SLR-Urgent is a mail exploder to be used by mission control centers or prediction centers to inform station operators about any urgent matters concerning the tracking of their respective satellites (e.g., modification of tracking priorities, information about satellites with unusually large time biases, attitude problems of satellites, upcoming maneuvers, tracking information after the launch of new satellites).URGENT was proposed by Werner Gurtner and Carey Noll to the ILRS via SLRMail 645 on 16 August 2000.