of VLA that it becomes possible to see the equally fine details on longer wavelengths? Normally the frequency and resolution are inversely proportional, but I'd expect the athmosphere to impose a limit on the resolution independant of wavelength.
Once you get to radio wavelengths, things are quite different from in the optical; for example, radio telescopes at longer wavelengths can often see through cloud. The limiting factor is the diffraction due to the maximum size of the telescope (or radio interference of human origin) rather than the seeing.
You're right, though, that as we go to the much longer radio wavelengths from the optical, we need much larger telescopes in order to keep the same angular resolution.
I hope the above is reasonably accurate... it's late at night here!
Maybe I'm being trolled:-), but this isn't the same thing as SETI@home , just because the VLA is a radio telescope.
Radio astronomy lets us study objects like supernova remnants and the interstellar medium (and hence star-birth and star-death), or active galaxies such as quasars, and the big cosmological questions about the origin of the universe.
The VLA is no more 'looking for aliens with radios' than optical telescopes are 'looking for aliens with flashlights'.
The VLA is an interferometer, which means that the 27 individual dishes are linked to simulate one huge telescope as big as the largest distance between them (up to 36km). This process of 'aperture synthesis' was pioneered at MRAO in Cambridge, UK (where I used to study, hence the plug:-).
Very roughly speaking, you 'fill in' the gaps in your notional huge telescope by having multiple dishes, sometimes by moving them, and also by allowing the Earth to rotate (thus effectively moving the dishes around for you over the course of a day). The larger the separation between the most distant dishes, the finer the resolution. However, you don't have the collecting area of an actual 36-km telescope, which can limit the sensitivity to faint objects.
So, strictly speaking, where the NYT article says:
Even though there is plenty of room here for more antennas, astronomers want to place the new ones some 60 and 150 miles away in southwestern New Mexico. With the wider dispersion, affording deeper views of the heavens, the Very Large Array will be, in effect, a single telescope the size not of a desert plain, but a quarter of a state.
they aren't quite accurate. "Deeper" is usually taken to mean "able to see fainter objects", whereas the longer baselines ("wider dispersion") will actually be allowing the VLA to see finer details instead.
How about instead of opening it they bury it deeper? I suppose there is always the threat of plunderers and what not, but at some level, is an archeologist any better?
I guess that modern archaeologists are probably quite a bit better, even if earlier generations were a bit haphazard in their techniques. These days there are non-invasive techniques like computerised X-ray tomography (CAT scans) or magnetic resonance imaging (MRI) for examining the mummy itself, but I suppose you'd still have to open the sarcophagus.
What was allegedly the first Egyptology site on the web(!) looks like a good starting point for Egyptology resources. They also have some comments on "The Mummy" and "The Mummy Returns":-)
They must still be building it up painstakingly from bits they teleported from somewhere else:-)
Re:Piss-on-the-perr review system
on
Wolframania
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· Score: 2, Insightful
DO you know that in acedimc science you are only percieved as being a good scientis if you have many publications?
That's not a problem with peer-review per se, though. Surely that's more of a problem with the way funding is assessed? If you're rich enough not to worry about funding you could presumably do some work without publishing loads of papers, and then get it peer-reviewed.
Re:Has anyone here ever heard...
on
Wolframania
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· Score: 1
That's fair enough, you're right. I'm not actually stating that he's a crackpot, or that his book's junk. But I'm still naturally wary of something that seems not to have been subject to much of the usual process of scientific research.
What I'm getting at is that some people seem to think that writing for a decade in seclusion and apparently avoiding peer-review is in some sense a good thing. It makes for a good story, but maybe not good science.
The main text of A New Kind of Science (850 pages) names no names at all; the only work attributed to a specific individual is Wolfram's. The notes at the end of the book (another 350 pages in smaller type) do mention names of people, but briefly, grudgingly and often dismissively. [...] The book has no bibliography; the only references listed are Wolfram's own publications.
I'm certainly not saying his book is junk: it could be a work of genius that happens to share some of the hallmarks of crackpot theories. I'd just be personally much happier if he'd written a work of genius that didn't ring those alarm bells.
