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D. S. Theil, D. I. Klebe, R. E. Stencel (Univ. of Denver)
Building on our success with TNTCAM (Klebe et al., 1996, ASP Conf. Series, v97, p79) we present progress on a new mid-IR (5-25\mum) imaging polarimeter, TNTCAM (Ten and Twenty \mum Camera) MARK II. With a Boeing 256x256 Si:As BIB array, the camera will surpass any instrument currently in use at these wavelengths as an imager and polarimeter. All optics are chilled to liquid helium temperatures, excluding the entrance window; there are currently no mid-IR array polarimeters with all cold optics. In polarimetry mode TNTCAM II will be sensitive to linear polarizations as small as 0.4% (at 6.0 magnitudes arcsec-2 on a 2.4m telescope in four hours). Our current schedule achieves first light during 1999. Community access is planned as part of the funding agreement under a NSF Major Research Infrastructure grant.
To measure polarimetry the camera images one polarization state at a time. Modulating the polarization faster than atmospheric and system noise fluctuations requires rotating waveplates rapidly at LHe temperatures. We present details of our mechanical design showing how this is accomplished. We also present a rotating window assembly allowing on-the-fly f-ratio adjustment and observation across the entire 5-25\mum band.
This camera will contribute to the understanding of YSOs and evolved stars, obtaining high resolution mid-IR observations of dusty environments surrounding these objects. Mosaics of extended objects can be made with 2\prime\times 2\prime sub-fields. In polarimetry mode, assuming adequate grain alignment timescales, magnetic fields in YSOs can be probed by dust emission from hot cores. The camera will constrain grain alignment scenarios in young stellar environments and around evolved stars, and will be useful for exploring the magnetic fields of external galaxies.
We acknowledge support under NSF grant AST-9724506 to the University of Denver.
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The author(s) of this abstract have provided an email address for comments about the abstract: theil@casa.colorado.edu