Assigned ID: 422 ----- Submission 1 (Fri Jan 21 21:50:52 GMT 2005) ----- Observations of nearby galaxies with the Chandra X-ray observatory reveal a multitude of X-ray point sources, largely X-ray binaries and SNR. The X-ray data can provide crude classifications for these sources, but the only way to unambiguously classify the source is by observing an optical counterpart. The Hubble Heritage observations of M51, to be taken before the beginning of Cycle 14, provide the perfect optical dataset for comparison with existing X-ray data, combining large field of view, high angular resolution, and long exposure times. The resulting information on optical counterparts and environments will allow us to test two important X-ray diagnostics: first, that X-ray color can be used as a crude method of source classification, and second that the environment of X-ray sources within a host galaxy can help determine the formation history of the X-ray population.

GALAXIES 12 30000 false 0.0 false false false false false SUPPORTED