Committee on Radio Astronomy Frequencies

The Committee on Radio Astronomy Frequencies (CRAF) is a committee of the European Science Foundation (ESF).

Frequency band allocated to the Radio Astronomy Service:

• ITU-RR allocations (+ footnotes)
• National Arrangements for Radio Astronomy different from ITU-R Radio Regulations
• Astrophysical importance of the band 105 - 109.5 GHz
• Threshold levels of interference detrimental to radio astronomy
• Radio Astronomy use of this band in Europe
• Threats to the Radio Astronomy Service

ITU-RR allocations (+ footnotes):

102   - 105   GHz:	FIXED
			MOBILE
			RADIO ASTRONOMY
			
			5.149 5.341


105   - 109.5 GHz:	FIXED
			MOBILE
			RADIO ASTRONOMY
			SPACE RESEARCH (passive) 5.562B

			5.149 5.341


109.5 - 111.8 GHz:	EARTH EXPLORATION-SATELLITE (passive)
			RADIO ASTRONOMY
			SPACE RESEARCH (passive)
			
			5.340 5.341

National Arrangements for Radio Astronomy different from ITU-R Radio Regulations:

• Liechtenstein: no allocation

Astrophysical importance of the band 105 - 109.5 GHz

This frequency band is used for both spectral line and continuum observations. Among the important spectral lines in this band the lines of Cyanoacetylene (HC₃N) and Sulphur monoxide (SO) with rest frequencies of 109.174 GHz and 109.252 GHz, respectively, should be noted.

See also: mm-Wavelength Astronomy.

Threshold levels of interference detrimental to radio astronomy spectral-line observations:

	System Sensitivity (noise fluctuations)		Threshold Interference Levels
	Temperature	Power Spectral Density	Input Power	Power Flux Density	Spectral Power Flux Density
Single Dish	3.08 mK	-254 dB(WHz-1)	-204 dBW	-142 dB(Wm-2)	-202 dB(Wm-2Hz-1)

Threshold levels of interference detrimental to radio astronomy continuum observations:

	System Sensitivity (noise fluctuations)		Threshold Interference Levels
	Temperature	Power Spectral Density	Input Power	Power Flux Density	Spectral Power Flux Density
Single Dish	0.031 mK	-274 dB(WHz-1)	-184 dBW	-122 dB(Wm-2)	-222 dB(Wm-2Hz-1)

NOTE:

For further details the reader is referred to ITU-R Recommendation RA769. It should, however, be noted that the observed spectral power flux densities are much lower than the harmful interference levels because they are made in the main beam of the radio astronomy antennas whereas the harmful levels correspond to reception in the sidelobes, i.e. the differences are related to the gain of the antennas. The differences can be of the order of 50 to 80 dB W m^-2 Hz^-1 (see ITU-R "Handbook on Radio Astronomy", 1995/2003, chapter 4).

In Europe, the band 105 - 109.5 GHz is used by the Radio Astronomy Service in:

• Finland
• France
• Spain
• Sweden

Threats to the Radio Astronomy Service:

Sharing problems with the following services:

• Fixed Service
• Mobile Service

  Out-of-band emission from the following services:

• Fixed Service
• Mobile Service