The Boston Modern Orchestra Project (BMOP), the nation’s premier orchestra dedicated exclusively to commissioning, performing, and recording new orchestral music, begins its 23rd season with Time Release: a one-night-only concert of orchestral music headlined by the American premiere of Steven Mackey’s Time Release. Led by Artistic Director and Conductor Gil Rose, BMOP also celebrates the Boston premieres of Tonic by Steven Mackey, Concerto No. 2 for Harp and Orchestra by Hannah Lash, and Vision Machine by Harold Meltzer.