I work for the Joint Astronomy Centre and did some of the work in putting those images together. If I remember correctly, I made the JPEGs from the PNGs with ImageMagick's "convert" tool. ImageMagick does seem to support JP2, but I don't know how much it is in general use (I haven't tried it myself) so I usually go for normal JPEGs in order to make sure as many people as possible can view the images.
You're quite right that we don't use supplemental oxygen when up at the telescopes.
However, one difference that I would point out is that usually people climbing mountains such as Mount Rainier (I presume) and certainly Everest will take quite some time to trek up to these kinds of altitudes. With Mauna Kea, you can in principle get from the sea-level town of Hilo to the nearly 14,000-foot summit in a couple of hours if you don't stop to acclimatize. This is, however, an extremely bad idea! People spend acclimatization time at the 9,000-ft level.
The fact that one gets to these kinds of altitudes in a comparatively short time makes the situation slightly different from that of climbers, as far as I understand it.
Your point still stands, though... the telescope control rooms do not have enriched levels of oxygen.
And I was just about to buy one of these cameras:(
So, can anyone suggest some webcams which are well supported by Linux? I'd taken a look at several drivers, but the PWC/PWCX ones seemed to be the best.
With some of the others it seemed to be a lottery whether you'd be able to get a webcam with a compatible chipset (no matter what model number the manufacturer might use on the box).
You're quite right. If you have a telescope of diameter d, looking at a target a distance D away, with light of wavelength l, then the smallest features you can detect are roughly of size Dl/d. So, if the moon is about 4E8 m away, and you're using a 10 m telescope with wavelength of light about 500E-9 m, this works out to roughly 20m. This is far too large to detect things like footprints.
The Hubble Space Telescope has only about a 2m diameter mirror, so you would have roughly a factor of five worse resolution than a 10m ground-based telescope. These are diffraction limits, assuming no atmospheric effects.
It may be feasible to detect an extended shadow of the lander with a large ground-based telescope such as Keck or the VLT. I'm not sure whether it's really possible, but I have heard some people claim this.
Actually I have an exceptional understanding of physics. If you want a more rigorous analysis, then assumuing negligible energy loss to heat, and assuming an isolated piezo crystal (in a vacuum), then yes, 1 watt of sound energy will produce 1 watt of electricity.
"1 watt of sound energy"? Does your exceptional understanding of physics extend to the difference between power and energy?:-)
It would be difficult. I think you're talking about interferometry. This was originally developed for radio telescopes, and is harder to do at shorter wavelengths. The Submillimeter Array, working at the shorter submm wavelengths, has just opened on Mauna Kea, although some work has already been done with linking the James Clerk Maxwell Telescope and the Caltech Submillimeter Observatory. At optical wavelengths it gets harder still. An example is the Cambridge Optical Aperture Synthesis Telescope (COAST). There's also the proposed `Ohana project.
A major problem is that you have to preserve the phase information of the light when you combine the signals from the telescopes, so you can't just record images with a CCD (which only gets you the intensity) and then try to handle the rest of it in software.
Essentially this means that you'd have to combine light from the telescopes in real time and keep the path lengths between them accurate to a small fraction of the wavelength you're measuring. You can do this "off-line" at radio frequencies, for example with the Very Long Baseline Array (VLBA) but not at optical frequencies.
So, in summary, the Internet lets amateur observers collaborate in various ways. However, combining their optical telescopes to get the resolving power of a larger telescope (the size of the distributed collection of individual telescopes) through optical interferometry is not one of them.
What about when you want to apply your own styles, layout, or formatting to the output? I've always found that rather tricky in docbook. Do you have any recommendations for where to start? (I've been using the simple docbook2pdf and docbook2html)
There's more technical information about the system on the eSTAR Project home page, including screenshots and more specific details about the software.
I agree. In fact, I just emailed emusic with a friendly note saying that (unlike most other people in this story, it seems) I wasn't going to cancel my subscription immediately, and I didn't hate them.
