1. GLONASS and Radio Astronomy R. J. Cohen R. J. Cohen Jodrell Bank Observatory University of Manchester Jodrell Bank Observatory University of Manchester 13th June 2002 13th June 2002

2. Outline of Presentation Historical background GLONASS – Radio Astronomy Joint Experiment Current status Outline of Presentation Historical background GLONASS – Radio Astronomy Joint Experiment Current status

3. GLONASS in the 1980s GLONASS was a big problem at a time of great interest in 1612MHz OH-IR sources (OH shells resolved 1981; IRAS catalogue published 1985) Transmissions overlapped 1612MHz OH line GLONASS artefacts seen through 0dBi sidelobes typically 5K (5Jy on 100m dish; 50Jy on 30m dish) Sensitivity eqn Rapid variations as satellites traverse sidelobes Null spikes look like masers (seen even at 1667MHz) More than 100MHz “occupied” Military “secret” so difficult to establish dialogue GLONASS in the 1980s GLONASS was a big problem at a time of great interest in 1612MHz OH-IR sources (OH shells resolved 1981; IRAS catalogue published 1985) Transmissions overlapped 1612MHz OH line GLONASS artefacts seen through 0dBi sidelobes typically 5K (5Jy on 100m dish; 50Jy on 30m dish) Sensitivity eqn Rapid variations as satellites traverse sidelobes Null spikes look like masers (seen even at 1667MHz) More than 100MHz “occupied” Military “secret” so difficult to establish dialogue

4. Lovell Telescope 250 ft fully steerable Prime focus 150MHz – 5 GHz Upgrade in progress

5. Interference from Satellites - I   Line of sight: can’t shield against them!   Global coverage: all terrestrial sites affected   Spread spectrum: radio pollution of passive bands   Many examples (GLONASS, Astra, Tex, Iridium, … )   Malfunctions are difficult to repair in space   Long timescale for change, once launched   More than 100 satellites launched per year   No pre-launch check on total emissions (environmental impact) Interference from Satellites - I   Line of sight: can’t shield against them!   Global coverage: all terrestrial sites affected   Spread spectrum: radio pollution of passive bands   Many examples (GLONASS, Astra, Tex, Iridium, … )   Malfunctions are difficult to repair in space   Long timescale for change, once launched   More than 100 satellites launched per year   No pre-launch check on total emissions (environmental impact)

6. Historical Landmarks 1968Discovery of OH-IR sources 1979OH 1612-MHz line given secondary allocation 1982 1982 First GLONASS satellite launched (military) 1983Coordination of GLONASS begins 1985 1985 Interference identified and published IRAS catalogue published (~10 4 OH-IR sources) 1991 1991 First IUCAF-GLONASS meeting 1992 1992 Worldwide experiment to test possible cures Radio astronomy band made primary 1993 1993 GLONASS-IUCAF Agreement signed in Moscow 2006Projected completion of “clean-up” plan Historical Landmarks 1968Discovery of OH-IR sources 1979OH 1612-MHz line given secondary allocation 1982 1982 First GLONASS satellite launched (military) 1983Coordination of GLONASS begins 1985 1985 Interference identified and published IRAS catalogue published (~10 4 OH-IR sources) 1991 1991 First IUCAF-GLONASS meeting 1992 1992 Worldwide experiment to test possible cures Radio astronomy band made primary 1993 1993 GLONASS-IUCAF Agreement signed in Moscow 2006Projected completion of “clean-up” plan

7. GLONASS-IUCAF Agreement Coordination is possible with radio astronomy 1993 onwards, no satellites in channels 16-20 1999 onwards, satellites confined to channels 1-12 New GLONASS frequency plan is needed Filters will be installed on GLONASS-M satellites, sufficient to protect 1660-1670MHz band GLONASS administration will investigate ways to fully protect 1612-MHz band and will communicate their proposed solution at a future meeting IUCAF will coordinate further joint experiments as needed GLONASS-IUCAF Agreement Coordination is possible with radio astronomy 1993 onwards, no satellites in channels 16-20 1999 onwards, satellites confined to channels 1-12 New GLONASS frequency plan is needed Filters will be installed on GLONASS-M satellites, sufficient to protect 1660-1670MHz band GLONASS administration will investigate ways to fully protect 1612-MHz band and will communicate their proposed solution at a future meeting IUCAF will coordinate further joint experiments as needed

8. Current Status and Prospects Last launch 1 st December 2001 7 operating satellites at 30 th May 2002 Only channels 1-12 used (since ~2000) No evidence of filters on new satellites New GLONASS administration in place IUCAF is gathering information on current levels of interference from GLONASS, deadline 1 st Nov 2002 Possible further negotiations and further joint experiment Complicated by newcomers: Iridium, Globalstar?, etc. Current Status and Prospects Last launch 1 st December 2001 7 operating satellites at 30 th May 2002 Only channels 1-12 used (since ~2000) No evidence of filters on new satellites New GLONASS administration in place IUCAF is gathering information on current levels of interference from GLONASS, deadline 1 st Nov 2002 Possible further negotiations and further joint experiment Complicated by newcomers: Iridium, Globalstar?, etc.