This database table contains the Spitzer Space Telescope (SST) log of executed and scheduled observations, and is updated on a weekly basis. Spitzer is the fourth and final element in NASA's family of Great Observatories and represents an important scientific and technical bridge to NASA's Astronomical Search for Origins program. The SST Observatory carries an 85-cm cryogenic telescope and 3 cryogenically cooled science instruments capable of performing imaging and spectroscopy in the 3.6 to 160 micron (µm) range. Spitzer was launched on a Delta 7920H from Cape Canaveral into an Earth-trailing heliocentric orbit in August 2003. While the Spitzer cryogenic lifetime requirements are 2.5 years, current estimates indicate that achieving a goal of a 5-year cryogenic mission is possible. For more overview information, refer to the Spitzer Science Center (SSC) Overview at <a href="http://ssc.spitzer.caltech.edu/spitzermission/">http://ssc.spitzer.caltech.edu/spitzermission/</a>;. The purpose of this HEASARC table is to help users, particularly those in the high-energy astronomy community, learn about which targets Spitzer has observed or will shortly observe. This table does not at this time have links from table entries to Spitzer data products. Once a particular Spitzer dataset of interest is identified, the SSC Archives/Analysis web page at <a href="http://ssc.spitzer.caltech.edu/archanaly/">http://ssc.spitzer.caltech.edu/archanaly/</a>; should be used to access the dataset. The information in this table has been derived from the following files obtained from the SSC website: <p> The schedule of Spitzer science observations as executed: <pre> <a href="http://irsa.ipac.caltech.edu/data/SPITZER/docs/files/spitzer/spitzer_obslog.txt">http://irsa.ipac.caltech.edu/data/SPITZER/docs/files/spitzer/spitzer_obslog.txt</a>; </pre> The list of all approved Spitzer science programs: <pre> <a href="http://irsa.ipac.caltech.edu/data/SPITZER/docs/files/spitzer/spitzer_programs.txt">http://irsa.ipac.caltech.edu/data/SPITZER/docs/files/spitzer/spitzer_programs.txt</a>; </pre> Notice that this table contains primarily observations (identified by their AOR key value) from the first URL above. A given observation should appear only once in this HEASARC table. The HEASARC checks these URLs for modifications periodically and updates the table whenever changes are detected. This is a service provided by NASA HEASARC .