New York ? Soon, the Met will be on the air almost as much as the Mets.

Sirius Satellite Radio and the Metropolitan Opera announced Wednesday that they would launch a new channel to broadcast four performances a week during the company’s 32-week season, part of the company’s vast media expansion under new general manager Peter Gelb.

Metropolitan Opera Radio will debut with Monday’s opening-night gala of a new production of Puccini’s “Madama Butterfly.” When not broadcasting live performances, the channel will air operas from the Met’s archive of 1,500 radio broadcasts that date to 1931.

The announcement follows deals to broadcast six live performances this season in high definition to movie theaters in North America and Europe, which will be televised later on PBS, and to stream live performances on the Met’s Web site, which launched its redesign Tuesday.

“The Met right now is the talk of the opera world, I would say, because of all these new initiatives,” Gelb said. “All of these initiatives have one common purpose, which is to improve the Met’s position by educating audiences and increasing the box office.”

Seventy-seven percent of the Met’s available tickets were sold last season, down from 93 percent in 1999-2000.

Met spokeswoman Sommer Hixson said the company had not yet determined how much overlap there would be between the radio channel and the Internet streaming, which will include at most a weekly performance. The streaming is designed to promote the subscription service.

Sirius, which has about 125 channels, has a subscription price of $12.95 per month, with discounts available for long-term deals. It was available to 4.7 million subscribers at the end of June and expects to be in 6.3 million by the end of the year, spokesman Patrick Reilly said.

XM Satellite Radio, its competitor, has 170 channels and is currently available to 7 million customers.

“There’s nothing like the Met, and more importantly, there’s nothing like the Met archives of the great operas that have taken place over the years,” said Scott Greenstein, Sirius’ president of entertainment and sports. “The idea that we could have our channel and get the best of the current stuff right now as well as the archives, it’s something very unique we could bring to our subscribers.”

The Met’s media expansion was made possible by new deals with its unions that were announced Sept. 6.

Sirius will have 10 historic broadcasts per week, Hixson said. The Met also is making about 500 of its 1,500 archived broadcasts available through RealNetworks’ Rhapsody online service.

The Met Radio Channel will replace Classical Voices on Sirius. Greenstein would not say how many new subscribers Sirius hopes to get because of the Met channel.

Instead of the original commentary by Milton Cross and Peter Allen and original intermission features, the historic broadcasts will be repackaged with new lead-ins and intermissions. The channel’s announcer will be Margaret Juntwait, who replaced Allen in 2004 as host of the Met’s Saturday afternoon radio broadcasts, which run from December until spring and will continue.