* Offering to pay off purchase of Ante Creek assets

* Syndicate of underwriters led by RBC Capital Markets

TORONTO, Jan 5 - ARC Energy Trust (AET_u.TO) said on Tuesday it had raised C$252 million ($242 million) in a bought deal equity offering to help pay off the acquisition of natural gas assets in December.

The conventional oil and gas royalty trust said it would use part of the proceeds to repay bank debt of C$180 million incurred to buy assets in Ante Creek and other areas of northern Alberta last month.

ARC said the previously announced offering sold 13 million trust units at C$19.40 each on a bought deal basis. Originally, the trust said it would sell 10.3 million units for proceeds of C$200 million.

The syndicate of underwriters was led by RBC Capital Markets (RY.TO) and included the capital market arms of all of Canada's top banks: CIBC World Markets Inc (CM.TO), BMO Capital Markets (BMO.TO), Scotia Capital Inc (BNS.TO), TD Securities Inc (TD.TO) and National Bank Financial Inc (NA.TO).

Underwriters also included FirstEnergy Capital Corp, Canaccord Financial Ltd, Peters & Co Ltd, Macquarie Capital Markets Canada Ltd, Raymond James Ltd, Thomas Weisel Partners Canada Inc, and UBS Securities Canada Inc.

ARC agreed in December to buy a general partnership producing natural gas in the Ante Creek region, boosting its output and adding reserves and exploration lands near its own holdings.

The acquisition adds 2,000 barrels of oil equivalent a day of new production -- rising to 2,500 boed next year -- and adding to the 5,000 boed that Arc already produces in the Ante Creek area.

It also adds 7 million barrels of proved reserves and boosts the trust's portfolio of exploration lands by 20 percent.

ARC units fell 0.72 percent, or 15 Canadian cents, to C$20.65 on Tuesday morning on the Toronto Stock Exchange.

($1=$1.04 Canadian) (Reporting by Pav Jordan; editing by Rob Wilson)