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):


315 - 322  MHz:		FIXED
			MOBILE
			
			5.254
			

322  - 328.6 MHz: 	FIXED
			MOBILE
			RADIO ASTRONOMY
			
			5.149
			

328.6 - 335.4  MHz:	AERONAUTICAL RADIONAVIGATION
		
			5.258 5.259

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

Astrophysical importance of the band 322.0 - 328.6 MHz

The band 322 - 328.6 MHz is increasingly being used in all regions, because major telescopes are operating or planned on these frequencies to study the structure of radio galaxies. There will be strong pressure, internationally, for increased protection of this band, including especially the avoidance of transmissions from satellites and aircraft.

This band has the desired octave-spacing relation with the 150.05 - 153 MHz and 608 - 614 MHz bands, which is needed for continuum observations and in addition it contains an important atomic spectral line: the hyperfine- structure spectral line of deuterium at 327.4 MHz. The relative abundance of deuterium to hydrogen is related to the problems of the origin of the universe and the synthesis of the elements. A determination of the deuterium abundance in the universe will certainly help in defining the most probable theory of the origin and evolution of the universe. Recent ultra-violet observations of deuterium show that its abundance is not uniform, suggesting that studies of its abundance may be of increasing importance.

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 Dish0.87 mK-259 dB(WHz-1)-201 dBW-189 dB(Wm-2)-258 dB(Wm-2Hz-1)
Interferometer-253 dB(Wm-2Hz-1)
VLBI-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 322 - 328.6 MHz is used by the Radio Astronomy Service in:

Threats to the Radio Astronomy Service:

Last modified: March 21, 2005