1. The Arecibo Observatory
Emily Ducharme

2. The Telescope
The Arecibo Observatory contains the worlds largest radiotelescope.
The telescope itself is made up of a gigantic “dish” which is 305m in diameter and 167 feet deep.
The telescope is a spherical reflector whose surface is covered in perforated aluminum panels.
The actual focal structure and receiving equipment of the telescope are suspended 150m above the ground.
The “Gregorian” dome is located here.
“Gregorian” focus: the secondary reflector is placed behind the focal point of the primary reflector.
3 reflectors in this case: primary, secondary, tertiary.
Source: National Astronomy and Ionosphere Center. June, The 305 meter Radio Telescope. Last Access: Jan. 28,
Source: Cornell. The Arecibo Radiotelescope. Last Acess: Jan. 28, egg.astro.cornell.edu/alfalfa/ugrad/backgrnd/intro2arecibo.pdf

3. The Telescope Picture of Arecibo!
Source: Wikipedia;

4. The Telescope Specifications: Aperture: 305m
Angular Resolution: 1.22x10-3 radians or ̴ 4’
Observable Wavelengths: 3.00cm – 6m
Source: National Astronomy and Ionosphere Center. June, The 305 meter Radio Telescope. Last Access: Jan. 28,
Source: Cornell. The Arecibo Radiotelescope. Last Acess: Jan. 28, egg.astro.cornell.edu/alfalfa/ugrad/backgrnd/intro2arecibo.pdf

5. The Telescope Some instruments available for use:
3 Fabry-Perot Interferometers
1 Ebert-Fastic Spectrophotometer
2 Tilting-Filter Photometers
Nd: YAG Doppler Rayleigh LIDAR (Light Detection and Ranging)
Alexandrite Doppler Resonance LIDAR
2 Dye-laser (Resonance LIDARs)
Several transmitters available:
“S-band” 2380MHz transmitter
High frequency transmitter and mesh antennae
430(MHz) Antennae
Several receivers available also
430 antennae: study ionosphere
“S-band”: study planets (radar)
LIDAR: study upper and middle atmosphere
High f: active plasma experiments in ionosphere.
Source: Advanced Molecular Incoherent Scatter Radar Arecibo Observatory. Last Access: Jan. 28, amisr.suagm.edu/Information/arecibo.htm

6. History and Purpose Images of telescope!
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7. History and Purpose The construction of this telescope began in 1960.
The grand opening took place on Nov. 1, 1963.
The telescope is located in Arecibo, Puerto Rico.
At the equator: the whole sky is visible, can study the ionosphere and the planets.
Local terrain: sinkholes provide “natural geometry” in which the spherical reflector could be built.
Penn State Galaxy Interactions. Last Access: Oct. 16,
Source: National Astronomy and Ionosphere Center. June, The Arecibo Observatory. Last Access: Jan. 28,

8. History and Purpose
The telescope was originally constructed to study the ionosphere.
Now, it’s main use is to study areas within Radio Astronomy, Atmospheric Science and Radar Astronomy.
The Arecibo Observatory is part of the National Astronomy and Ionosphere Center (NAIC) and is operated by Cornell University.
It’s under a cooperative agreement with the National Science Foundation (NSF).
Source: National Astronomy and Ionosphere Center. June, The Arecibo Observatory. Last Access: Jan. 28,
Source: National Astronomy and Ionosphere Center. June, Areas of Research. Last Access: Jan. 28,

9. History and Purpose Applying for time:
One can request for time on this telescope.
Time is granted based on merit and promise of research.
This is decided by a panel of “independent referees” who review each proposal.
Deadlines for proposals: February 1st, June 1st, October 1st.
Equally open to all qualified observers regardless of their affiliation.
Source: Cornell. The Arecibo Radiotelescope. Last Acess: Jan. 28, egg.astro.cornell.edu/alfalfa/ugrad/backgrnd/intro2arecibo.pdf

10. Research and Results Asteroid fly-by
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11. Research and Results
Targets and projects undertaken by the Arecibo Observatory usually fall into three categories: Atmospheric Science, Radar Astronomy, and Radio Astronomy.
One will find studies within each of these areas taking place at the AO.
Under Atmospheric Science at the AO, one can:
Measure the composition, temperature, and the density of the upper atmosphere (understand controlling physical processes)
Measure the growth and decay of disturbances in the ionosphere (alt. above 30 miles).
Study plasma physics processes in Earth’s atmosphere.
Source: National Astronomy and Ionosphere Center. June, Areas of Research. Last Access: Jan. 28,

