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What is the highest radio frequency used for radio astronomy?
On 30 Aug 2007 15:03:23 GMT, Margo Schulter
wrote: 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). They are called submillimeter waves, and represent the transition between what is widely accepted as "radio" and what is widely accepted as "optical". IMO the best way to categorize EM bands is by the nature of the equipment we use to measure energy in those bands. Submillimeter radiation is detected using special receivers which combine optical-like sensors (bolometers) and radio-like sensors (heterodyne receivers and tuned antennas). I think its best to simply consider the range from about one millimeter to 1/10 millimeter as "submillimeter", neither radio nor optical (IR). _________________________________________________ Chris L Peterson Cloudbait Observatory http://www.cloudbait.com |
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What is the highest radio frequency used for radio astronomy?
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? She didnt say anything at all about this. Why are you "contending" contenacity contumaciously? |
#13
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What is the highest radio frequency used for radio astronomy?
In article om,
laura halliday wrote: The usual agreement is that it's radio astronomy when the incoming signals are electronically detected (e.g. diodes) and processed. It's optical/infrared astronomy when the incoming signals are measured by a bolometer or other non-electronic means. There is, naturally, some crossover. Given today's CCD chips which indeed are electronic devices, does that mean todays optical telescopes, with CCD chips which detect light electronically, have become radio telescopes? -- ---------------------------------------------------------------- Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN e-mail: pausch at stockholm dot bostream dot se WWW: http://stjarnhimlen.se/ |
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What is the highest radio frequency used for radio astronomy?
In article ,
Chris L Peterson wrote: IMO the best way to categorize EM bands is by the nature of the equipment we use to measure energy in those bands. Submillimeter radiation is detected using special receivers which combine optical-like sensors (bolometers) and radio-like sensors (heterodyne receivers and tuned antennas). I think its best to simply consider the range from about one millimeter to 1/10 millimeter as "submillimeter", neither radio nor optical (IR). Or perhaps we could consider that wavelength band both "optical" and "radio", since radiation at those wavelengths probably can be detected both with radio and with optical equipment. And if one wants to decide on some single wavelength limit between "radio" and "optical", 0.3 millimeter appears to be a good choice since it resides near the middle of this "submillimeter" band. This corresponds to a frequency of one TeraHertz. -- ---------------------------------------------------------------- Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN e-mail: pausch at stockholm dot bostream dot se WWW: http://stjarnhimlen.se/ |
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What is the highest radio frequency used for radio astronomy?
Paul Schlyter wrote:
And if one wants to decide on some single wavelength limit between "radio" and "optical", 0.3 millimeter appears to be a good choice since it resides near the middle of this "submillimeter" band. This corresponds to a frequency of one TeraHertz. And in fact, e-m radiation at and around that frequency is often called Terahertz radiation, or Terahertz waves, or T-rays, etc. More specifically, from 300 GHz to 3 THz is the Terahertz band. This terminology seems to be used more in non-astronomical fields. http://en.wikipedia.org/wiki/Terahertz -- Dan Tilque |
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What is the highest radio frequency used for radio astronomy?
In article ,
Paul Schlyter wrote: That's a little illogical. It's like considering a frequency slightly above 300 kHz to belong to "the Megahertz band" .... Seems logical to me. Anything above 316kHz is nearer to 1MHz than to 100kHz. -- Richard -- "Consideration shall be given to the need for as many as 32 characters in some alphabets" - X3.4, 1963. |
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What is the highest radio frequency used for radio astronomy?
In article ,
Dan Tilque wrote: Paul Schlyter wrote: And if one wants to decide on some single wavelength limit between "radio" and "optical", 0.3 millimeter appears to be a good choice since it resides near the middle of this "submillimeter" band. This corresponds to a frequency of one TeraHertz. And in fact, e-m radiation at and around that frequency is often called Terahertz radiation, or Terahertz waves, or T-rays, etc. More specifically, from 300 GHz to 3 THz is the Terahertz band. This terminology seems to be used more in non-astronomical fields. http://en.wikipedia.org/wiki/Terahertz That's a little illogical. It's like considering a frequency slightly above 300 kHz to belong to "the Megahertz band" .... -- Dan Tilque -- ---------------------------------------------------------------- Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN e-mail: pausch at stockholm dot bostream dot se WWW: http://stjarnhimlen.se/ |
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What is the highest radio frequency used for radio astronomy?
In article ,
Richard Tobin wrote: In article , Paul Schlyter wrote: That's a little illogical. It's like considering a frequency slightly above 300 kHz to belong to "the Megahertz band" .... Seems logical to me. Anything above 316kHz is nearer to 1MHz than to 100kHz. There's a difference between "the Megahertz band" and "the One Megahertz band". The former can be interpreted as the band from 1 MHz to 1 GHz for instance, instead of your interpretation from 0.316 to 3.16 MHz.... -- Richard -- "Consideration shall be given to the need for as many as 32 characters in some alphabets" - X3.4, 1963. -- ---------------------------------------------------------------- Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN e-mail: pausch at stockholm dot bostream dot se WWW: http://stjarnhimlen.se/ |
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What is the highest radio frequency used for radio astronomy?
On Fri, 31 Aug 2007 12:13:05 GMT, (Paul Schlyter) wrote:
That's a little illogical. It's like considering a frequency slightly above 300 kHz to belong to "the Megahertz band" .... No, it's _more_ logical. It's having arbitrary names for various regions of the EM spectrum that isn't entirely logical. _________________________________________________ Chris L Peterson Cloudbait Observatory http://www.cloudbait.com |
#20
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What is the highest radio frequency used for radio astronomy?
On Aug 30, 12:33 am, 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? Thanks, Radium For obtaining eye candy that's entirely outside of our physical reach, and for the most part having been getting further away as we speak, the 3.438 THz might be fine and dandy for accomplishing that spendy look-see which can't possibly benefit humanity or that of our badly failing environment. Much above 0.1 THz is where such photons if transmitted from Earth simply do not reflect unless the target offers a nifty array of parabolic dishes, or of some other artificial reflective surface. Outside of our magnetosphere, such as within our moon's L1, is where X band of 8 ~ 12.5 GHz or possibly as great as Ka Band of 26.5 ~ 40 GHz might become interesting and/or essential if future space travel is to avoid those nasty bits and pieces of debris that'll otherwise clean your clock upon encountering such, with C Band of 4 ~ 8 GHz being a little better off for those slightly larger targets and perhaps best of all S Band of 2 ~ 4 GHz offering a compromise that'll still yield more than sufficient image resolution of a given planet or moon, along with offering a darn good reflective signal to noise ratio. However, if the potential target is the least bit intelligent worthy, as many should be, as such why not use a blue~violet laser cannon, UV- a, or possibly good old X-rays or even gamma ? Though gravity can be directly measured, of what we can't manage thus far is the two-way frequency applications of utilizing said gravitons. Perhaps there again, the mutual gravity nullification zone of our moon's L1 could allow for the limited use of gravitons, and this alternative might become better yet once we've relocated that moon to Earth's L1. - Brad Guth |
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