THE FUTURE OF THE ARECIBO 305 m TELESCOPE Don Campbell
NAIC/NRAO Single Dish Summer School July 17, 2009
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The keys to success for any organization: A first class product
The willingness/ability to innovate If these conditions are met the
customers will come.
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How does this apply to the Arecibo 305 m telescope? Telescope
is old but a great product combined with a long history of
innovative improvements to the telescope and its instrumentation
that has kept it at the forefront of research in astronomy and
atmospheric sciences.
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1963 Primary objective Incoherent scatter radar measurements of
ionospheric parameters electron density, temperatures, winds,
composition as function of altitude Made steerable spherical
antenna to allow: Radar studies of terrestrial planets and the Moon
Radio astronomy Characteristics: Maximum frequency 600 MHz - set by
the accuracy of the mesh surface Expected lifetime ~ 10 years BUT
Structure of telescope very well designed and constructed Telescope
completed in 1963
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Major achievements in radio and radar astronomy 1963 - 1973:
Measurement of the rotation periods of Mercury and Venus Search
for, and study of, pulsars Arecibo perfect telescope for this. 6 cm
wavelength sky survey BUT Could not observe the spectral line of
atomic hydrogen at 1.420 GHz. Lots of good science but not central
to then current community interests so waning support by radio
astronomers except for pulsar search and timing.
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1972 1974 Wire mesh surface replaced by 38,000 aluminum panels
~3 mm surface accuracy achieved => max freq of ~ 6 GHz 0.5 MW
transmitter installed at 3.8 GHz for solar system studies First
large (1008 channels, 10 MHz bandwidth) digital correlator for
spectral line observations.
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Some major results: Discovery of the first binary pulsar,
PSR1913+16 in 1974, leading to the (indirect) confirmation of
gravitational radiation and the Nobel Prize for Joseph Taylor and
Russell Hulse in 1993 First high resolution view of the surface of
Venus Mapping of the distribution of galaxies in the nearby
universe from HI observations Discovery of the first millisecond
pulsar Discovery of the first planets about another star a pulsar
Discovery of the first OH mega masers First high resolution images
of a NEA
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Early 1980s how to overcome limitations due to line feeds? Line
feeds: Intrinsically narrow band so need to build new one for every
frequency Geometric optics determines length but wavelength
determines size and spacing of radiating slots plus waveguide
diameter Not possible to build line feeds above ~ 3 GHz due to
tolerance issues but reflector surface probable usable up to 10 GHz
Significant reduction in Aeff/Tsys at high zenith angles Solution:
Do spherical aberration correction with mirrors - wavelength
independent
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Spherical reflector optics
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Gregorian Optics
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Gregorian Upgrade 1993 1997 1 Ground Screen to reduce spillover
noise 2 New drive systems including active tie-downs 3 Replace line
feeds with a reflector feed system 4 New receivers 5 New S-band
transmitter with twice the power 6 Improve surface accuracy of
reflector to reach 10 GHz Gregorian Upgrade 1993 1997 1 Ground
Screen to reduce spillover noise 2 New drive systems including
active tie-downs 3 Replace line feeds with a reflector feed system
4 New receivers 5 New S-band transmitter with twice the power 6
Improve surface accuracy of reflector to reach 10 GHz RESULT: A
modern telescope with greatly improved capabilities
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Was the Gregorian upgrade enough? Needed better instrumentation
to utilize the new capabilities. Result: The Arecibo L-Band Feed
Array (ALFA) and new spectrometers ALFA Receiver MOCK
Spectrometers
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Major results from the Gregorian Upgrade and ALFA: The ALFA
galactic and extra-galactic surveys Discovery of binary and triple
near-Earth asteroids (NEAs) Verification of the Yarkovsky and YORP
effects via near-Earth asteroid astrometry Discovery of
cm-wavelength molecular lines in ARP 220 and other ULIGS Discovery
of a neutron star (pulsar) with a mass of ~1.7 solar masses
allowing constraints on the equations of state of ultra dense
matter Participation in VLBI observations where the processing is
done in real time e-VLBI. And many more
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40 years of innovation has kept the 305 m telescope
contributing at the forefront of astronomical research WHAT
NEXT
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Keeping Arecibo at the forefront - Current and future projects
Ionospheric interaction facility: Basically plasma research
studying non-linear effects in the ionospheric plasma. Project cost
~$2M MAJOR INSTRUMENTATION PROJECTS Six transmitters at 5 and 8
MHz
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MAJOR INSTRUMENTATION PROJECTS 12 to 18m Antenna Research:
Phase reference antenna for VLBI at X-, C- and L-bands Potential
use for geodetic VLBI at X- and S-bands Education: Support local
education programs Remotely controlled antenna for student use
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12 or 18 m antenna for VLBI phase referencing 12 m Patriot
prime focus antenna at site of 64 m Parkes telescope, Australia
Cost ~$600k Potential site of the antenna at Arecibo
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Science Drivers for high sensitivity, high angular resolution
VLBI: Neutron Star Astrometry: - Measuring astrometric parameters:
position, proper motion, trigonometric parallax. - Proper motions
yield the identification of birth sites, independent age estimates
and velocity determinations (in combination with distances)
allowing tests of models for the natal kicks. - Parallaxes provide
model-independent distance estimates, testing suggested
associations with SNRs, stellar clusters, runaway stars, etc. Young
Supernova Remnants: - Imaging giving angular expansion and
deceleration rates for young SNRs Gamma-ray Burst Afterglows: -
Measurements of angular expansion and deceleration rates for GRB
afterglows allowing evaluation of the surrounding environment.