Still, anything that gets people thinking and talking about science can't be all bad:-)
Re:Has anyone here ever heard...
on
Wolframania
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· Score: 1
Isn't it possible that he's such a unique guy that he doesn't fit any kind of mold you're aware of?
Sure, it's possible. I wouldn't say it's probable, though.
The probability of him being a genius or otherwise given that he's just written a lengthy, self-published non-peer-reviewed book is governed more by the relative numbers of geniuses and non-geniuses than the fact that he's published the book. Anyone with the resources can publish such a book, but that doesn't change the fact that people who think they are geniuses seem to outnumber people who actually are.
You're right, though. The work could be revolutionary. But I'll be more interested once there's been some peer-review by researchers who actually understand this stuff.
Slashdot Mirror
Aha... thanks :-)
But, but, but... how can a design like this possibly reach orbit?! :-)
According to the SWUIS page the 60 fps rate of the camera is used for jitter compensation, so presumably the fast frame rate is quicker than the characteristic timescale of the aircraft motions.
An aside: for the larger aircraft-borne telescopes like the Stratospheric Observatory for Infrared Astronomy (SOFIA) the telescope is "as stable as a mountaintop telescope sitting on a 10 meter cement foundation" according to the FAQs. From that page:
Actually, Fortran77 is still common in astronomy, partly (or mostly?) due to inertia. A lot of code is written in old Fortran, such as the NRAO Astronomical Image Processing System (AIPS).
During my degree we were taught Fortran90, but during my Ph.D. so much of the old code was Fortran77, and so many of the people you'd work with still used it, that many people ended up writing Fortran77 anyway. Of course, I'm not saying that's a good thing, that's just how it was :-)
It's starting to change, though... the new AIPS++ is written in C++, and I haven't written any Fortran for ages.
Is this perhaps the same thing as stochastic resonance ? I remember reading about it once; it relies on the idea that by adding white noise to a system you can push its behaviour over some detection threshold, and thus convey the signal better, even though you're actually adding noise. Quite interestingly counter-intuitive at first!
From the linked site above:
When you say 120 MHz do you mean that it has the equivalent performance of a 120 MHz ARM? I'd thought that an asynchronous chip didn't have a clock speed as such.
From the "What is Partiview?" page:
So, I'm not sure how you can call it "universe-simulation software" - it's visualisation software for 3-d data sets, which don't even have to be astronomical in nature. It doesn't actually do any simulation of the physical processes in the universe, as far as I can see.
That's not to belittle it - I find being able to visualise data is one of the most important aspects of research.
Just don't try to make yourself a breeder reactor! :-)
Yeah, but imagine the latency :-)
The light-travel time to the moon is 1.3 seconds, so things would get a bit sluggish :-(
You're right. It actually mentions that the work was done with the Very Long Baseline Array (VLBA) which is a radio telescope.
Whilst you can do this at radio wavelengths, and have baselines (the separation between individual telescopes) the size of continents as with the VLBA, it is more difficult at optical wavelengths. This is essentially because the much shorter wavelengths make for much tighter tolerances in combining the signals. As far as I know, the current state of the art gives separations of only about 100 metres, rather than miles. See for example COAST and Optical Long Baseline Interferometry News.
Not easily: much of the UV window is very strongly absorbed by the atmosphere, so you can't use it from ground-based telescopes anyway and have to use spacecraft. It's also not so easy to observe two wavelengths at once: you need a lot of complicated optics, and you don't want to waste any of those precious photons. In addition, if the wavelengths are very different, you could have very different design requirements on the rest of the telescope.
They'd have to be really close in the sky. It works for some projects where you're looking at a sample of objects in a patch of sky, like the Hubble Deep Field. However, for many instruments on telescopes like the Keck and Subaru, the field of view is less than 30 arcminutes, which is only the angular diameter of the full moon. Also, the instrument and observing mode you use are strongly dependent on exactly what sort of object you are investigating, and how, and may not be suitable for anything else that happens to be in the field of view.
Image processing and general number-crunching are essential to astronomers already, in order to transform raw data into a final image ("data reduction"). I spent the majority of my Ph.D. working on ways to process a particular type of data, so we're already doing what we can. :-)
Essentially, research-class telescopes are all oversubscribed, and so people tend to make whatever optimisations they can already.
