ESF logo Committee on Radio Astronomy Frequencies

 The Committee on Radio Astronomy Frequencies (CRAF) is an Expert Committee of the European Science Foundation (ESF).

Frequency band allocated to the Radio Astronomy Service:

ITU-RR allocations (+ footnotes):


5925  -  6700  MHz:	FIXED
			FIXED-SATELLITE (Earth-to-space) 5.457A 5.457B
			MOBILE 5.547C
			
			5.149 5.440 5.458
			

6 700  -  7 075 MHZ:    FIXED
                        FIXED-SATELLITE (Earth-to-space) (space-to-Earth) 5.441
                        MOBILE
                        5.458 5.458A 5.458B 5.458C

Astrophysical importance of the band 6650 - 6675.2 MHz

This is vey important band for observations of Methanol (CH2OH) spectral lines.
The line was only discovered in 1991 and has become an important diagnostic for the conditions in high-mass star formation regions. Also, the study of such regions is important for the understanding of the formation of our solar system and the composition of elements in Sun and planets. That is one of the reasons for which extensive new research and equipment programmes have been started in several European countries. Significant investments in new dedicated receivers for this frequency band are made all over the world.
Regrettably, the present regulatory status does not reflect the importance of this band for the modern radio 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 Dish2.20 mK-255 dB(WHz-1)-218 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 6650 - 6675.2 MHz is used by the Radio Astronomy Service in:

This is a very important band for European VLBI Network (EVN) and Multi-Element Radio Linked Interferometer Network (MERLIN).

Threats to the Radio Astronomy Service:

Last modified: October 6, 2009