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What is the highest radio frequency used for radio astronomy?
Hi:
What is the highest radio frequency used for radio astronomy? According to the link below, it is 3438 GHz: http://books.nap.edu/openbook.php?re...=11719&page=11 Is 3438 GHz the highest radio frequency used for radio astronomy? Thanks, Radium |
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What is the highest radio frequency used for radio astronomy?
Radium wrote:
Hi: What is the highest radio frequency used for radio astronomy? According to the link below, it is 3438 GHz: http://books.nap.edu/openbook.php?re...=11719&page=11 Is 3438 GHz the highest radio frequency used for radio astronomy? If you read on a little farther you'll find 'blurring the distinction between radio astronomy and infrared astronomy.' So where do you want to draw the line between radio astronomy and infrared astronomy? There's you're answer. |
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What is the highest radio frequency used for radio astronomy?
So where do you want to draw the line between radio astronomy and
infrared astronomy? There's you're answer. Why don't you just call it all electromagnetic astronomy? |
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What is the highest radio frequency used for radio astronomy?
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What is the highest radio frequency used for radio astronomy?
In sci.astro.amateur gwatts wrote:
Radium wrote: Hi: What is the highest radio frequency used for radio astronomy? According to the link below, it is 3438 GHz: http://books.nap.edu/openbook.php?re...=11719&page=11 Is 3438 GHz the highest radio frequency used for radio astronomy? If you read on a little farther you'll find 'blurring the distinction between radio astronomy and infrared astronomy.' So where do you want to draw the line between radio astronomy and infrared astronomy? There's you're answer. Hi, Radium, gwatts, and all. I'd agree that the real question here may be where to draw the line between radio and infrared, and thus between radio astronomy and infrared astronomy. What I learned about 40 years ago was that while the line wasn't a clear one, the shortest or highest-frequency range of radio waves traditionally placed in that classification were "millimeter waves" with a wavelength of 1-10mm. Given that the speed of light, c, is very close to 3 x 10^10 centimeters per second, so that a 1 cm or 10mm wave would have a frequency of around 30 Gz, this category (also known as Extremely High Frequency or EHF) has a 30-300GHz range. A frequency of 3438 GHz, with a wavelength a bit shorter than 100 microns, would thus be about an order of magnitude higher in frequency than the top of the EHF range. While I'm not sure if there's a specific technical name for this range (analogous to the various categories of radio waves like EHF), my first layperson's guess would be that it could be considered very far infrared (that is, far from the visual spectrum and close to radio). It's interesting question how radio and infrared astronomy are distinguished: mainly by the nature of the waves, or also by the apparatus used. I'd like to to learn more of this myself. Again, I'd emphasize that in giving the range for EHF, I'm not saying that anything above 300 GHz wouldn't be considered radio, only mentioning this category as an example of what was traditionally considered near the top of the radio spectrum. Maybe Laura or others could comment more expertly on this. Most appreciatively, Margo Schulter Lat. 38.566 Long. -121.430 |
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What is the highest radio frequency used for radio astronomy?
"Margo Schulter" wrote in message ... In sci.astro.amateur gwatts wrote: Radium wrote: Hi: What is the highest radio frequency used for radio astronomy? According to the link below, it is 3438 GHz: http://books.nap.edu/openbook.php?re...=11719&page=11 Is 3438 GHz the highest radio frequency used for radio astronomy? If you read on a little farther you'll find 'blurring the distinction between radio astronomy and infrared astronomy.' So where do you want to draw the line between radio astronomy and infrared astronomy? There's you're answer. Hi, Radium, gwatts, and all. I'd agree that the real question here may be where to draw the line between radio and infrared, and thus between radio astronomy and infrared astronomy. What I learned about 40 years ago was that while the line wasn't a clear one, the shortest or highest-frequency range of radio waves traditionally placed in that classification were "millimeter waves" with a wavelength of 1-10mm. Given that the speed of light, c, is very close to 3 x 10^10 centimeters per second, so that a 1 cm or 10mm wave would have a frequency of around 30 Gz, this category (also known as Extremely High Frequency or EHF) has a 30-300GHz range. A frequency of 3438 GHz, with a wavelength a bit shorter than 100 microns, would thus be about an order of magnitude higher in frequency than the top of the EHF range. While I'm not sure if there's a specific technical name for this range (analogous to the various categories of radio waves like EHF), my first layperson's guess would be that it could be considered very far infrared (that is, far from the visual spectrum and close to radio). It's interesting question how radio and infrared astronomy are distinguished: mainly by the nature of the waves, or also by the apparatus used. I'd like to to learn more of this myself. Again, I'd emphasize that in giving the range for EHF, I'm not saying that anything above 300 GHz wouldn't be considered radio, only mentioning this category as an example of what was traditionally considered near the top of the radio spectrum. Maybe Laura or others could comment more expertly on this. Most appreciatively, Margo Schulter Lat. 38.566 Long. -121.430 So its your contention that the atmosphere is transparent all the way up from microwaves to IR? |
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What is the highest radio frequency used for radio astronomy?
