CTIO Historic Highlights

Shortcuts to: 1950s 1960s 1970s 1980s 1990s 2000s 2010s




June, 1958:   Prof. Federico Ruttlant of the U. of Chile visits Yerkes Observatory and proposes a cooperative observatory project to Drs. Kuiper and Hiltner.

July 7, 1958:   Dr. Kuiper contacts Dr. Shane to explore possible AURA interest in the cooperative observatory.  AURA is not then in a position to consider the project.

Jan 8, 1959:   U. of Chicago applies to the U.S. Air Force for funds for a 40-inch telescope in Chile to be located near Santiago. The Air Force expresses interest and agrees to fund site testing program.

May-Jun 1959:   Dr. J. Stock, later CTIO's first Director, travels to Chile and with U. of Chile personnel and equipment, a site testing program is organized.  The first sites tested were near Farellones and Cerro El Roble.

June 1, 1959:   The Universities of Chile, Chicago, and Texas sign an agreement for a cooperative observatory to be funded by the U.S. Air Force. The 40-inch telescope project becomes a 60-inch telescope project.  Dr. Clemence suggests the project title:  "The Inter-American Observatory in Chile".

Aug 19, 1959:   Dr. I. Epstein of Columbia U. starts another site testing program in Chile with NSF funding.  This program aimed at comparing sites in Chile, Argentina, Australia, and South Africa. A month later Drs. Stock and Epstein coordinated their programs. Eventually, the U. of Columbia and Yale U. established an astrometric observing station near San Juan, Argentina.

Oct 19, 1959:   Dr. G. Keller of the NSF expresses the interest of the NSF in supporting the Chilean Observatory project. A policy advisory committee with AURA, NSF, Air Force, and Universities of Chile, Chicago, and Texas representatives is formed to consider the future of the project.

May 25, 1960:   AURA is asked to take over construction and operation of a "joint Chilean Observatory".

June 30, 1960:   AURA assumes reponsibi1ity of site surveys for U.S. observatory in Chile under the auspices of the U.S. Air Force and subsequently the National Science Foundation.

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Feb.Aug, 1960:   Site surveys extended northward to include Tololo, Morado, and other mountains near Vicuña.

August, 1961:   0.41-m telescope hauled to Cerro Tololo on mule back for tests of site.

December 1961:   AURA and the U. of Chile sign an agreement for establishment of the observatory in Chile.

December, 1961:   CTIO's first administrative office opens at the Chilean National Observatory at Cerro Calán, Santiago.

Oct 11. 1962:   Eight hectares lot is purchased in La Serena.

Nov 23, 1962:   Cerro Tololo chosen as site and the Observatory's current name adopted.

Nov 25, 1962:   AURA buys the property El Totoral, 30,000 hectares, with Cerro Tololo near its center.

Dec 2, 1962:   Traditional flag-raising ceremony held on Tololo in company of Chilean officials who climbed the mountain on horseback.

January, 1963:   Chilean Congress, with sponsorship of the U. of Chile, approves duty-free importations by AURA.  Such importations were to be handled by the U. of Chile.

February, 1963:   NSF approves the funding of a 0.92-m telescope for CTIO.

April 1963:   Dr. J. Stock is appointed first Director of CTIO.

Sept, 1963:   First vehicle driven to Tololo on the primitive, but passable, 38-kilometer access road.

Mid-1963:   "Temporary powerhouse, warehouse, and maintenance shops completed, and 25 years later, the "temporary" structures are still in use.

June 1963:   Representatives of ESO and AURA meet to discuss possibility of the European Southern Observatory being located in CTIO's grounds. In 1965 ESO decides on La Silla for its location.

Dec 63-Feb 64:   Dr. H. Babcock, director of Mt. Wilson and Palomar Observatories, visits CTIO to initiate a site survey on AURA's grounds for a Carnegie Southern Observatory. After initial tests at Cerro Pachón, further testing was limited to Cerro Morado.  Eventually the Carnegie Observatory is established on Las Campanas.

January 1964:   Construction initiated of the Headquarters building in La Serena.

February 1964:   First radio messages sent between CTIO and KPNO.  The University of Chile allowed CTIO to use its assigned wavelengths and call letters.

March 1964:   AURA Board approves five-year master plan for development of CTIO.

May 1964:   First 800 books acquired for Library.

Jan-Jun 1964:   Leveling of the top of Cerro Tololo carried out.

Mid-1964:   The U. of Chile, La Serena Branch, on a cost-free basis, allows CTIO to build an access road to CTIO's headquarters across its property.

June 1964:   Water being pumped to Tololo from a spring at Los Placeres.

July 1964:   Within weeks of leveling the summit of Tololo, housings started for the 0.41m, 0.92m, and 1.5-m telescopes.

June 30, 1965:   The CTIO staff consists of seven employees, two of which were stationed in Tucson, Arizona. By January 1976 when the 4-m telescope is put into operation the staff numbered 175. Currently (Dec 1987) it numbers 138.

December 1965:   First 50,000-gallon water storage tank installed on Tololo.

December 1965:   An additional hectare containing a house added to the La Serena compound at its western end (Calle Cisterna).

