Improved Evidence for a Black Hole in M32 fromHST/FOS Spectra. I. Observations

We have obtained spectra through small apertures centered on the nuclear region and major axis of M32 with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST ). A detailed analysis and reduction of the data is presented, including (1) new calibrations and modeling of the FOS aperture sizes, point-spread function, and line-spread functions ; (2) determination of the aperture positioning for each observation from the observed count rate ; and (3) accurate wavelength calibration, template matching, and kinematical analysis of the spectra. This yields measurements of the stellar rotation velocities and velocity dispersions near the center of M32 with spatial resolution that is 5 times higher than the best available ground-based data. The inferred velocities provide the highest angular-resolution stellar-kinematical data obtained to date for any stellar system.