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 250 - 252 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):


248 - 250 GHz: 		AMATEUR
			AMATEUR-SATELLITE
			Radio astronomy
			
			5.149


250 - 252 GHz:		EARTH EXPLORATION-SATELLITE (passive)
			RADIO ASTRONOMY
			SPACE RESEARCH (passive)
			
			5.340 5.563A


252 - 265 GHz:		FIXED
			MOBILE
			MOBILE-SATELLITE (Earth-to-space)
			RADIO ASTRONOMY
			RADIONAVIGATION
			RADIONAVIGATION-SATELLITE
			
			5.149 5.554

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

Armenia: no allocation
Liechtenstein: no allocation but No. 5.340 applies
Russian Federation: no allocation

Astrophysical importance of the band 250 - 252 GHz

This frequency band is used for both spectral line and continuum observations. Among the important spectral lines in this band the lines of Nitric oxide (NO) and Sulphur dioxide (SO₂) with rest frequencies of 250.6 GHz and 251.211 GHz, respectively, should be noted.

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 2.40 mK -255 dB(WHz^-1) -201 dBW -132 dB(Wm^-2) -196 (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 0.036 mK -273 dB(WHz^-1) -183 dBW -113 dB(Wm^-2) -214 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 250 - 252 GHz is used by the Radio Astronomy Service in:

Spain

Threats to the Radio Astronomy Service:

Out-of-band emission from the following services:

Last modified: March 16, 2005

	System Sensitivity (noise fluctuations)		Threshold Interference Levels
	Temperature	Power Spectral Density	Input Power	Power Flux Density	Spectral Power Flux Density
Single Dish	2.40 mK	-255 dB(WHz^-1)	-201 dBW	-132 dB(Wm^-2)	-196 (Wm^-2Hz^-1)