NIST distributes frequency and time signals by radio, referenced to UTC(NIST), to users in all 50 states. Radio Stations WWV, in Ft. Collins, Colorado, and WWVH located on the island of Kauai in Hawaii, operate a combined total of ten transmitters in the HF (high frequency) spectrum. They broadcast standard carrier frequencies, audio announcements of time, and related information. They also serve as space weather beacons that assist scientists involved in ionospheric research. Radio Station WWVB, also located in Ft. Collins, operates in the LF (low frequency) portion of the spectrum at 60 kHz. Its signals synchronize tens of millions of radio-controlled clocks and also serve as a frequency reference.