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 241 - 248 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):

240 - 241 GHz:		FIXED
			MOBILE
			RADIOLOCATION


241 - 248 GHz:		RADIO ASTRONOMY
			RADIOLOCATION
			Amateur
			Amateur-satellite
			
			5.138 5.149


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

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 241 - 248 GHz

This frequency band is used for both spectral line and continuum observations. Among the important spectral lines in this band the lines of Carbon monosulphide (C³⁴S), Deuterated water (HDO), Methanol (CH₃OH) (4 lines) and Carbon monosulphide (CS) with rest frequencies of 241.016 GHz, 241.562 GHz, 241.700 GHz, 241.767 GHz, 241.791 GHz, 241.842 GHz and 244.953 GHz 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	2.40 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
	Temperature	Power Spectral Density	Input Power	Power Flux Density	Spectral Power Flux Density
Single Dish	0.034 mK	-274 dB(WHz-1)	-182 dBW	-114 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 241 - 248 GHz is used by the Radio Astronomy Service in:

• Spain

Threats to the Radio Astronomy Service:

Sharing problems with the following services:

• Radiolocation Service

  Out-of-band emission from the following services:

• Amateur Service
• Amateur-Satellite Service
• Fixed Service
• Mobile Service
• Radiolocation Service