NOTES: CXC, Chandra X-ray Center; CXO, Chandra X-ray Observatory; EPO, education and public outreach; FTE, full-time equivalent; HEASARC, High Energy Astrophysics Science Archive Research Center; HST, Hubble Space Telescope; IPAC, Infrared Processing and Analysis Center; RXTE, Rossi X-ray Timing Explorer; SSC, Spitzer Science Center; SST, Spitzer Space Telescope; STScI, Space Telescope Science Institute; XMM–Newton, X-ray Multimirror Mission–Newton.

^aSTScI has a contract to operate the Multimission Archive at Space Telescope Science Institute (MAST), $3 million annually, which is not included in this table or in the budget total shown. The MAST archive contains 10 Tb of data from IUE, GALEX, FUSE, and other missions.

^bXMM–Newton is a European mission and flight operations are the responsibility of ESA.

^cThe NASA mission budget includes science and mission operations costs at the science centers and grants to the community plus: science and mission operations costs at the related NASA centers; industrial contractors; and PI sustaining engineering. It does not include new PI-led instrument development, servicing mission costs, or foreign contributions.

^dThe total budget for the science centers themselves; that is, only those items shown in italics in footnote c.

^eThe amount shown as grants includes funds granted for theory and/or data analysis to PIs, legacy teams, guest observers, and fellows, as well as the support of the fellowship positions.

^fNumber of total FTE for HST at STScI includes 15 FTE funded by ESA. It does not include indirect staff even though their cost is contained in the total budget. This is done to make a fair comparison with the Chandra and Spitzer centers. The cost for staff with this function (human resources, accounting, purchasing, etc.) is covered by an overhead applied to salaries at the Chandra and Spitzer centers, with the overhead cost contained in their total budget. As a result, these overhead functions do not appear in their staff numbers. It does not include flight operations staff even thought their cost is contained in the total budget. Again, this is done to make a fair comparison with the Chandra and Spitzer centers. At Spitzer and Chandra, flight operations are contracted to JPL and Marshall Space Flight Center, respectively.

^gIncluding staff time for research.

^hThe number of users served shown for Spitzer is for 2005 and was derived by counting all PIs, co-investigators, etc., and dividing by three on the assumption that each individual is counted three times on average.

ⁱThe number of grants listed represents the number of PIs; separate grants made to co-PIs have not been included. The total number of astronomers sharing the support for observing programs is obviously larger than the number of grants.

^jThe table gives the number of observation data sets requested per year. As each download request may contain several observations, this number may be larger, by definition, than those for the other centers.