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 126 - 130 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):

123 - 126 GHz:		FIXED-SATELLITE (space-to-Earth)
			MOBILE-SATELLITE (space-to-Earth)
			RADIONAVIGATION
			RADIONAVIGATION-SATELLITE
			Radio astronomy
		
			5.554


126 - 130 GHz:		FIXED-SATELLITE (space-to-Earth)
			MOBILE-SATELLITE (space-to-Earth)
			RADIONAVIGATION
			RADIONAVIGATION-SATELLITE
			Radio astronomy 5.562D

			5.149 5.554


130 - 134 GHz:		EARTH EXPLORATION-SATELLITE (active) 5.562E
			FIXED
			INTER-SATELLITE
			MOBILE  5.558
			RADIO ASTRONOMY
		
			5.149 5.562A

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

• Armenia: no allocation or reference to No. 5.149
• Liechtenstein: no allocation or reference to No. 5.149
• Russian Federation: no allocation or reference to No. 5.149

Astrophysical importance of the band 126 - 130 GHz

This frequency band is used for both spectral line and continuum observations. Among the important spectral lines in this band the line of Silicon monoxide (SiO) with rest frequency of 127.269 GHz 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	2.79 mK	-254 dB(WHz-1)	-203 dBW	-140 dB(Wm-2)	-200 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	0.034 mK	-273 dB(WHz-1)	-184 dBW	-121 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 126 - 130 GHz is used by the Radio Astronomy Service in:

• Spain

Threats to the Radio Astronomy Service:

Sharing problems with the following services:

• Fixed-Satellite Service
• Mobile-Satellite Service
• Radionavigation Service
• Radionavigation-Satellite Service

  Out-of-band emission from the following services:

• Earth Exploration-Satellite Service
• Fixed Service
• Fixed-Satellite Service
• Inter-Satellite Service
• Mobile Service
• Mobile-Satellite Service
• Radionavigation Service
• Radionavigation-Satellite Service