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 3332.0 - 3339.0 MHz
• 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):

3300 - 3400 MHz: 	RADIOLOCATION
			
			5.149 5.429 5.430
					

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

• Armenia: no allocation or reference to No. 5.149
• Bulgaria: no allocation or reference to No. 5.149
• Estonia: no allocation or reference to No. 5.149
• Finland: no allocation or reference to No. 5.149
• Italy: "footnote" secondary allocation
• Liechtenstein: no allocation or reference to No. 5.149
• Luxembourg: no allocation or reference to No. 5.149
• the Netherlands: notification of use
• Russian Federation: no allocation or reference to No. 5.149
• Sweden: notification of use
• Turkey: no allocation or reference to No. 5.149
• United Kingdom: no allocation or reference to No. 5.149

Astrophysical importance of the band 3332.0 - 3339.0 MHz

Three molecular lines of the CH molecule have been detected at 3263, 3335 and 3349 MHz. These frequencies are unfortunately only allocated to radio astronomy by No. 5.149, however the study of interstellar CH is considered to be extremely important in understanding the chemistry of the interstellar material. The presence of CH suggests the existence of the molecule CH4 (methane) which is considered one of the basic molecules for the initial stages of the formation of life.

(see IAU list of important spectral lines)

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	2.83 mK	-254 dB(WHz-1)	-219 dBW	-183 dB(Wm-2)	-230 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 3332.0 - 3339.0 MHz is used by the Radio Astronomy Service in:

• Czechia
• France
• Germany
• Italy
• Sweden
• Turkey

Threats to the Radio Astronomy Service:

Sharing problems with the following service:

• Radiolocation Service