The National Astronomy and Ionosphere Center (NAIC), whose principle research and educational facility is the Arecibo Observatory in Puerto Rico (Figure 1), was managed by Cornell University under a Cooperative Agreement (CA) with the National Science Foundation from October 1, 2005 to September 30, 2012 with its management of the Arecibo Observatory ceasing as of September 30, 2011. NAIC’s function was to facilitate and promote research at the Arecibo Observatory in the areas of radio astronomy, planetary sciences and the study of the Earth’s upper atmosphere, the ionosphere. Research programs are carried out primarily by external users from the United States and the world based on peer-reviewed proposals. Radio astronomy: Most research activities revolved around large-scale surveys conducted with the first multi-pixel cm-wavelength radio camera on a U.S. telescope, the 7-pixel Arecibo L-Band Feed Array (ALFA). Several spectrometer systems allowed multiple surveys to be conducted simultaneously with the only restriction that they had to observe the same locations on the sky greatly increasing the efficiency with which the telescope was utilized. Arecibo’s high angular resolution, tremendous sensitivity and first-class instrumentation and data handling capabilities plus the ALFA receiver system, enabled the most sensitive and highest spectral resolution 21-cm wavelength surveys carried out to date. They included the mapping of the entire local sky in the 21-cm HI emission line of atomic hydrogen, blind searches for HI in external galaxies, studies of HI in large high-Z galaxies, a spectro-polarimetric continuum survey aimed at a better understanding of cosmic magnetism, a search for new pulsars and a radio recombination line survey. Good proposals for non-survey science continued to be supported and included an energetic Very Long Baseline Interferometry program in conjunction with other radio observatories, the detection of organic molecules in external galaxies, and a major role in the North American Pulsar Timing Array aimed at detecting gravitational waves. Planetary science: A high power transmitter on the Arecibo telescope makes it the world’s most powerful radar system. It is used for studies of the terrestrial planets, satellites of Jupiter and Saturn, asteroids and comets. Major advances in our knowledge of the solar system included the mapping of ice deposits at the poles of Mercury (Figure 2), the search for ice deposits at the poles of the Moon, the study of the radar scattering properties of the surfaces of the Moon and Mars, and imaging and astrometric observations of near-Earth asteroids leading to precise predictions of their future orbits and detailed models of their size and shape. Outcomes: At least 440 papers describing research carried out at the Arecibo Observatory in the areas of radio astronomy and planetary studies were published in refereed journals over the period of the CA. A total of 40 doctoral theses were also completed. Instrumentation and infrastructure: Instrumentation projects included the acquisition of multiple spectrometer systems for use with the ALFA receiver, new receivers at other wavelengths, upgrades of the VLBI systems, a new pulsar timing system, and the installation of a 12-m antenna for enhancing VLBI capabilities and local educational programs. Infrastructure activities included painting 75% of the telescope and installing new safety lines, installation of four 1 MW diesel generators to provide power to the transmitters, new water and fuel tanks, new air conditioning systems, upgraded telephone systems and the construction of a new engineering office building. Education and public outreach: Each of the CA NAIC conducted a summer student program at the Arecibo Observatory. This very successful program (Figure 3) included NSF supported REU students, LSAMP (Louis Stokes Alliance for Minority Participation) funded students through the University of Puerto Rico (UPR), NAIC funded students and students funded by other institutions plus, in 2009 and 2010, local teachers under the RET program. A total of 74 students and 2 local teachers participated in the program. Starting in 2009, Cornell/NAIC also initiated a Coop Student program with UPR Mayaguez, an engineering campus. This was a very successful program that benefited both the students and the Observatory. The Angel Ramos Visitor Center and its adjunct Learning Center (Figure 4), built by Cornell with support from the Angel Ramos Foundation plus other private gifts, was the most successful of the modern visitor centers at the National Astronomy Centers. During the period of the CA it consistently attracted almost 100,000 visitors a year comprised of school children, local residents and off-Island tourists. About 30,000 students visited each year in organized school groups. The Visitor and Learning Centers provided the capability to hold numerous scientific workshops including ones with an emphasis on undergraduate students and faculty from small colleges. The NAIC/National Radio Astronomy Observatory Single Dish Summer School was initiated by NAIC and takes place every two years, alternating between Arecibo and NRAO’s Green Bank site.
