One of Washington’s best informed and most articulate jazz authorities, the affable Rusty Hassan appears tonight to offer a whirlwind musical history called “That’s Jazz.” His presentation, illustrated by audio and video excerpts, will focus on the contributions of numerous jazz giants, among them Jelly Roll Morton, Louis Armstrong, Duke Ellington, Billie Holiday, Charlie Parker, and Dizzy Gillespie. Prepare to be entertained and enlightened by this linchpin of the local jazz community, whose invaluable “Jazz Sunday” program on WDCU-FM is endangered by the pending sell-off of UDC’s radio station. At 7:30 p.m. at the Corcoran Gallery of Art’s Hammer Auditorium, 17th & New York Ave. NW. $12. (202) 639-1770. (Joel E. Siegel)