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 76 - 77.5 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):

75.5 - 76 GHz:		FIXED
			FIXED-SATELLITE (space-to-Earth)
			MOBILE
			BROADCASTING
			BROADCASTING-SATELLITE
			Space research (space-to-Earth)

			5.561  5.559A

76 - 77.5 GHz:		RADIO ASTRONOMY
			RADIOLOCATION
			Amateur
			Amateur-satellite
			Space research (space-to-Earth)
		
			5.149

77.5 - 78 GHz:		AMATEUR
			AMATEUR-SATELLITE
			Radio astronomy
			Space research (space-to-Earth)
			
			5.149

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

• Armenia: no allocation
• Liechtenstein: no allocation
• Russian Federation: no allocation
• Turkey: no allocation

Astrophysical importance of the band 76 - 77.5 GHz

This frequency band is used for both spectral line and continuum observations.

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	2.87 mK	-254 dB(WHz-1)	-204 dBW	-144 dB(Wm-2)	-204 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	0.044 mK	-272 dB(WHz-1)	-187 dBW	-129 dB(Wm-2)	-224 dB(Wm-2Hz-1)
Interferometer					-198 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 76 - 77.5 GHz is used by the Radio Astronomy Service in:

• Germany
• France
• Italy
• Spain
• Sweden

Threats to the Radio Astronomy Service:

Sharing problems with the following service:

• Radiolocation Service (specific cases)

  Out-of-band emission from the following services:

• Amateur Service
• Amateur-Satellite Service
• Broadcasting Service
• Broadcasting-Satellite Service
• Fixed Service
• Fixed-Satellite Service
• Mobile Service