The Riverside Philharmonic will celebrate the Jewish new year and High Holy Days with the world premiere of “Symphony No. 1: Judaica (Days of Awe)” by Los Angeles-based composer Steve Rothstein, a piece commissioned by the Judaic Sacred Music Foundation. The concert is at 4 p.m. Sept. 18 at the Fox Performing Arts Center, 3801 Mission Inn Ave., Riverside. Rothstein and Tomasz Golka, the orchestra’s music director, will give a preconcert talk at 3:30 p.m., and doors open at 2:30 p.m. The program, celebrating Jewish-American composers, will also feature the Piano Concerto in F by GeorgeGershwin, featuring guest artist Neal...