On Aug 30, 10:34 am, "Peter Webb"
wrote: "Margo Schulter" wrote in message ... In sci.astro.amateur gwatts wrote: Radium wrote: Hi: What is the highest radio frequency used for radio astronomy? According to the link below, it is 3438 GHz: http://books.nap.edu/openbook.php?re...=11719&page=11 Is 3438 GHz the highest radio frequency used for radio astronomy? If you read on a little farther you'll find 'blurring the distinction between radio astronomy and infrared astronomy.' So where do you want to draw the line between radio astronomy and infrared astronomy? There's you're answer. Hi, Radium, gwatts, and all. I'd agree that the real question here may be where to draw the line between radio and infrared, and thus between radio astronomy and infrared astronomy. What I learned about 40 years ago was that while the line wasn't a clear one, the shortest or highest-frequency range of radio waves traditionally placed in that classification were "millimeter waves" with a wavelength of 1-10mm. Given that the speed of light, c, is very close to 3 x 10^10 centimeters per second, so that a 1 cm or 10mm wave would have a frequency of around 30 Gz, this category (also known as Extremely High Frequency or EHF) has a 30-300GHz range. A frequency of 3438 GHz, with a wavelength a bit shorter than 100 microns, would thus be about an order of magnitude higher in frequency than the top of the EHF range. While I'm not sure if there's a specific technical name for this range (analogous to the various categories of radio waves like EHF), my first layperson's guess would be that it could be considered very far infrared (that is, far from the visual spectrum and close to radio). It's interesting question how radio and infrared astronomy are distinguished: mainly by the nature of the waves, or also by the apparatus used. I'd like to to learn more of this myself. Again, I'd emphasize that in giving the range for EHF, I'm not saying that anything above 300 GHz wouldn't be considered radio, only mentioning this category as an example of what was traditionally considered near the top of the radio spectrum. Maybe Laura or others could comment more expertly on this. Most appreciatively, Margo Schulter Lat. 38.566 Long. -121.430 So its your contention that the atmosphere is transparent all the way up from microwaves to IR? Nobody limited the discussion to *terrestrial* astronomy. If one is working from space, the transparency of the atmosphere is irrelevant. Austin |
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What is the highest radio frequency used for radio astronomy?
Peter Webb wrote:
.... So its your contention that the atmosphere is transparent all the way up from microwaves to IR? I didn't see anything referring to atmospheric transparency in Ms. Schulter's response but I'll point you to http://www.alma.nrao.edu/memos/html-...7/memo187.html or 'MMA Memo 187: Modeling of the Submillimeter Opacity on Chajnantor' specifically figures 1-6 which show opacities through air paths and modeled opacities over Mauna Kea, HI. Farther on the authors discuss predicting opacities over the ALMA site in Chile. What it comes down to is: No, the atmosphere is not 'transparent all the way up from microwaves to IR,' but there are windows of transparency where valuable observations can be made. Something else possibly worth perusing is http://www.cv.nrao.edu/naasc/present...07_Handout.pdf and of course the entire ALMA/MMA Memo Series, http://www.alma.info/ |
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What is the highest radio frequency used for radio astronomy?
In sci.astro.amateur gwatts wrote:
Peter Webb wrote: ... So its your contention that the atmosphere is transparent all the way up from microwaves to IR? I didn't see anything referring to atmospheric transparency in Ms. Schulter's response but I'll point you to http://www.alma.nrao.edu/memos/html-...7/memo187.html or 'MMA Memo 187: Modeling of the Submillimeter Opacity on Chajnantor' specifically figures 1-6 which show opacities through air paths and modeled opacities over Mauna Kea, HI. Farther on the authors discuss predicting opacities over the ALMA site in Chile. Hi, Peter, and thank you for your correct conclusion that in my post I really wasn't concerned with transparency or propagation questions, only with the general question of how to describe what I now have learned is often called the submillieter portion of the spectrum. What it comes down to is: No, the atmosphere is not 'transparent all the way up from microwaves to IR,' but there are windows of transparency where valuable observations can be made. That sounds to me like good summary, which would also fit what I recall from the 1960's about certain regions of EHF -- maybe around 60GHz or so -- where attentuation or extinction from water vapor is especially notable. Maybe this is a bit analogous to the absorption lines of visual spectroscopy. Of course, as Laura has pointed out, in space this kind of attenuation is not really a problem! Something else possibly worth perusing is http://www.cv.nrao.edu/naasc/present...07_Handout.pdf and of course the entire ALMA/MMA Memo Series, http://www.alma.info/ Thanks for these links, which I'll study. Most appreciatively, Margo Schulter Lat. 38.566 Long. -121.430 |
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What is the highest radio frequency used for radio astronomy?
"Peter Webb" wrote in message ... "Margo Schulter" wrote in message ... In sci.astro.amateur gwatts wrote: Radium wrote: Hi: What is the highest radio frequency used for radio astronomy? According to the link below, it is 3438 GHz: http://books.nap.edu/openbook.php?re...=11719&page=11 Is 3438 GHz the highest radio frequency used for radio astronomy? .... in frequency than the top of the EHF range. While I'm not sure if there's a specific technical name for this range (analogous to the various categories of radio waves like EHF), my first layperson's guess would be that it could be considered very far infrared (that is, far from the visual spectrum and close to radio). http://en.wikipedia.org/wiki/Electromagnetic_spectrum 3.4THz would be well into the far infra-red. It's interesting question how radio and infrared astronomy are distinguished: mainly by the nature of the waves, or also by the apparatus used. I'd like to to learn more of this myself. Again, I'd emphasize that in giving the range for EHF, I'm not saying that anything above 300 GHz wouldn't be considered radio, only mentioning this category as an example of what was traditionally considered near the top of the radio spectrum. .... So its your contention that the atmosphere is transparent all the way up from microwaves to IR? I don't believe Margo suggested that at all. This page lists some of the sources of line features in that region: http://kp12m.as.arizona.edu/docs/wha...millimeter.htm George |
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