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):


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


265 - 275 GHz:		FIXED
			FIXED-SATELLITE (Earth-to-space)
			MOBILE
			RADIO ASTRONOMY
			
			5.149 5.563A

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

Astrophysical importance of the band 252 - 265 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 cyanide (CH3CN), Hydrogen cyanide (H13CN), Formylium (H13CO+), Silicon monoxide (SiO), Hydrogen isocyanide (HN13C), Ethynyl radical (C2H) and Sulphur dioxide (SO2) with rest frequencies of 257.5 GHz, 259.012 GHz, 260.255 GHz, 260.518 GHz, 261.263 GHz, 262.000 GHz and 262.334 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-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
TemperaturePower Spectral DensityInput PowerPower Flux DensitySpectral Power Flux Density
Single Dish0.036 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 252 - 265 GHz is used by the Radio Astronomy Service in:

Threats to the Radio Astronomy Service:

Last modified: January 25, 2005