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 151.5 - 155.5 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):

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


151.5 - 155.5 GHz:	FIXED
			MOBILE
			RADIO ASTRONOMY
			RADIOLOCATION
			
			5.149


155.5 - 158.5 GHz:	EARTH EXPLORATION-SATELLITE (passive) 5.562F
			FIXED
			MOBILE
			RADIO ASTRONOMY
			SPACE RESEARCH (passive) 5.562B
			
			5.149 5.562G

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 151.5 - 155.5 GHz

This frequency band is used for both spectral line and continuum observations. Among the important spectral lines in this band the lines of Methyl acetylene (CH₃CCH) and Cyanoacetylene (HC₃N) with rest frequencies of 153.8 GHz and 154.657 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	-138 dB(Wm-2)	-199 (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	0.043 mK	-272 dB(WHz-1)	-186 dBW	-120 dB(Wm-2)	-217 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 151.5 - 155.5 GHz is used by the Radio Astronomy Service in:

• Russia
• 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:

• Fixed Service
• Mobile Service