The Mets fired manager Art Howe yesterday, but left him in the dugout for the final 2 1/2 weeks of a season gone bad after the All-Star break.

Hours later, the Mets were shutout by the Atlanta Braves for their 21st loss in 25 games.

Atlanta cut its magic number to 10 for clinching its 13th straight division title. The Braves won despite getting only four hits, including Marcus Giles’s two doubles and a single.

John Thomson (12-8) gave up five hits in seven innings, improving to 3-0 in four starts against the Mets this season.

Al Leiter (9-7) lost despite allowing just three hits in seven innings and striking out 11.

General manager Jim Duquette said he wanted to announce Howe’s firing after the year, but was forced to act this week after news broke of his plan. He said he asked Howe to stay for the final 17 games, and the manager agreed.

“The fact is, I’m not fired now. I’m leaving after the season,” Howe said during an awkward day at Shea Stadium. “I’m not a quitter.”

Howe’s contract runs through the 2006 season and he’s still owed $4.7 million. But with the Mets at 63-83 – following a 66-95 finish last year in his first season – management decided it was time for a change.

“I saw strength and courage and conviction when I met Art Howe and I said, ‘Let’s go,'” owner Fred Wilpon said on a conference call. “I take full responsibility that the results weren’t there.”

Wilpon said Duquette would choose the next manager, and there are sure to be plenty of big names in the mix.

Former Mets stars Gary Carter, Lenny Dykstra, and Wally Backman have been mentioned, as have current major league managers Lou Piniella and Buck Showalter, along with former Arizona manager Bob Brenly. Even former manager Bobby Valentine, who guided the Mets to the 2000 World Series, could get a look.

The Mets began the year with a payroll over $100 million, highest in the NL. But injuries took their toll, and they rapidly fell out of contention after the midseason break.

“I don’t want to get into an evaluation of Art,” Duquette said. “It wasn’t working.”

Howe told the team about the move before they took batting practice, and said the clubhouse was “very quiet.”

“It’s unfortunate,” Cliff Floyd said. “We all know that when things don’t go well on the field, the first person to take the blame is the manager.”

Asked what Howe said at the start of the meeting, Floyd said he missed that part of the talk.

News broke earlier this week that the Mets would fire Howe, who guided Oakland to playoff appearances from 2000-02, after this season. He met with Duquette and Wilpon on Tuesday, and Duquette told Howe the plans but also asked him to serve out the season.

The Mets were only one game out of the NL East lead when they won their first game after the All-Star break. But after July 15, they went on a 16-38 skid that dropped them far out of contention. They went into last night’s game with Atlanta trailing the division leading Braves by 22 games.

Howe, 57, said he’d think later about whether he’d want to manage another ball club in the future.

“After this season, I’m going to have to thaw out, to say the least,” he said.