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):


25.21 - 25.55 MHz:	FIXED
			MOBILE except aeronautical mobile
			

25.55 - 25.67 MHz: 	RADIO ASTRONOMY
			
			5.149
		
			
25.67 - 26.10 MHz:	BROADCASTING

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

Astrophysical importance of the band 25.55 - 25.67 MHz

The band 25.55 - 25.67 MHz has worldwide a shared primary allocation (see also No. 5.149). This bands is very important for observations of decametric radiation from the planet Jupiter and from the Sun.

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 Dish972 mK-229 dB(WHz-1)-188 dBW-199 dB(Wm-2)-249 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 25.55 - 25.67 MHz is used by the Radio Astronomy Service in:

Threats to the Radio Astronomy Service:

Last modified: March 16, 2005