Instead, I made a few suggestions that would really make the changes easier to stomach for me, such as being able to carry over one month's worth of download credits, using the improved funding to get more labels, and making whole albums cost slightly fewer credits.
I'm going to see how I do under the new pricing structure, and obviously if it turns out not to be any good for me I'll cancel it then.
I figured that if it was going to make any difference at all, it would be better to tell emusic this rather than just post here!
My point of view, should that interest you, is this: except for a couple of very rare exceptions, every target the HST looks at is chosen after a brutal (trust me,
brutal) review process. The HST costs an enormous of money to run, and they have lived up to that in terms of published peer-reviewed output per observation. So now if they kick in a few thousand extra bucks to take the science images, combine them with a little (not much, mind) artistic license, and release it to the public (who are, after all, paying for it) -- more power to them! Astronomy is one of those rare disciplines where the the excitement of cutting edge science can still be brought to the casual reader - if nothing else, as "Ooh, look, a pretty picture!" I think that is well worth it, as long as they aren't being scientifically dishonest.
Hear, hear. You also beat me to it with responses to the other points:-)
These images are not "doctored", at least not in the way you imply.
You are correct that they are composed from a set of single wavelength images (well, strictly, each individual image has a certain fairly narrow wavelength range defined by a filter). If you're viewing this on a three-colour RGB rather than monochrome display, that's not such a bad way of getting a quick look at three observations in one.
The colours are so vibrant you have to assume they're retouched, and the stars in the background were
added.
Why do you "have to assume they're retouched"? To be fair, if you're putting together an RGB image from three individual images, you will need to make some decision about the scaling for each channel. Also, the caption says that the stars are from an image of stars in the same field, also taken with Hubble. That seems fair enough for a composite image like this.
In addition many of the stars have
lens flares which would destroy any scientific value they had which means the lens flares were Photoshopped in afterward!
No. They are not lens flares, and they are not added for effect.
The artefacts you can see around the brighter stars are diffraction patterns, probably caused by the support structures for the secondary mirror (note: Hubble uses mirrors rather than lenses for its optics anyway). You will see them in many telescope images. You're quite right that the stars do not have that shape, but they are an unavoidable artefact of the observation process. They can be inconvenient, but they do not necessarily "destroy any scientific value".
Whilst I would always go to the original data (images of which are available) to do actual analysis for research purposes, I can also appreciate the aesthetic qualities of one of these "public outreach" images.
I don't want to look at cute picture. I want to see the real one, in false color if the picture show something not in the visible spectrum with a scale saying what's the meaning of each color.
No, the picture hasn't been "forged".
You're correct that the image was constructed from specific wavelengths with certain colours applied. Try going directly to the Hubble Heritage pages for this image. If you read the caption for the image you'll see:
The Hubble Heritage image of N 49 is a color representation of data taken in July 2000, with Hubble's Wide Field Planetary Camera 2. Color filters were used to sample light emitted by sulfur ([S II]), oxygen ([O III]), and hydrogen (H-alpha). The color image has been superimposed on a black-and-white image of stars in the same field also taken with Hubble.
The fast facts will tell you the exact filters used:
The numbers tell you the wavelengths in nanometres. They have possibly assigned red, green, and blue in the same wavelength order, in which case red=sulphur, green=H-alpha, and blue=oxygen.
If you really don't want to look at "cute pictures", don't look at the public outreach images. Take a closer look the original images.
True, those objects block our view at optical wavelengths, but they can be transparent (well, optically thin) at submillimetre wavelengths. I work for the James Clerk Maxwell Telescope, which is the world's largest single-dish submillimetre-wave telescope. The JCMT has, for example, seen into the cores of the famous pillars in the Eagle Nebula.
So could you get around this for the Massive Attack CD? Did you manage to rip the tracks in the end? I'm trying to decide whether to buy the album, but I also listen to my music on a computer at work.
