Story highlights Steve Tran claims his half of $648 million Mega Millions jackpot

Tran tells lottery officials he didn't realize he won until Monday -- 13 days after drawing

Jackpot was second-largest in U.S. lottery history

Georgia woman claimed other half last month

It apparently took him a few days to realize it, but California resident Steve Tran is one of the two winners of the second-largest jackpot in U.S. history, lottery officials said Friday.

Tran, a delivery driver from Northern California, came forward Thursday to claim his half of last month's $648 million Mega Millions jackpot, after spending nearly two weeks oblivious to his win, the California Lottery said.

Tran still has 60 days to decide how to take his prize, the lottery said. He can choose either to receive his half in annuity payments over 30 years, or take his share of the lump-sum cash option, valued at $173.8 million before taxes, it said.

Georgia resident Ira Curry , 56, was the other winner. Curry, who claimed her prize a day after the December 17 drawing, took the $173.8 million lump-sum option, which will net her about $120 million after federal and Georgia taxes.

Tran, who declined to speak to reporters but told his story to lottery officials, bought his winning ticket at a San Jose gift shop and put it in a pile of other lottery tickets that he bought in other towns while making runs as a delivery driver, the lottery said.

It wasn't until Monday, after taking a vacation with his family, that he remembered to check his ticket, he said.

"I woke up in the middle of the night. I remembered, 'I think I went to San Jose,'" he said, according to the lottery.

The winning numbers were 8, 14, 17, 20 and 39, with a Mega ball of 7.