The trombone played by William Riker, a keen amateur jazz musician, in holodeck clubs and at shipboard gatherings throughout The Next Generation.
Riker's love of jazz is established early in The Next Generation. In 11001001 he tries out an upgraded holodeck by creating a New Orleans jazz club, where he sits in with the band on trombone and meets the holographic Minuet.
The instrument returns regularly. He plays at the memorial gathering for Geordi La Forge and Ro Laren in The Next Phase, and in Second Chances the appearance of his duplicate, Thomas Riker, is tied to a solo from the tune Night Bird that he has never managed to get right. Future Imperfect opens with him playing for the crew at his own birthday party.
Later series keep the joke alive, with references to his playing in Lower Decks and Star Trek: Picard.