I find it disappointing the way so many people deny that Saddam Hussein is responsible not only for direct attacks on America, but also...
I know what you mean about the atrocities in his own country, but as regards the part above, please could you clarify for which direct attacks on America Saddam Hussein is responsible? I'd be particularly interested to hear about ones in the past decade or so since the "first Gulf War".
Slashdot Mirror
The software you saw at the Hayden might have been something to do with Partiview:
Which instances did you have in mind? Are you including Chandrasekhar, or Martin Ryle?
I work for the Joint Astronomy Centre and did some of the work in putting those images together. If I remember correctly, I made the JPEGs from the PNGs with ImageMagick's "convert" tool. ImageMagick does seem to support JP2, but I don't know how much it is in general use (I haven't tried it myself) so I usually go for normal JPEGs in order to make sure as many people as possible can view the images.
You're quite right that we don't use supplemental oxygen when up at the telescopes.
However, one difference that I would point out is that usually people climbing mountains such as Mount Rainier (I presume) and certainly Everest will take quite some time to trek up to these kinds of altitudes. With Mauna Kea, you can in principle get from the sea-level town of Hilo to the nearly 14,000-foot summit in a couple of hours if you don't stop to acclimatize. This is, however, an extremely bad idea! People spend acclimatization time at the 9,000-ft level.
The fact that one gets to these kinds of altitudes in a comparatively short time makes the situation slightly different from that of climbers, as far as I understand it.
Your point still stands, though... the telescope control rooms do not have enriched levels of oxygen.
There's a thread on the Gentoo forums about this. Apparently it is to do with TCP/IP window resizing. There's also a LWN article.
And I was just about to buy one of these cameras :(
So, can anyone suggest some webcams which are well supported by Linux? I'd taken a look at several drivers, but the PWC/PWCX ones seemed to be the best.
With some of the others it seemed to be a lottery whether you'd be able to get a webcam with a compatible chipset (no matter what model number the manufacturer might use on the box).
You're quite right. If you have a telescope of diameter d, looking at a target a distance D away, with light of wavelength l, then the smallest features you can detect are roughly of size Dl/d. So, if the moon is about 4E8 m away, and you're using a 10 m telescope with wavelength of light about 500E-9 m, this works out to roughly 20m. This is far too large to detect things like footprints.
The Hubble Space Telescope has only about a 2m diameter mirror, so you would have roughly a factor of five worse resolution than a 10m ground-based telescope. These are diffraction limits, assuming no atmospheric effects.
It may be feasible to detect an extended shadow of the lander with a large ground-based telescope such as Keck or the VLT. I'm not sure whether it's really possible, but I have heard some people claim this.
...(following my original reply) ...but, other than that, I did think your original post was funny...
"1 watt of sound energy"? Does your exceptional understanding of physics extend to the difference between power and energy? :-)
It would be difficult. I think you're talking about interferometry. This was originally developed for radio telescopes, and is harder to do at shorter wavelengths. The Submillimeter Array, working at the shorter submm wavelengths, has just opened on Mauna Kea, although some work has already been done with linking the James Clerk Maxwell Telescope and the Caltech Submillimeter Observatory. At optical wavelengths it gets harder still. An example is the Cambridge Optical Aperture Synthesis Telescope (COAST). There's also the proposed `Ohana project.
A major problem is that you have to preserve the phase information of the light when you combine the signals from the telescopes, so you can't just record images with a CCD (which only gets you the intensity) and then try to handle the rest of it in software.
Essentially this means that you'd have to combine light from the telescopes in real time and keep the path lengths between them accurate to a small fraction of the wavelength you're measuring. You can do this "off-line" at radio frequencies, for example with the Very Long Baseline Array (VLBA) but not at optical frequencies.
