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Session 10 - Studies of Black Holes.
Display session, Monday, June 09
South Main Hall,
We have secured a 7-orbit spectrum of the nuclear region of M31, taken with the HST/FOC f/48 long-slit spectrograph. The pixel is 56 mas along the slit and 1.8 Å\ in wavelength, while the image of the spectrograph slit is 2.3 pixels wide. We believe that the slit was laid across the two nuclei to better than 50 mas. In spite of low S/N and lack of previous calibration of the spectrograph, we have measured a rotation curve of the central region. Our measurements appear to have achieved full spatial resolution, and show a linear portion that peaks 0.4 arcsec (\sim 7 pixels) on either side of the center of rotation, which is close to (but not coincident with) the P2 peak. The amplitude is more than 200 km/s on either side of the mean velocity. The curve shows no measurable perturbation in the region of the optically brighter peak P1. Our measurements have been greatly impeded by a patterned dark current and cosmetic defects in the detector; we are still working to confirm these preliminary results and to improve their quality.
