Welcome to On the Radar, where we preview upcoming arts events to mark your calendars for. The 600 block of Central Avenue in downtown St. Petersburg was recently dubbed the city’s new arts district. Between redevelopment and revivals, a collection of more than 30 new businesses – including art and design studios, music outlets, film studios, galleries, boutiques, and a public journalism organization – have opened up … and business is boomin’. To celebrate the creative “neighborhood” and the grand opening of the newly renovated Crislip Arcade, there’s going to be a banging 600 Block Party this weekend.