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Hubble Space Telescope
Achieving 10-6 Contrast Visible Light Coronagraphy with BAR5

We report on the recent results of the CAL/STIS program 14426, “Pushing the Limits of BAR5”, which sought to investigate the limiting factors to high contrast imaging with the new BAR5 position in the 50CORON aperture. The program employed azimuthal differential imaging and sub-pixel dithering behind the BAR5 mask in order to obtain the highest possible contrasts possible. With a combination of this observing strategy and post-processing of the data using Karhunen-Loeve Image Projection (KLIP, Soummer et al., 2013), we have obtained 10-6 contrast at an inner working angle of 0.6” and 10-5 contrast at an inner working angle of 0.25”. These results demonstrate that high contrast imaging with STIS/BAR5 can achieve contrasts within a factor of 2 of the photon limit due to the wings of STIS’s point source function. More information on the details of these results are located at http://www.stsci.edu/hst/stis/strategies/pushing/coronagraphy_bar5