Once you get to radio wavelengths, things are quite different from in the optical; for example, radio telescopes at longer wavelengths can often see through cloud. The limiting factor is the diffraction due to the maximum size of the telescope (or radio interference of human origin) rather than the seeing.
You're right, though, that as we go to the much longer radio wavelengths from the optical, we need much larger telescopes in order to keep the same angular resolution.
I hope the above is reasonably accurate... it's late at night here!
Maybe I'm being trolled :-), but this isn't the same thing as SETI@home , just because the VLA is a radio telescope.
Radio astronomy lets us study objects like supernova remnants and the interstellar medium (and hence star-birth and star-death), or active galaxies such as quasars, and the big cosmological questions about the origin of the universe.
The VLA is no more 'looking for aliens with radios' than optical telescopes are 'looking for aliens with flashlights'.
The VLA is an interferometer, which means that the 27 individual dishes are linked to simulate one huge telescope as big as the largest distance between them (up to 36km). This process of 'aperture synthesis' was pioneered at MRAO in Cambridge, UK (where I used to study, hence the plug :-).
Very roughly speaking, you 'fill in' the gaps in your notional huge telescope by having multiple dishes, sometimes by moving them, and also by allowing the Earth to rotate (thus effectively moving the dishes around for you over the course of a day). The larger the separation between the most distant dishes, the finer the resolution. However, you don't have the collecting area of an actual 36-km telescope, which can limit the sensitivity to faint objects.
So, strictly speaking, where the NYT article says:
they aren't quite accurate. "Deeper" is usually taken to mean "able to see fainter objects", whereas the longer baselines ("wider dispersion") will actually be allowing the VLA to see finer details instead.
As The Register point out, it's a rather old version of the JVM, and Sun are arguing that it isn't actually Java at all.
For a photon, the energy is Planck's constant multiplied by the frequency. There isn't a speed of light term in there, so you're out by a factor of c.
I guess that modern archaeologists are probably quite a bit better, even if earlier generations were a bit haphazard in their techniques. These days there are non-invasive techniques like computerised X-ray tomography (CAT scans) or magnetic resonance imaging (MRI) for examining the mummy itself, but I suppose you'd still have to open the sarcophagus.
What was allegedly the first Egyptology site on the web(!) looks like a good starting point for Egyptology resources. They also have some comments on "The Mummy" and "The Mummy Returns" :-)
They must still be building it up painstakingly from bits they teleported from somewhere else :-)
That's not a problem with peer-review per se, though. Surely that's more of a problem with the way funding is assessed? If you're rich enough not to worry about funding you could presumably do some work without publishing loads of papers, and then get it peer-reviewed.
That's fair enough, you're right. I'm not actually stating that he's a crackpot, or that his book's junk. But I'm still naturally wary of something that seems not to have been subject to much of the usual process of scientific research.
What I'm getting at is that some people seem to think that writing for a decade in seclusion and apparently avoiding peer-review is in some sense a good thing. It makes for a good story, but maybe not good science.
I've read the concerns at the end of one review:
I'm certainly not saying his book is junk: it could be a work of genius that happens to share some of the hallmarks of crackpot theories. I'd just be personally much happier if he'd written a work of genius that didn't ring those alarm bells.
Still, anything that gets people thinking and talking about science can't be all bad :-)
Sure, it's possible. I wouldn't say it's probable, though.
The probability of him being a genius or otherwise given that he's just written a lengthy, self-published non-peer-reviewed book is governed more by the relative numbers of geniuses and non-geniuses than the fact that he's published the book. Anyone with the resources can publish such a book, but that doesn't change the fact that people who think they are geniuses seem to outnumber people who actually are.
You're right, though. The work could be revolutionary. But I'll be more interested once there's been some peer-review by researchers who actually understand this stuff.
The Post Office? Don't you mean Consignia? No, wait... now it's the Royal Mail. No, wait... :-)
Ah, the wonders of rebranding!
And if you're using www.faxyourmp.com please see what they say about not sending form letters.