Transcript Pampa del Peñasco

Argentina and Brazil
A possible site to host the
SKA
M. Arnal, G. Dubner, E. Giacani, J. Lepine, H. Levato, R. Morras, E. Reynoso
AAA, 2005, La Plata
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)
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 far remote stations
Inner radius 150 km
Outer radius (at least) 3000 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 Core
0.5 km nominal radius
20% collecting area
Close pack
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
Geographical location of the core site
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
Satellite View
Pampa del
Peñasco
~12 km
Pampa del Medio
RFI Measurements
RFI measurement equipment
Ligthning rod
Data transfer system
Antennae tower
•Log Periodic 0.1 – 3.3 GHz
•Circular Horn 3.3 – 18.0 GHz
•Circular Horn 15.0 – 25 GHz
Twin diesel generator group
Control room
~ 12 km
SKA Site
CASLEO
~ 1260 km
IAR
N
W
Power (dBm)
Some RFI
Measurements
S
Frequency (MHz)
Core and Central region
Cordón del Medio (2800 m)
5 km
Pampa del
Peñasco
(2650 m)
Sierra del
Tontal
(4368 m)
Cordón de
los Naranjos
(3225 m)
CASLEO (2550m)
Five arm asymmetric configuration
Pacific Ocean
Bolivia
Uruguay
Atlantic Ocean
10% location
tolerance
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 simultaneously at 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
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)
Source Visibility
Taurus
Ophiucus
Galactic Centre
h =30o
Chamaeleon
Visibility (hours)
h=
Elevation limit (h)=20o
25o
Declination
(230,-55)
(210, 50)
(225, -50)
Source Visibility
Visibility (hours)
h=
Elevation limit (h)=20o
25o
h =30o
SMC
LMC
(305o, 0o)
Galactic Plane
Declination
(~72%)
(195o , 0o)
(54o, 0o)
Opportunities for co-observation with existing
(or future) ground-based facilities
CTIO
ESO
LCO
SOAR
VLT
GEMINI-S
Visibility (hours)
Altitude limit of 30o
SKA
ALMA
APEX
CBI
ASTE
Declination
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.
Water vapor content
Peak opacity at 210 GHz
Viewing CASLEO from the SKA site
CASLEO
Pampa del Peñasco
N
W
Power (dBm)
Some RFI
Measurements
S
Frequency (MHz)
West
South
North
East
uv coverage
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
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
Common sky among VLBA, VLA and SKA
Visibility (hours)
VLA
SKA
Altitude limit= 30o
VLBA
Declination
S4 scintillation index
S4 measures the standard deviation of the signal intensity normalized
by the average intensity (ground to geo-stattionary satellite)