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 141 - 148.5 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):

136   - 141   GHz:	RADIO ASTRONOMY
			RADIOLOCATION
			Amateur
			Amateur-satellite
			
			5.149


141   - 148.5 GHz:	FIXED
			MOBILE
			RADIO ASTRONOMY
			RADIOLOCATION
			
			5.149


148.5 - 151.5 GHz:	EARTH EXPLORATION-SATELLITE (passive)
			RADIO ASTRONOMY
			SPACE RESEARCH (passive)
			
			5.340

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

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

Astrophysical importance of the band 141 - 148.5 GHz

This frequency band is used for both spectral line and continuum observations. Among the important spectral lines in this band the lines of Deuterated formylium (DCO⁺), Deuterium cyanide (DCN), Formaldehyde (H₂CO), Carbon monosulphide (CS) and Methyl cyanide (CH₃CN) with rest frequencies of 144.077 GHz, 144.828 GHz, 145.603 GHz, 146.969 GHz and 147.17 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	2.45 mK	-255 dB(WHz-1)	-203 dBW	-139 dB(Wm-2)	-200 (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	0.038 mK	-273 dB(WHz-1)	-185 dBW	-121 dB(Wm-2)	-218 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 141 - 148.5 GHz is used by the Radio Astronomy Service in:

• France
• Spain

Threats to the Radio Astronomy Service:

Sharing problems with the following services:

• Fixed Service
• Mobile Service
• Radiolocation Service

  Out-of-band emission from the following services:

• Radiolocation Service