Proper motion measurements can be used to examine the importance of
jet emission.
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What will follow the ALFA 7-beam 21 cm system? Beam forming
focal plane array at 21 cm 40 beams on the sky will give very high
survey speed FY2009 start on developing specifications and
feasibility/design study meeting next week in Ithaca Do work in
cooperation with other groups in US and Canada with input from
Australian and European groups MAJOR INSTRUMENTATION PROJECTS
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Arecibo L-Band Feed Array
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ALFA 7-beam footprint on the sky - field of view is only
sampled in certain locations, it is not fully sampled. To maximize
the information that can be obtained by a given telescope about the
sky brightness distribution, measurements should be made every half
beamwidth. This cannot be done with a cluster of horns like the
7-horn ALFA system. Calculated beam pattern on skyMeasured beam
pattern
Survey speed of a telescope a figure of merit if you want to do
a blind survey of a large section of sky looking for e.g. galaxies
with detectable amounts of atomic hydrogen is given by:
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Survey Speed: Enter AO40 # of beams Bandwidth Beam Solid
Angle
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19 Dipole system under test at NRAO Green bank by Brigham Young
University and NRAO groups. 300 MHz bandwidth systems being
developed by the Australian SKA project for the ASKAP array and by
the Dutch for installation on the Westerbork Array. Australian
ASKAP checkerboard array
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Survey Speed Figure of Merit (A e ) 2 (Tsys) 2 FoVBWFoM
AO111111 ALFA11/1.473*14* AO4011/440330 APERTIF1/411/41800333
ASKAP1/1701/48800336 Assumes Tsys of 50K for Phased Array
Feeds.
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Arecibos AO40 Architecture Components 1.Gregorian Optics
2.Array Elements 3.LNAs 4.Cryogenics 5.Signal Transport 6.Beam
Former 7.Spectrometer A very complex task ! Figure by G.
Cortes
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Major science drivers for the AO40 Phased Array Feed: Very high
sensitivity survey of the local universe for HI haloes High
sensitivity mapping of the Galaxy in HI Continuum full Stokes
polarization mapping of the sky Deep search for pulsars
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MAJOR INSTRUMENTATION PROJECTS Wide-band 300 MHz to 3 GHz feed
development by German Cortes (NAIC, Ithaca) Potential use on the
305 m telescope Potential use of 1 to 10 GHz version for the 12-18
m VLBI antenna Potential use for the SKA
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MAJOR INSTRUMENTATION PROJECTS Arraying of the WAPP and MOCK
spectrometers for use with a single pixel feed to give very high
resolution spectra over 1 GHZ or larger bandwidths. Major
application to: Search for cm wavelength molecular line from
external galaxies Search for cm wavelength molecular lines in our
own galaxy Upgrading of VLBI recording instrumentation Expanding
the IF bandwidth
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Education and Public Outreach ~100,000 visitors each year
Strong K-12 educational effort through the Inspiration for Science
contract with the Puerto Rican Dept. of Education Proposal to the
Dept of Education for a teacher training program in preparation
Proposals to the NSF in conjunction with the University of Texas at
Brownsville for new displays, etc Expansion of the visitor
experience at the Observatory Expansion plans for the Angel Ramos
Visitor Center
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Arecibo has a lot going for it: Most sensitive single dish
radio telescope at frequencies up to 8 GHz - five times more
sensitive than the GBT Very modern instrumentation Very diverse
programs and capabilities in: Radio astronomy Solar system studies
Atmospheric science A proposal over subscription rate of 3 to 4 A
great staff
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Major problems: NAIC Facing significant budget reductions over
the next two years