Assigned ID: 219 ----- Attempting Submission 1 (Thu Feb 24 23:09:16 GMT 2011) ----- HST Phase I Proposal 219 (omega_cen.apt) successfully submitted. ----- Attempting Submission 2 (Fri Feb 25 19:41:54 GMT 2011) ----- HST Phase I Proposal 219 (omega_cen.apt) successfully submitted. ----- Attempting Submission 3 (Sat Feb 26 00:23:37 GMT 2011) ----- We propopse to apply the technique of color-magnitude diagram (CMD) fitting to archival HST/ACS and WFC3 imaging of Omega Centauri in order to measure its star formation history (SFH). As the remnant of a captured satellite galaxy, the SFH of Omega Cen will provide key insights into its formation and evolution before and after its incorporation into the Milky Way. The derivation of SFHs from CMD analysis has been well-established in the Local Group and nearby galaxies, but has never been applied within our Galaxy. Archival HST imaging of Omega Cen provides for exquisitely deep CMDs with broad wavelength coverage (near-UV through I-band), which allows for clear separation of age-sensitive CMD features, and can be leveraged to highly constrain its star formation rate as a function of time. In addition, the CMD fitting technique also allows us to test for consistency in recovered SFHs using different stellar models, and quantitatively tie the UV characteristics of ancient stellar populations to a SFH.

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