We present a mid-infrared (MIR) analysis of 35 quasars with spectroscopic redshifts selected from the Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE). We discuss their optical and MIR colors and show that these quasars occupy well-defined regions in MIR color-color space. We examine the issue of type 1 active galactic nuclei candidate

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A concept is described for the high-accuracy absolute calibration of the instrumental polarization introduced by the primary mirror of a large-aperture telescope. This procedure requires a small aperture with polarization-calibration optics (e.g., mounted on the dome) followed by a lens that opens the beam to illuminate the entire surface of the

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We report R band imaging polarimetry of SN 2004bv in NGC 6907 on June 19.299 (UT middle of observation), i.e., two weeks after maximum. We have obtained [ 0.11 ± 0.02] % at position angle 118.7 ° for the observed polarization. The average foreground polarization from field objects was estimated to be [ 0.12 ± 0.02] % at PA 163.4 °, consistent with