The Arecibo Observatory and its Telescope

The Arecibo Observatory (AO) is part of the National Astronomy and Ionosphere Center (NAIC), which is operated by Cornell University under a cooperative agreement with the National Science Foundation (NSF). Use of the AO is available on an equal, competitive basis to all scientists from throughout the world to pursue research in radio astronomy, radar astronomy and atmospheric sciences. Observing time is granted on the basis of the most promising research as adjudicated by a panel of anonymous referees.

Table: Basic Information on the AO Site and the 305-m Telescope

Site
Longitude (Geodetic)	66$^{\circ}$45$^{\prime}$11.1 $^{\prime\prime}$ W
Latitude	18$^{\circ}$20$^{\prime}$36.6 $^{\prime\prime}$ N
Elevation of reflector center of curvature	497 m (1630 ft) above MSL
Telescope
Primary Reflector
Diameter of Spherical cap	305 m (1000 ft)
Radius of Curvature	265 m (870 ft)
Illuminated Area (at zenith):
Gregorian Feeds	$213 \times 237$ m ( $700 \times 776$ ft)
430-MHz Line Feed	305 m (1000 ft)
Surface Accuracy	2 mm (rms)
Frequency range	300 MHz $< \nu <$ 10 GHz (Gregorian)
Wavelength range	1 m $> \lambda >$ 3 cm (Gregorian)
Slew Rates:
Azimuth	24$^{\circ}$/min
Zenith Angle	2$^{\circ}\!\!$.4/min
Pointing Limits:
Azimuth	0$^{\circ}$-720$^{\circ}$
Zenith Angle	0$^{\circ}$-19$^{\circ}\!\!$.7
Declination range	$-1^{\circ}20^{\prime} < {\rm Dec} < +38^{\circ}02^{\prime}$
Pointing Accuracy	$\sim$5 $^{\prime\prime}$ (rms)

The Observatory is located in the karst hills of the Caribbean island of Puerto Rico, some 10 miles south of the coastal city of Arecibo. It was constructed in 1960-63 and upgraded, first in 1972-74, and again in 1992-98. Table 1 lists basic information on the observatory site and the telescope. The Arecibo 305-m telescope is a general-purpose meter-to-centimeter wavelength instrument. Among its many possibilities, it supports the following types of investigation;

• spectral line observing, both ``pointed'' observations at specific targets, and ``on-the-fly'' mapping,
• continuum observing in total-intensity or full-Stokes mode. Beam switching is not presently available at any frequency,
• pulsar observing, including pulsar search (targeted and survey), timing measurements, single-pulse studies, investigations of interstellar scintillation, and polarization measurements,
• VLBI observing as part of all the major VLBI networks (i.e. HSA, EVN and Global). Recording is currently made via a VLBA4 data-acquisition rack and a Mk5A recorder,
• planetary radar observing, and,
• atmospheric physics investigations.

Neither planetary radar nor atmospheric physics will be specifically mentioned in this document (though some of the information included here may be of use to interested parties). Those requiring more details of the instruments available for such studies are directed to http://www.naic.edu/~pradar/pradar.htm for planetary radar studies, and http://www.naic.edu/aisr/sas/sashomeframe.html for atmospheric physics.

Additional information for all users can be found on the NAIC web site, http://www.naic.edu, including;

• road maps (http://www.naic.edu/public/mapmenu.htm),
• lodging fees +http://www.naic.edu/science/usrweb/general/visiting.htm#roomrates),
• telescope schedules (http://www.naic.edu/vscience/schedule/scedfra2.htm).