Protecting the RF environment at the Cerro Chascón Science Preserve Guillermo Delgado European Southern Observatory

La Serena 07/03/02 Millimeter astronomy

La Serena 07/03/02 Guglielmo Marconi ( )

La Serena 07/03/02 ITU and the international frequency spectrum regulation The International Telecommunication Union (ITU) was created in 1865 and today is an specialized agency of the UN ITU issue treaties after WARCs or can issue recommendations. As all cases of International Law, the countries have sovereign privileges within their borders ITU recommends, the local administrations can accept or not. The good-will of the local administrations is fundamental

La Serena 07/03/02 Radio astronomy as a radiocommunication service Recognised as a radiocommunication service by ITU at the WARC of 1959 Represented at ITU by the Inter-Union Commission for the Allocation of Frequencies for Radio Astronomy and Space Science – IUCAF – (IAU, URSI, COSPAR), has no voting rights Passive service

La Serena 07/03/02 ITU recommendations Interfering signal are all those unwanted signals exceeding in 10% the sensitivity of the system (ITU-R RA.769-1) The local authorities are reminded that it is very difficult for the radio astronomy service to share frequencies with other services (ITU-R RA.769-1) It is suggested to create “coordination zones” for transmitters (ITU-R RA )

La Serena 07/03/02 International protection of radio astronomy There are some frequency bands assigned internationally for the radio astronomy service: Assigned as primary service shared with other passive services Assigned as primary service shared with other active services Assigned as secondary service

La Serena 07/03/02 Telecommunication authority in Chile Jaime Etcheberry Secretary of Infrastructure, transport and telecommunications Ricardo Lagos President of Chile Christian Nicolai Sub-secretary of Telecommunications Patricio Tombolini Sub-secretary of Transport Juan Carlos Latorre Sub-secretary of Infrastructure

La Serena 07/03/02 Atacama Large Millimeter Array (ALMA) Scientific Preserve of Cerro Chascón, 5000 m altitude, 60 km NE of San Pedro de Atacama 64 antennas 12 m diameter Collecting area ~ m 2 Surface accuracy < 25  m Baselines 18 to m Resolution comparable to the Hubble Space Telescope Operating frequency 30 to 950 GHz Bandwidth 4 GHz

La Serena 07/03/02 ALMA sensitivity Using ITU criteria (Handbook on Radio Astronomy, ITU-R RA.769-1) and ALMA parameters (Antenna diameter 12 m, frequency 230 GHz, bandwidth 8 GHz, integration time 2000 s, T sys 80 K) we obtain a sensitivity at the antenna aperture of 600  Jy 1 Jansky (Jy) = W m -2 Hz -1

La Serena 07/03/02 ALMA location

La Serena 07/03/02 Llano de Chajnantor

La Serena 07/03/02 Frequency bands required by ALMA Band No.Frequency range [GHz] 131,3 – – – – – – – – –

La Serena 07/03/02 What have been done internationally to protect against radio interference at the radio astronomy stations Local assignment of frequency bands attributed to other services Radio quite zone around the radio astronomy stations (small geographic area) Coordination zone around the radio astronomy stations (large geographic area)

La Serena 07/03/02 Our proposal to achieve protection against radio interference at Chajnantor Local assignment of the ALMA required frequency bands (small geographical area)  SUBTEL Creation of a coordination zone around Chajnantor (larger geographical area)  SUBTEL Radio quite zone around the radio astronomy stations (small geographical area)  ¿CONAMA?, ¿SUBTEL?,

La Serena 07/03/02 What we have done Made a presentation at SUBTEL of the ALMA project and our protection request to the Subsecretario and other technical managers Obtained a compromise of collaboration from SUBTEL and created a joint working group Produced a 52 pages document about the need of RFI protection, including legal background and protection precedence in other countries. This document was used in our presentation at SUBTEL

La Serena 07/03/02 What we still need to do Complete technical data requested by SUBTEL to define the size of the coordination zone Obtain a formal recognition from SUBTEL to avoid future policy changes Educate the general public (and the politicians) about radio astronomy and the need to protect the observing environment

La Serena 07/03/02 Other astronomical projects at the Chajnantor area Cosmic Background Imager (CBI), Caltech Mobile Anisotropy Telescope (MAT), Princeton Millimeter Interferometer (MINT), Princeton Atacama Pathfinder Experiment (APEX), MPIfR, ESO, NSF Atacama Submillimeter Telescope (ASTE), NAOJ Infrared telescopes – University of Tokyo Atacama Observatory (TAO) – Cornell Atacama Telescope (CAT)

La Serena 07/03/02 End of the talk Sorry for talking so much! Questions?