12. Research and Results
When it comes to Radar Astronomy, the following can take place at the Arecibo Observatory:
Study the celestial bodies in our solar system (ie. moons, planets, asteroids, comets)
Radio energy is transmitted, reflected, and collected by the telescope.
One can then study the surface features, composition, size, shape, rotation, and path of the target.
Source: National Astronomy and Ionosphere Center. June, Areas of Research. Last Access: Jan. 28,

13. Research and Results Radio Astronomy a very large focus of the AO.
One can detect faint radio emissions from distant regions of the universe.
The following projects have been/are being undertaken at the Observatory:
Continuum Observations
Pulsars
VLBI (Very Long Baseline Interferometry)
Spectral Line Observations
Continuum: Thermal radiation (hot gas) and Non-thermal radiation (synchrotrons: electrons in mag. Fields)
Spectral Lines: HI line, OH lines, CH, H2CO, methanol, etc.
Source: National Astronomy and Ionosphere Center. June, Areas of Research. Last Access: Jan. 28,
Source: Cornell. The Arecibo Radiotelescope. Last Acess: Jan. 28, egg.astro.cornell.edu/alfalfa/ugrad/backgrnd/intro2arecibo.pdf

14. Pulsars
Since the first pulsar was discovered, pulsar’s have been a large area of research at the AO.
Many discoveries involving pulsars have been made at the AO.
Relativistic Binary discovered in July 1974 by Russel A. Hulse and Joseph H. Taylor
A pulsar with a period of 59ms was found rotating another neutron star.
The orbit was 7.75 hours.
This strongly agreed with Einstein’s Theory of Relativity.
Only experimental evidence for Gravitational Radiation
This discovery won the 1993 Nobel Prize.
T of R: separation decreases 3mm each rotation, agreed.
Source: H. Heintzmann Pulsar Research at Arecibo. Last Access: Jan. 28, hera.ph1.uni-koeln.de/~heintzma/PSR1/PSR_NAIC.htm

15. Pulsars
The first millisecond pulsar was discovered at the AO by Don Backer and Shri Kulkarni in 1982.
PSR had a spin period of ms, rotating around it’s axis at almost 642 times per second.
Still the most rapidly rotating neutron star known.
Source: H. Heintzmann Pulsar Research at Arecibo. Last Access: Jan. 28, hera.ph1.uni-koeln.de/~heintzma/PSR1/PSR_NAIC.htm

16. Pulsars
The first extrasolar planetary system was found around a millisecond pulsar in 1992 at the AO by Alex Wolszczan and Dail Frail.
Presence of at least two Earth-mass bodies in orbit around the star.
Many surveys (like the ALFA – Arecibo L-band Feed Array – pulsar survey and the Arecibo Survey for Pulsars in Globular Clusters) are still taking place at the AO furthering the research in this area.
Source: H. Heintzmann Pulsar Research at Arecibo. Last Access: Jan. 28, hera.ph1.uni-koeln.de/~heintzma/PSR1/PSR_NAIC.htm

17. Pulsars Binary System: Pulsar orbiting a neutron star
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18. Study of Mercury
The Arecibo Observatory studied Mercury several times throughout it’s existence, making a few key discoveries:
It established the rotation rate of Mercury in 1965 (59 days opposed to previously believed 88 days)
In the 1990s, it investigated the ice craters and polar regions of Mercury with the radar system.
Created surface maps of Mercury (and Venus)
Source: National Astronomy and Ionosphere Center Arecibo Observatory Accomplishments. Last Access: Jan. 28,

19. Research and Results Radar image of Mercury’s North Pole.
Radar Data: The Moon
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20. References
National Astronomy and Ionosphere Center. June, The 305 meter Radio Telescope. Last Access: Jan. 28,
Cornell. The Arecibo Radiotelescope. Last Access: Jan. 28, egg.astro.cornell.edu/alfalfa/ugrad/backgrnd/intro2arecibo.pdf
Advanced Molecular Incoherent Scatter Radar Arecibo Observatory. Last Access: Jan. 28, amisr.suagm.edu/Information/arecibo.htm
National Astronomy and Ionosphere Center. June, The Arecibo Observatory. Last Access: Jan. 28,
National Astronomy and Ionosphere Center. June, Areas of Research. Last Access: Jan. 28,

21. References
H. Heintzmann Pulsar Research at Arecibo. Last Access: Jan. 28, hera.ph1.uni-koeln.de/~heintzma/PSR1/PSR_NAIC.htm National Astronomy and Ionosphere Center. June, Arecibo Observatory Accomplishments. Last Access: Jan. 28,

22. References - Images
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