Maryland Gov. Martin O’Malley (D) and his wife are planning to welcome close to 200 supporters of same-sex marriage to the governor’s mansion Friday night to celebrate the arrival of gay nuptials in the Free State. Invitations to the event bill it as a “holiday celebration.” But the cover features a photo of the black-and-white “Dignity” button that O’Malley wore as he championed the legislation this year, and aides confirmed the purpose is to thank supporters. That includes a few celebrities, such as Baltimore Ravens linebacker Brendon Ayanbadejo. O’Malley signed a same-sex marriage bill into law in March, but it was petitioned to referendum by opponents. Last month, Maryland voters supported a ballot measure upholding the new law, 52 percent to 48 percent. Prior to Election Day, no other state had authorized gay marriage by a popular vote. “This is an opportunity to celebrate its passage and thank the many, many people and organizations who helped ensure the passage of the bill and the referendum,” said O’Malley spokeswoman Raquel Guillory. She said the state will cover the cost of the event.