We are performing a uniform and unbiased imaging survey of the Large Magellanic Cloud (LMC; $7 ; 7) using the IRAC (3.6, 4.5, 5.8, and 8 m) and MIPS (24, 70, and 160 m) instruments on board the Spitzer Space Telescope in the Surveying the Agents of a Galaxy's Evolution (SAGE) survey, these agents being the interstellar medium (ISM) and stars in the LMC. This paper provides an overview of the SAGE Legacy project, including observing strategy, data processing, and initial results. Three key science goals determined the coverage and depth of the survey. The detection of diffuse ISM with column densities >1:2 ; 10 21 H cm À2 permits detailed studies of dust processes in the ISM. SAGE's point-source sensitivity enables a complete census of newly formed stars with masses >3 M that will determine the current star formation rate in the LMC. SAGE's detection of evolved stars with mass-loss rates >1 ; 10 À8 M yr À1 will quantify the rate at which evolved stars inject mass into the ISM of the LMC. The observing strategy includes two epochs in 2005, separated by 3 months, that both mitigate instrumental artifacts and constrain source variability. The SAGE data are nonproprietary. The data processing includes IRAC and MIPS pipelines and a database for mining the point-source catalogs, which will be released to the community in support of Spitzer proposal cycles 4 and 5. We present initial results on the epoch 1 data for a region near N79 and N83. The MIPS 70 and 160 m images of the diffuse dust emission of the N79/N83 region reveal a similar distribution to the gas emissions, especially the H i 21 cm emission. The measured point-source sensitivity for the epoch 1 data is consistent with expectations for the survey. The point-source counts are highest for the IRAC 3.6 m band and decrease dramatically toward longer wavelengths, A

We have determined the ratios of total to selective extinction in the near-infrared bands (J; H; K s ) toward the Galactic center from the observations of the region jlj P 2N0 and 0N5 PjbjP1N0 with the IRSF telescope and the SIRIUS camera. Using the positions of red clump stars in color-magnitude diagrams as a tracer of the extinction and reddening, we determine the average of the ratios of total to selective extinction to be A K s /E HÀK s ¼ 1:44 AE 0:01, A K s /E J ÀK s ¼ 0:494 AE 0:006, and A H /E J ÀH ¼ 1:42 AE 0:02, which are significantly smaller than those obtained in previous studies. From these ratios, we estimate that A J :A H : A K s ¼ 1:0:573 AE 0:009:0:331 AE 0:004 and E J ÀH /E HÀK s ¼ 1:72 AE 0:04, and we find that the power law A k / k À1:99AE0:02 is a good approximation over these wavelengths. Moreover, we find a small variation in A K s /E HÀK s across our survey. This suggests that the infrared extinction law changes from one line of sight to another, and the so-called universality does not necessarily hold in the infrared wavelengths.

Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency of solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing analogs of all the solar system planets except Mercury. We report the detection of a multiple-planet system with microlensing. We identify two planets with masses of approximately 0.71 and approximately 0.27 times the mass of Jupiter and orbital separations of approximately 2.3 and approximately 4.6 astronomical units orbiting a primary star of mass approximately 0.50 solar mass at a distance of approximately 1.5 kiloparsecs. This system resembles a scaled version of our solar system in that the mass ratio, separation ratio, and equilibrium temperatures of the planets are similar to those of Jupiter and Saturn. These planets could not have been detected with other techniques; their discovery from only six confirmed microlensing planet detections suggests that solar system analogs may be common.