So, in summary, the Internet lets amateur observers collaborate in various ways. However, combining their optical telescopes to get the resolving power of a larger telescope (the size of the distributed collection of individual telescopes) through optical interferometry is not one of them.
Thanks for the link. I'll check it out.
What about when you want to apply your own styles, layout, or formatting to the output? I've always found that rather tricky in docbook. Do you have any recommendations for where to start? (I've been using the simple docbook2pdf and docbook2html)
There's more technical information about the system on the eSTAR Project home page, including screenshots and more specific details about the software.
I agree. In fact, I just emailed emusic with a friendly note saying that (unlike most other people in this story, it seems) I wasn't going to cancel my subscription immediately, and I didn't hate them.
Instead, I made a few suggestions that would really make the changes easier to stomach for me, such as being able to carry over one month's worth of download credits, using the improved funding to get more labels, and making whole albums cost slightly fewer credits.
I'm going to see how I do under the new pricing structure, and obviously if it turns out not to be any good for me I'll cancel it then.
I figured that if it was going to make any difference at all, it would be better to tell emusic this rather than just post here!
Hear, hear. You also beat me to it with responses to the other points :-)
These images are not "doctored", at least not in the way you imply.
You are correct that they are composed from a set of single wavelength images (well, strictly, each individual image has a certain fairly narrow wavelength range defined by a filter). If you're viewing this on a three-colour RGB rather than monochrome display, that's not such a bad way of getting a quick look at three observations in one.
Why do you "have to assume they're retouched"? To be fair, if you're putting together an RGB image from three individual images, you will need to make some decision about the scaling for each channel. Also, the caption says that the stars are from an image of stars in the same field, also taken with Hubble. That seems fair enough for a composite image like this.
No. They are not lens flares, and they are not added for effect.
The artefacts you can see around the brighter stars are diffraction patterns, probably caused by the support structures for the secondary mirror (note: Hubble uses mirrors rather than lenses for its optics anyway). You will see them in many telescope images. You're quite right that the stars do not have that shape, but they are an unavoidable artefact of the observation process. They can be inconvenient, but they do not necessarily "destroy any scientific value".
Whilst I would always go to the original data (images of which are available) to do actual analysis for research purposes, I can also appreciate the aesthetic qualities of one of these "public outreach" images.
No, the picture hasn't been "forged".
You're correct that the image was constructed from specific wavelengths with certain colours applied. Try going directly to the Hubble Heritage pages for this image. If you read the caption for the image you'll see:
The fast facts will tell you the exact filters used:
The numbers tell you the wavelengths in nanometres. They have possibly assigned red, green, and blue in the same wavelength order, in which case red=sulphur, green=H-alpha, and blue=oxygen.
If you really don't want to look at "cute pictures", don't look at the public outreach images. Take a closer look the original images.
Hope this helps.
True, those objects block our view at optical wavelengths, but they can be transparent (well, optically thin) at submillimetre wavelengths. I work for the James Clerk Maxwell Telescope, which is the world's largest single-dish submillimetre-wave telescope. The JCMT has, for example, seen into the cores of the famous pillars in the Eagle Nebula.
The parent comment shouldn't have been modded 'Offtopic': it's a printing and bone reference, people. :-)
But it is still also a city, so the original poster has a point, even if he is being buttock-clenchingly pedantic! The www.la website says:
where from what you're saying they should strictly have said "...first and only city that is not also a country..." :-)
So could you get around this for the Massive Attack CD? Did you manage to rip the tracks in the end? I'm trying to decide whether to buy the album, but I also listen to my music on a computer at work.
I'm confused... did you mean to write "Stalin", or "Stallman"?
I know what you mean about the atrocities in his own country, but as regards the part above, please could you clarify for which direct attacks on America Saddam Hussein is responsible? I'd be particularly interested to hear about ones in the past decade or so since the "first Gulf War".
How about:
Actually I think I defer to some of the other replies that point to 'biblion' as the root here, which presumably comes originally from 'biblos'.