CRAF Newsletter 1999/2

May 1999

The European Science Foundation is an association of its 62 member research councils and academies in 21 countries. The ESF brings European scientists together to work on topics of common concern, to co-ordinate the use of expensive facilities, and to discover and define new endeavors that will benefit from a co-operative approach
The scientific work sponsored by ESF includes basic research in the natural sciences, the medical and biosciences, the humanities and the social sciences.
The ESF links scholarship and research supported by its members and adds value by cooperation across national frontiers. Through its function as coordinator, and also by holding workshops and conferences and by enabling researchers to visit and study in laboratories throughout Europe, the ESF works for the advancement of European science.

On behalf of European radio astronomers, the ESF Committee on Radio Astronomy Frequencies, CRAF, coordinates activities to keep the frequency bands used by radio astronomers free from interference.


1. Editorial

On May 26, 1999, the European Science Foundation, ESF, signed an agreement with Iridium LLC, providing a further degree of protection of radio astronomy in the important band 1610.6 - 1613.8 MHz from out-of-band emissions of the satellite transmissions of the Iridium system in the band 1621.35 - 1626.5 MHz for the period 1 May 1999 - 1 January 2006. This interim agreement arose from the ESF-Iridium LLC Framework Agreement of 1998 (see also CRAF Newsletter 1998-3).

The interim agreement was reached after 6 months of intensive and harsh negotiations. However, radio astronomers are not overjoyed about the results since they have significant impact on radio astronomy operations in the band 1610.6-1613.8 MHz in Europe and contain potential regulatory complications.

During the negotiations, CRAF made significant concessions and compromises necessary to reach this agreement. This attitude is a strikingly different from Iridium LLC's position which furthermore was not supported by experimental data such as measured data of the unwanted emission spectrum, measured data on antenna patterns, and real data on customer traffic. During the negotiations, the CRAF recommended to Iridium LLC to give priority to the GSM functionality of its mobile phones in Europe: GSM operates at frequencies sufficiently distant from radio astronomy frequencies. Such a priority would not have negative impact on the operational quality of the Iridium system including its satellite component (traffic to/from the satellites is done via the European gateway stations). Therefore, by setting this priority, the issue at stake could be alleviated in a very elegant way. However, Iridium LLC was not able to consider this option.

Nevertheless, CRAF appreciates that the new agreement guarantees that unwanted emissions from the Iridium satellite system from the band 1621.35-1626.5 MHz into the band 1610.6-1613.8 MHz is kept below the levels documented in Recommendation RA.769-1 of the International Telecommunication Union, ITU, for up to about 50% of the time. This should be noted.

T.A.Th.Spoelstra - Dwingeloo

2. Radio Astronomy at 1612 MHz

Radio astronomy has a primary allocation in the frequency band 1610.6-1613.8 MHz which covers an important spectral line of hydroxyl (OH), one of the simplest and most common interstellar molecules.

The 1612 MHz line of OH is used by astronomers to investigate many astronomical processes, including the birth and eath of stars, the evaporation of comets, and active nuclei in distant galaxies. The hydroxyl emissions come from regions which are hidden from optical telescopes by clouds of dust and gas. The OH 1612 MHz line is characteristic of a special class of astronomical sources, the OH-IR sources, which can only be studied through their hydroxyl and infrared emission.

Europe has world-leading facilities for studying hydroxyl sources:
The large radio telescope at Nançay is second in collecting area only to the giant 300-m reflector at Arecibo, Puerto Rico. The Nançay radio telescope spends half of its time observing hydroxyl sources. It has recently been upgraded to greatly improve its sensitivity.

The 100-m telescope at Effelsberg. Germany, is the largest fully steerable radio telescope in the world, and the 76-m telescope at Jodrell Bank in the United Kingdom is the second largest fully steerable telescope in the world operatimng at the frequency of 1612 MHz.

The MERLIN network of radio telescopes in the United Kingdom is the world's leading instrument for imaging 1612 MHz sources. MERLIN images together with single-telescope monitoring observations, such as those carried out at Nançay, enable astronomers to measure accurately the distances of OH 1612 MHz sources, and may soon give our most accurate measurement of the size of the Galaxy in which we live.

The Westerbork Synthesis Radio Telescope in the Netherlands is one of the most sensitive instruments in the world for detecting new 1612 MHz sources and monitoring their emissions.

The European VLBI Network is the most sensitive very-long-baseline interferometer network in the world for imaging the fine structure in OH 1612 MHz sources.

3. ESF-Iridium LLC Framework Agreement

Between November 1998 and May 1999, CRAF and Iridium LLC worked in several meetings towards an agreement for the period 1 May 1999 - 1 January 2006 as anticipated in the ESF-Iridium LLC Framework Agreement which was reached on August 11th, 1998. CRAF represented the interests of the European radio astronomy community. The key issue in the discussions was the protection of radio astronomy in the frequency band 1610.6-1613.8 MHz from unwanted emissions from the Iridium satellite system operating in the band 1621.35-1626.5 MHz and to define circumstances under which both European radio astronomy stations and the Iridium system can operate during the indicated period. The legal basis for these discussions formed the ESF-Iridium LLC Framework Agreement, the ITU-R Radio Regulations, Recommedation ITU-R RA769-1 as well as the European Commission's licensing directive (97/13/EC) and relevant CEPT(ERC/ECTRA) decisions and recommendations.

The CEPT Milestone Review Committee delegated its chairman, secretary and two of its members to observe the proceedings of the negotiations. In several instances they also gave advice to both CRAF and Iridium LLC.

After difficult negogiations CRAF and Iridium LLC reached agreement on substance which is formulated in the ESF-Iridium LLC Agreement for the period 1 May 1999 - 1 January 2006.

