Argentina and Brazil A possible site to host the SKA

1. Argentina and BrazilA possible site to host the SKA M. Arnal, G. Dubner, E. Giacani, J. Lepine, H. Levato, R. Morras, E. Reynoso AAA, 2005, La Plata

2. Configuration of the SKA The SKA will have 1 million square meters of physical collecting area distributed in a) Large number of small size receptors (LNSD) b) Small number of large size receptors (SNLD)

3. Schematic distribution of the SKA collecting area SKA near remote stations Inner radius 2.5 km Outer radius 150 km 24% collecting area Our log spiral SKA central area Inner radius 0.5 km Outer radius 2.5 km 32% collecting area 5-arm symmetric log spiral SKA far remote stations Inner radius 150 km Outer radius (at least) 3000 km 24% collecting area Our log spiral SKA Core 0.5 km nominal radius 20% collecting area Close pack

4. Initial Site Analysis Document • Radioquietness of potencial sites • Technical and scientific resources of the country • Physical characteristic of the site • Tropospheric and ionospheric conditions • Capital and operating costs • Political and economic situation of the region

5. Geographical location of the core site 98 km

6. CENTRAL SITE Province of San Juan, Argentina Altitude ~ 2550m above sea level λ= 69o 16‘ 18“ W; φ= -31o 42‘ 21" Pampa del Peñasco CASLEO Pampa del Medio

7. Satellite View Pampa del Peñasco ~12 km Pampa del Medio RFI Measurements

8. RFI measurement equipment Ligthning rod Data transfer system Antennae tower Control room Twin diesel generator group • Log Periodic 0.1 – 3.3 GHz • Circular Horn 3.3 – 18.0 GHz • Circular Horn 15.0 – 25 GHz ~ 12 km IAR SKA Site CASLEO ~ 1260 km

9. Some RFI Measurements N Power (dBm) W S Frequency (MHz)

10. Core and Central region Pampa del Peñasco (2650 m) 5 km Sierra del Tontal (4368 m) Cordón del Medio (2800 m) Cordón de los Naranjos (3225 m) CASLEO (2550m)

11. Five arm asymmetric configuration 10% location tolerance Bolivia Paraguay Chile Pacific Ocean Uruguay Atlantic Ocean

12. To measure the performance of the proposed configurations Figures of Merit (FOM) will be evaluated • Sky Visibility The SKA visible sky is defined as the sky that is above the 30o elevation limit simultaneouslyat all stations in the proposed array, for at least 4 hours a day • UV coverage The FOM will be: a) The weight as a function of radius in the uv plane b) The ¨circularity¨of the uv-coverage c) The percentage of empty uv-cells as a function of radius • Beam shape

13. Five Key Science Projects (KSPs) (or a list of key astronomical sources that NEED to be considered) • At least two of the three nearest dark clouds (Taurus, Ophiucus, Chamaeleon) (KSP 1 ) • Coverage of at least 70% (including Galactic Centre) between 235o ≤ l ≤ 125o ( KSP 1, 2, 3) • ~20.000 sq.d. of the sky out of the galactic plane, including the coldest regions of the sky and HI fluctuations (KSP 4, 5)

14. Source Visibility Elevation limit (h)=20o h= 25o h =30o Visibility (hours) Galactic Centre Ophiucus Chamaeleon Taurus Declination (230,-55) (210, 50) (225, -50)

15. Source Visibility Elevation limit (h)=20o h= 25o h =30o Visibility (hours) SMC (~72%) (305o, 0o) Galactic Plane (195o , 0o) LMC (54o, 0o) Declination

16. Opportunities for co-observation with existing (or future) ground-based facilities CTIO ESO LCO SOAR VLT GEMINI-S Altitude limit of 30o SKA Visibility (hours) ALMA APEX CBI ASTE Declination

17. Conclusions • The SKA will have unique scientific capabilities and it will open up a new era in scientific research. • The chosen core site, CASLEO, has low amount of RFI, low atmospheric opacity at high frequencies, and is located within a region with very low population density. It is not expected a significant change in the future. • Easy access by road. Relatively close to major urban centers. Overall weather conditions are unlikely to impact on the operation of the central SKA region. • The longest baselines will be provided by stations located in Brazil. • The proposed SKA layout fullfills the requirements of the KSPs and will be able to carry out simultaneus observations with existing (or future) major ground-based observing facilities • Strong commitment of the Federal and local governments, academic institutions and science related Federal agencies. • The SKA is a multi-millon dollar project. Our bid to host it, represents a low risk-high return investment. Involvement of our scientific and technical communities. • The location of the SKA in our countries will give a tremendous boost to the scientific activity and will bring many economic (participation in major infrastructure and enginering contracts for the construction of the SKA and resultant spins-offs into other applications) and other benefits.

18. Water vapor content Peak opacity at 210 GHz

19. Viewing CASLEO from the SKA site CASLEO Pampa del Peñasco

20. Some RFI Measurements N Power (dBm) W S Frequency (MHz)

21. North West East South

22. uv coverage

23. Collaborators • National Army Geographical Service • (cartography, geo-referenced satellite images) • Researchers of different fields of the CONICET, UNLP and UNSJ • (geographers, geologists, meteorologists) • (population geography. spatial analysis, spatial planning) • National Commision of Communications (CNC) • J. Benedetti • S. Sassonne • D. Sanchez • R. Plastina

24. The Argentinean candidacy has the endorsement of: • The National House of Representatives • The National Secretary of Science and Technology • The Board of Directors of the National Research Council of Science • and Technology • The Government of the Province of San Juan • “Consejo Académico” of the Faculty of Astronomy of the UNLP • “Consejo Superior” of the National University of La Plata

25. Common sky among VLBA, VLA and SKA VLA SKA Visibility (hours) Altitude limit= 30o VLBA Declination

26. S4 scintillation index S4 measures the standard deviation of the signal intensity normalized by the average intensity (ground to geo-stattionary satellite)