Mid-1966:   Five houses completed on Tololo.

Oct 26, 1966:   AURA concludes agreement with the University of Michigan to install the Curtis Schmidt telescope on Tololo on a 10-year loan basis; the agreement was extended for 25 years in 1975.

December 1966:   Ford Foundation decides to donate $5 million on matching-grant basis with NSF for construction of a 4-m telescope in the Southern Hemisphere.

April 1967:   At Punta del Este, Uruguay, U.S. President Johnson and Chilean President Frei jointly announce that the Ford-NSF 4-m telescope would be installed on

March 1967:   0.92-m telescope acquired and installed outdoors; moved to its permanent housing in Kay.

May 1967:   Housings for the 0.4l-m and 0.92-m telescopes are completed.

Sept 1967:   Previously planned houses on Cerro Tololo for the CTIO Director and a Mountain Superintendent, as well as three other houses, are eliminated from the Master Plan.

October 1967:   1.5-m telescope installed.

October 1967:   The administrative/scientific (round) office building is completed on Tololo.

October 1967:   Astronomers' Dormitory and Dining Hall first occupied.

Nov 3, 1967:   The U. of Chile and CTIO jointly sponsor a conference on Astrophysical Photometry in Santiago as part of the CTIO inauguration program.

Nov 6, 1967:   First light on the 1.5-m telescope.

Nov 7, 1967:   Official inauguration of CTIO.  The benediction is given by Msgr. Fresno, later Cardinal Fresno.  Chilean President Frei visits Tololo.

Nov 1967:   Tololo instrument shop completed; it subsequently becomes the electronic shop, and eventually the visitors' center.

April 3, 1967:   The housing for the Curtis Schmidt telescope is completed.

Late 1967:   Late in the year, the decision is made to locate in La Serena all CTIO service shops not needed on Tololo: e.g., the instrument shop, ETS offices and shops, the library, receiving warehouse, main garage and computer center.

December 1967:   Excavation started for 4-m telescope housing.

March 1968:   An additional eight hectares are added to the La Serena compound at its eastern end (hilltop). 

Mid-1968:   Negotiations initiated to modify importation procedures of CTIO shipments.

July 1968:   The first prefabricated houses for U.S. hired

Aug 7, 1968:   With AURA approval, the CTIO Director and the Rector of the U. of Chile sign an agreement allowing telescope time for U. of Chile astronomers.

December 1968:   The Government of Chile extends to CTIO's U.S. Hires certain benefits enjoyed by foreign employees of the United Nations branch office in Santiago.

March 1969:   Lowell 24-inch telescope installed.

May 21, 1969:   Harvard and Yale Universities and MIT plan possible installation on Cerro Morado of a 90-inch, a 36-inch, and a l6-inch telescope.

July 25, 1969:   The 4-m Cervit mirror blank is cast by Owens-Illinois Company of Toledo, Ohio. The l7-ton casting is the largest casting ever made.

September 1969:   Passage by the Chilean Congress of a law modifying importation procedures and freeing CTIO from certain taxations and limitations of its operations.

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June 1970:   The U. of Chile and AURA award the first jointly-financed fellowship for Chilean graduate students in Astronomy.

March 1971:   NASA, the U. of Chile, and the Smithsonian Institution install on Cerro Morado a station to observe barium clouds injected into the upper atmosphere by Germany's Max Planck Institute.

March 1971:   The U. of Chile puts into operation a seismograph station on Cerro Tololo.

March 1972:   4-m telescope housing completed.

June 1972:   Yale University agrees to lend its 1-m telescope to CTIO. The telescope is put into operation one year later.

Mid 1974:   A low wattage microwave relay station is erected on a side spur of Cerro To1o1o by the Chilean Telecommunications Agency, ENTEL, per agreement with AURA.

December 1975:   Completion of fine tuning of, and addition of the cassegrain secondary to the 4-m telescope.

Jan 1, 1976:   First visiting astronomers use the 4-m telescope.

1977:   At the request of CTIO, the Government of Chile declares Cerro Tololo a privileged scientific sanctuary where mining is prohibited without permission of the President of Chile.

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November 1982:   Columbia University starts operation at CTIO of a 1-m diameter, millimeter radio telescope.

November 1982:   The AURA Board of Directors agrees on a reorganization whereby CTIO becomes part of NOAO along with KPNO and spa. NOAO comes into existence officially on February 1, 1984.

January 1986: Dr. Robert Williams is appointed CTIO Director until July 1993.

February 23, 1987: Supernova 1987A explodes in the Large Magellanic Cloud (a satellite galaxy of the Milky Way). It is first naked eye supernova in four centuries, and sparks intense investigation with CTIO telescopes (e.g. Phillips et al. 1988).

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November 1993: Dr. Malcolm G. Smith is appointed CTIO Director until October 2003.

November 1993: In response to a request for guidance, CTIO receives advice from Senator Edgardo Boeninger that Chile is about to set up a Chilean equivalent of the US Environmental Protection Agency (CONAMA) and recommends putting CTIO's interest in protection against light pollution on its early agenda.