This agreement has no impact whatsoever on the protection of radio astronomy from 1 January 2006 as outlined in the ESF-Iridium LLC Framework Agreement

4. ESF Press Release

The Committee on Radio Astronomy Frequencies, CRAF, is an associated committee of the European Science Foundation, ESF. The ESF in its parent role published a press release where it explained the milestone reached.

5. Evaluation

The new European agreement guarantees radio astronomy low interference levels for up to 50% of the year, thus allowing Europe's extensive 1612 MHz research programmes to continue, with operational restrictions.

Unwanted emissions from the Iridium satellites are expected to be lowest during periods of low user traffic. The clear times of low interference which Iridium LLC is prepared to guarantee include overnight periods similar to those negotiated elsewhere, and also weekends. The weekends are particularly important as they cover 24 hours per day, thus allowing radio astronomers to study objects in any part of the accessible sky.

CRAF is happy to note that the new agreement between ESF/CRAF and Iridium LLC is in many respects better than similar agreements reached elsewhere in the world:
The situation in the USA is as follows

  • the NRAO-Motorola MoU (1994) gives protection to radio astronomy during the 4 hours of low traffic of the Iridium system;
  • the Arecibo-Iridium agreement (1998) is giving up to 8 hours protection to the radio astronomy observations at Arecibo, Puerto Rico (but on notification only!).
    In India radio astronomers are protected for up to 6 hours of Iridium 'quiet time'. It should also be noted that in Australia, there exists no agreement between radio astronomers and Iridium LLC. In Canada, there agreement on the condition that from 1 January 2006 the levels for detrimental interference as given in ITU-R RA769-1 must be respected by the Iridium system.

    Nevertheless, the "Iridium case" has set a bad precedent in several respects, which could threaten the future development of radio astronomy in particular and the acceptance of an international treaty as the ITU-R Radio Regulations in general.

    The allocation of the frequency band 1616-1626.5 MHz for space-to-Earth transmissions in the Mobile-Satellite Service, MSS, was made at the World Administrative Radio Conference 1992, WARC-92, of the ITU, before technical studies had been concluded on the possible harmful effects on radio astronomy operations in the band 1610.6-1613.8 MHz.

    In recognition of the danger, the WARC-92 explicitly added ITU-R footnote S5.372 to protect radio astronomy. Thus radio astronomy had regulatory protection. Yet in practice the radio astronomy measurements are now having to be squeezer into those times when Iridium LLC is willing to guarantee low interference levels. In effect, radio astronomy is time-sharing with the unwanted emissions (radio waste) of the Iridium satellites.

    Given the explosive growth in satellite telecommunications and broadcasting, radio astronomers are worried about the long-term 'threat' to their science from unwanted emissions of all these satellites. 80% of frequency bands allocated to the radio astronomy service on a primary basis are adjacent to a band allocated for space-to-Earth transmissions. The allocations are not yet taken up, in most cases, which is fortunate for radio astronomy.

    Some other points of attention are:

  • ITU-R footnote S5.372:
    Iridium supports the interpretation that protection is needed only during actual operations of the victim service. CRAF's view is that Iridium's opinion is not supported by the ITU-R Radio Regulations and the ITU Constitution. Because of this faulty interpretation, the USA agreements contain clauses that radio astronomy observations should be scheduled avoiding peak traffic periods of the Iridium system. Arecibo has even the obligation to show Iridium LLC its schedules. The new European agreement does not contain such a clause: it is the responsibility of each individual radio astronomy station to do the observations at the time it considers best to achieve the scientific goal.

    As was said in CRAF Newsletter 1998-3 CRAF shares the opinion that it is difficult to understand that radio astronomers are expected to sacrifice quality of observations, while the frequency channels from which the interference originates are outside the radio astronomy band 1610.6-1613.8 MHz and protection is guaranteed by ITU-R Radio Regulations footnote S5.372.

  • time sharing:
    the agreement is an implementation of a time-sharing scenario. However, it must be noted that according to ITU-R definitions, one cannot speak of a sharing situation: the frequency band of the victim service (i.e. radio astronomy) is 1610.6-1613.8 MHz and that of the interferer is (i.e. the Iridium system) is 1621.35-1626.5 MHz. A sharing situation occurs only when the victim services and the interfering service use rightly an allocation within the same frequency band. CRAF's concern is that a problem of interference due to unwanted emissions from a poorly designed transmitting system is cured by an improper tool: in this case time-sharing with 'radio waste'. Regulatory authorities should prevent such solutions in future to prevent improper evolution of the interpretation and use of the ITU-R Radio Regulations.

  • further work:
    following the ESF-Iridium LLC Framework Agreement, the new agreement contains a clause on collaborative efforts to discuss before 1 January 2006 "ways to reduce the susceptibility of radio astronomy observatories to interference from the Iridium Satellite System". In an annex to the agreement an initial workplan is given. This workplan will be adjusted according to the technological and scientific developments during the period of validity of the agreement.

    6. Abbreviations used in this Newsletter

    CEPT = Conference of European Post and Telecommunication administrations
    CRAF = Committee on Radio Astronomy Frequencies (ESF)
    ERC = European Radiocommunication Committee (CEPT)
    ESF = European Science Foundation
    ITU = International Telecommunication Union
    ITU-R = ITU Radiocommunication Sector
    MERLIN = Multi Element Radio Link Interferometer
    MRC = Milestone Review Committee (ERC)
    MSS = Mobile-Satellite Service
    NRAO = National Radio Astronomy Observatory (US)
    RDSS = Radio Determination-Satellite Service
    VLBI = Very Long Baseline Interferometry
    WARC = World Administrative Radio Conference (ITU)


    Last modified: June 2, 1999