RADIO ASTRONOMY FREQUENCY ALLOCATIONSThis section shows frequencies allocated for radio astronomy in the European Union. This is byinternational agreement. Certain scientifically important frequency bands are kept clear of radiotransmissions, allowing radio astronomers to detect the faint signals from cosmic sources.

In practice, there is still some interference. Some of these frequency bands are close in frequency to legal,high power transmitters. High signal levels out of the radio astronomy bands can still desensitize radiotelescope receivers. All practical transmitters also radiate a small fraction of power away from theirallocated frequencies, called 'spurious' signals. These spurious signals are very small, but still many timeslarger than the signals radio astronomers are trying to detect. For these reasons the most sensitive radiotelescopes are as far away from civilization as possible and normally make use of very good filters.

Radio Astronomy frequency allocations don't mean that you can ONLY use these frequencies for radioastronomy. Any frequency for which the atmosphere is transparent can be used. The problem is that otherfrequencies are assigned to other services which might cause interference to your radio telescope. The 88 -108 MHz FM broadcast band is a good example of this.

Jupiter's most interesting radiation is between about 15Mhz and 30MHz. In this range there is only onevery small, officially allocated band. To study Jupiter's radiation in this band, the radio astronomer has tocontend with transmissions from all over the world as well as computer- and television interference. Theradio astronomer is forced to work outside the allocated frequency range and has to learn to distinguishbetween all kinds of noise and that coming from Jupiter.

In most cases, interesting frequencies have been set aside for radio astronomy. This is thanks to the hardwork of radio astronomers through the years to keep these frequencies clear of terrestrial and satellitetransmissions. In future their work will become harder as commercial demands on frequency usage makeit very difficult for regulators to justify allocating frequencies for scientific purposes.

Table of frequency allocations for European radio astronomers:

Frequency band Designation Radio astronomy use Comments13.36 - 13.41 MHz HF25.55 - 25.67 MHz HF37.5 - 38.25 MHz VHF Continuum observations

73 - 74.6 MHz VHF Solar wind observations.1. Continuum observations.2.

150.05 - 153 MHz VHF Continuum observations.1. Pulsar observations.2. Solar observations.3.

322 - 328.6 MHz UHF Continuum observations.1. VLBI2.

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406.1 - 410 MHz UHF Continuum observations.1. Pulsar observations.2.

608 - 614 MHz UHF Continuum observations.1. VLBI2.

1400 - 1427 MHz ** L-band Spectral line observations 21cm hydrogen line1660 - 1660.5 MHz L-band VLBI

1660.5 - 1668.4 MHz L-band VLBI1. Line observations.2. Continuum observations.3.

1668.4 - 1670 MHz L-band1718.8 - 1722.2 MHz L-band

2655 - 2690 MHz S-band Continuum observations2690 - 2700 MHz S-band3260 - 3267 MHz S-band3332 - 3339 MHz S-band

3345.8 - 3352.5 MHz S-band4800 - 4990 MHz C-band Continuum observations4990 - 5000 MHz C-band Continuum observations.1.

VLBI2.

5000 - 5030 MHz C-band VLBI6650 - 6675.2 MHz C-band10.6 - 10.68 GHz X-band Continuum meausurements.1.

VLBI2.

10.68 - 10.7 GHz X-band Continuum observations.1. VLBI2.

14.47 - 14.5 GHz Ku-band Spectral line observations.1. VLBI2.

15.2 - 15.35 GHz Ku-band VLBI15.35 - 15.4 GHz Ku-band Continuum observations.1.

VLBI2.

22.01 - 22.21 GHz Ka-band Spectral line observations Water line.22.21 - 22.5 GHz Ka-band Spectral line observations Water line.

22.91 - 22.86 GHz Ka-band Spectral line observations Methyl Formate1. Ammonia2.

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23.07 - 23.12 GHz Ka-band Spectral line observations23.6 - 24.0 GHz Ka-band Spectral line observations1.

Continuum observations2. Ammonia line

31.2 - 31.3 GHz Ka-band Continuum observations31.3 - 31.5 GHz Ka-band Continuum observations31.5 - 31.8 GHz Ka-band Continuum observations

36.43 - 36.5 GHz Ka-band Spectral line observations Hydrogencyanide

1.

Hydroxil2.

42.5 - 43.5 GHz Q-band Spectral line observations Silicon monoxide andmany other lines.

48.94 - 49.04 GHz Q-band Spectral line observations Carbon monosulphide51.4 - 54.25 GHz V-band

58.2 - 59 GHz V-band72.77 - 72.91 GHz V-band Spectral line observations Formaldehyde line.

86 - 92 GHz W-band Spectral line observations.1. Continuum obserations.2.

92 - 94 GHz Spectral line observations. Diazenylium and manyother lines.

95 - 100 GHz Spectral line observations.1. Continuum observations.2.

** Note that frequencies above 1GHz (1000MHz) are collectively referred to as microwave frequencies.Microwave frequencies are further classified as L-band, S-band, C-band, etc.

References

Frequency range 29.7 MHz to 105 GHz and associated European table of frequencyallocations and utilisations. June 1994. Revised March 1995 and February 1998.

1.

Table of frequencies allocated to radio astronomy, the Earth exploration satellite, and spaceresearch. http://www.aoc.nrao.edu/vla/html/rfa.htm

2.

Basics of Space Flight - Chapter 6: Electromagnetic phenomena. http://www.jpl.nasa.gov/basics/bsf6-3.html

3.

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