CoreSite Realty Corporation, a data center REIT with over 600 customers and a portfolio of 10 operating facilities, filed on Thursday with the SEC to raise up to $230 million in an initial public offering. The Denver, CO-based company, which purchased its first data center in 2000 through funds affilliated with The Carlyle Group, booked $29 million in sales last year. The REIT plans to list on the NYSE under the symbol COR. Citi, BofA Merrill Lynch and RBC Capital Markets are the lead underwriters on the deal, for which pricing terms and timing were not disclosed.