AAS 205th Meeting, 9-13 January 2005
Session 5 Visible/UV/IR Space Missions and Technology
Poster, Monday, January 10, 2005, 9:20am-6:30pm, Exhibit Hall

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[5.04] NICMOS Coronagraphic Polarimetry: A New Observing Mode for HST

D.C. Hines (Space Science Institute), G. Schneider (University of Arizona)

We present results from our recent program to evaluate, calibrate, and enable for commissioning, high-contrast near-IR imaging polarimetry via coronagraphy with NICMOS on the Hubble Space Telescope (HST). We find that the HST/NICMOS Camera 2 polarizing filters can be used efficiently and effectively in combination with the coronagraph, reducing instrumental scatter and diffracted energy from coronagraphically occulted bright targets. Imaging polarimetry is now enabled in spatially extended diffuse regions of low surface brightness (in contrast to their central sources), such as circumstellar disks around largely unembeded stars, and active galactic nuclei. This mode, which provides diffraction limited polarimetric imagery at 2.0 microns (with 10% FWHM pass band), has now been made available for use in HST Cycle 14 through STScI's call for proposals.

Our commissioning program included science demonstration observations of the T-Tauri star TW Hya, known to posses a nearly face-on circumstellar disk (previously imaged with NICMOS camera 2, non-polarimetrically at 1.1 and 1.6 microns). We find that the disk is polarized with percentage polarization reaching 10-30% per (0.2 arcsec) resolution element.

We also discuss the use of coronagraphic polarimetry for observing a variety of targets with HST, and the importance of incorporating polarizing optics into future space-based coronagraphic facilities such as TPF-C.

Support for this work was provided by NASA through grant number GO-9768 from the Space Telescope Science Institute, which is operated by Association of Universities for Research in Astronomy Incorporated, under NASA contract NAS5-26555.

The author(s) of this abstract have provided an email address for comments about the abstract: dean.hines@colorado.edu

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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.