In the 12 months ending 31 July 1999, 186 observing programs were carried out at CTIO. These involved 418 scientists (207 observers and 211 collaborators) from 86 US and foreign institutions. In the same period, 153 papers were published based on research using Cerro Tololo facilities.

US Institutions (52)
Arizona State U.
Barnard College
Bates College
Bell Labs
Calif. Inst. of Technology
Carnegie Mellon U.
Carnegie Observatories
Columbia U.
Drew U.
Harvard-Smithsonian CfA
Indiana U.
Johns Hopkins U.
Lawrence Livermore Nat. Lab.
Louisiana State U.
M.I.T.
Michigan State U.
Middlebury College
McDonald Observatory
NASA Ames
NASA Goddard
New Mexico State U.
Ohio State U.
Pennsylvania State U.
Prism Comp. Sciences Inc.
Rice U.
Rutgers U.
Space Telescope Science Inst.
Smith College
State U. of New York
Towson U.
U. of Arizona
U. of California, Berkeley
U. of California, Santa Cruz
U. of California, San Diego
U. of Chicago
U. of Colorado
U. of Florida
U. of Illinois
U. of Kansas
U. of Maryland
U. of Massachusetts, Amherst
U. of Michigan
U. of Minnesota
U. Nac. Autónoma México
U. of North Carolina
U. of Texas, Austin
U. of Virginia
U. of Washington
U. of Wisconsin, Madison
U. of Wisconsin, Oshkosh
US Naval Observatory
Yale U.

Latin American Institutions (11)
Fac. Ciencias, Uruguay
Obs. Nacional, Brazil
Pontificia U. Católica de Chile
U. de Chile
U. de Concepción, Chile
U. de La Serena, Chile
U. de Sao Paulo, Brazil
U.F.M.G., Brazil
U.F.RG.S., Brazil
U. Nac. Córdoba, Argentina
U. Nac. La Plata, Argentina

For the 12 months ending 31 July 1999, 224 observing programs were carried out at Kitt Peak facilities. These involved 653 individual scientists from 232 institutions (140 US and 92 foreign). The top five institutions, ranked by number of PI's awarded proposals, were the following:

        Institution                                  PI's
        Space Science Telescope Institute            32
        Harvard-Smithsonian Center for Astrophysics  21
        University of California, Berkeley           20
        University of Colorado                       18
        California Institute of Technology           18

For the 12 months ending September 30, 1999, a total of 174 observing programs, involving 95 individual scientific visitors in addition to 21 scientific and 9 technical staff, were carried out at NSO facilities. A total of 84 unique scientific projects were undertaken by astronomers from 43 institutions (30 US and 13 foreign). During the same period, staff and users of NSO facilities published 193 papers. Visiting astronomers were assigned 36% of the scheduled telescope time and the remaining 64% was assigned to staff.