Mayor Marty Walsh has made official something fans of the band already knew: Thursday is Mighty Mighty Bosstones Day in Boston. In honor of the plaid-clad rockers’ annual Hometown Throwdown, a series of shows that kicks off tonight at the House of Blues, Hizzoner proclaimed Thursday Mighty Mighty Bosstones Day in the city. Band leader Dicky Barrett and his ska ensemble join Guster, Kathleen Hanna, Patti Smith, Peter Wolf, and Judd Apatow (among others) in getting their very own day courtesy of Mayor Walsh. (The mayor will personally present the proclamation at the band’s show Friday.) Over 30 years, the Bosstones have released nine albums, including the double-platinum “Let’s Face It,” which is celebrating its 20th anniversary. This year’s Throwdown runs through Saturday, but if you don’t have a ticket yet, you may have a hard time finding one. That’s the impression we get, at least.