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):


209 - 217   GHz:	FIXED
			FIXED-SATELLITE (Earth-to-space)
			MOBILE
			RADIO ASTRONOMY
			
			5.149 5.341


217 - 226   GHz:	FIXED
			FIXED-SATELLITE (Earth-to-space)
			MOBILE
			RADIO ASTRONOMY
			SPACE RESEARCH (passive) 5.562B
		
			5.149 5.341


226 - 231.5 GHz:	EARTH EXPLORATION-SATELLITE (passive)
			RADIO ASTRONOMY
			SPACE RESEARCH (passive)
			
			5.340

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

Astrophysical importance of the band 217 - 226 GHz

This frequency band is used for both spectral line and continuum observations. Among the important spectral lines in this band the lines of Silicon monoxide (SiO), Deuterium cyanide (DCN), Formaldehyde (H2CO), Carbon monoxide (C18O), Carbon monoxide (13CO), Methyl cyanide (CH3CN), Sulphur dioxide (SO2), Methyl acetylene (CH3CCH), Carbon monoxide (C17O), Sulphur dioxide (SO2) and Deuterated water (HDO) with rest frequencies of 217.105 GHz, 217.239 GHz, 218.222 GHz, 219.560 GHz, 220.399 GHz, 220.7 GHz, 221.965 GHz, 222.1 GHz, 224.714 GHz, 225.154 GHz and 225.897 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
TemperaturePower Spectral DensityInput PowerPower Flux DensitySpectral Power Flux Density
Single Dish2.40 mK-255 dB(WHz-1)-201 dBW-133 dB(Wm-2)-197 (Wm-2Hz-1)

Threshold levels of interference detrimental to radio astronomy continuum observations:

System Sensitivity (noise fluctuations)Threshold Interference Levels
TemperaturePower Spectral DensityInput PowerPower Flux DensitySpectral Power Flux Density
Single Dish0.033 mK-274 dB(WHz-1)-182 dBW-114 dB(Wm-2)-215 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 217 - 226 GHz is used by the Radio Astronomy Service in:

Threats to the Radio Astronomy Service:

Last modified: January 25, 2005