1997: The 1.3m (50-inch) IR survey telescope begins the southern component of the Two Micron All Sky Survey (2MASS), mapping the sky in the near-infrared, with sensitivity limits of J = 15.8, H = 15.1 and K = 14.3. The 2MASS survey produced a catalog of over 470 million infrared point sources (mostly stars), 1.6 million extended sources (mostly galaxies), and helped in detecting hundreds of the nearest substellar objects ("brown dwarfs") to the Sun.

1998: President Frei Ruiz Tagle signs the Supreme Decree 686/98, now more normally referred to as the "norma luminica", which provides a legal foundation for the effort to protect astronomy in northern Chile. This action probably gained an increase of a couple of decades in the useful future lifetime of the sites in northern Chile for astronomical research.

December 18, 1998.  Science Magazine recognizes discovery of the accelerating universe as the Science "Breakthrough of the Year" for 1998. Given the then wide-field capability of the telescope the clear dark site and efforts to maintain pixel-limited imaging performance, much of the early work by the two main groups who made the discovery was carried out on Cerro Tololo at the Blanco 4m telescope. Important calibration work for using Type Ia supernovae as distance indicators was carried out by CTIO staff in Calan/Tololo supernova survey with the Michigan Curtis Schmidt telescope (e.g. Hamuy et al. 1996). In the Riess et al. 1998 study demonstrating the existence of the dark energy, the 10 Type Ia supernovae analyzed with redshifts 0.16 < z < 0.62 were all discovered with the prime-focus CCD camera on the Blanco 4-m telescope.

August 1999.  Event "The Sun, Our Star" heralds the formation of a local schools network "RedLaser" and organized local public outreach from Cerro Tololo.

October 1999.  The "norma luminica" Chilean law to protect the future of astronomy in northern Chile (DS 686/98) comes into force.


2000: Michigan State University becomes a partner in the SOAR 4.1m telescope, finalizing the partnership formation process led with tenacity and patience by the University of North Carolina.  It took UNC 18 years to get the telescope built after multiple partners had bowed out.

2000: Given the greater medium-term risk of light pollution at Cerro Tololo and Cerro Pachon, the national office for the protection of the skies of northern Chile (OPCC) is set up and the former Regional director of CONAMA is hired as the first director of the OPCC.

March 2002: International Conference on Light Pollution held in La Serena.

November 2003: Dr. Alistair R. Walker is appointed CTIO Director until October 2008.

April 17, 2004: Dedication ceremony for the SOAR 4.1m telescope held on Cerro Pachon. 

2006: In response to increasing pressure on CTIO to reduce its support of the small telescopes on Cerro Tololo, the community-led SMARTS consortium - set up a few years earlier to provide balance for the installation of Gemini South and SOAR on Cerro Pachon - begins operation of the SMARTS telescopes (0.9m, 1.3m, 1.5m).

May 17, 2006: El Peñón summit on Cerro Pachón is selected as the future site for the 8.4-m Large Synoptic Survey Telescope (LSST).

November 2008: Dr. Robert C. Smith is appointed CTIO Director.


2011: In the context of humanity's ability to see dark skies in the future and carry out optical observational astronomy from the ground, Cerro Tololo and Cerro Pachon are highlighted as case studies in the IAU/ICOMOS/UNESCO World Heritage Centre book on Heritage Sites of Astronomy and Archeoastronomy as a potential World Science Heritage Centre (along with sites in Hawaii, La Palma and South Africa).

March 8, 2011: LSST "first blast": initiation of site leveling of the El Peñón summit of Cerro Pachón in preparation for the LSST.

October 4, 2011: 2011 Nobel Prize in Physics won by three astronomers, for the discovery that the expansion of the Universe is speeding up. Saul Perlmutter (Lawrence Berkeley National Lab) led the Supernova Cosmology Project while Brian Schmidt (Australian National University) and Adam Riess (Johns Hopkins/Space Telescope Science Institute) were leading members of the High-z Supernova Search team. Present (Chris Smith) and past (Mark Phillips, Nick Suntzeff, Mario Hamuy, Bob Schommer) CTIO staff members were members of the High-z team. Both teams announced their results in 1998. Both teams used the Blanco 4m telescope and prime focus imagers in the period 1994-1998 for some of their most critical observations. And prior to this, important precursor observations were made on the Curtis Schmidt telescope by Mario Hamuy and Jose Maza (U. Chile). CTIO staff, both scientific and technical, were crucial in providing the support that allowed these very difficult observations to be made successfully. At that time, the Blanco telescope plus Big Throughput Camera was the most powerful CCD camera in the world. The unexpected discovery that the expansion of the universe is speeding up led to the concept of "dark energy" and that the Universe we see (stars etc) represents only a very minor constituent of the mass-energy budget of the universe.

2012: Commissioning scheduled for the Dark Energy Camera (DECam) wide-field imager on the Blanco 4-m, and the anticipated start of the Dark Energy Survey - a comprehensive program to characterize the evolution of the dark energy over cosmological time.

October 1, 2012: Dr. Nicole van der Bliek is appointed CTIO Director.

November 23, 2012:   50th anniversary of Cerro Tololo Inter-American Observatory!

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