Inland Rule Annex IV 87.1 Distress Signals section (p)- A high intensity white light flashing at regular intervals from 50 to 70 times per minute.
Also Rule 37 Inland Rules Distress Signal- A high intensity white light flashing at regular intervals from 50 to 70 times per minute.
International Rules don't care but the strobe won't meet international requirement for anchor light on vessels 7 meters or longer.