Scramble code 1477, was a Galactic Republic encryption code used for secret transmissions.
Shortly before the Mission to Skytop Station in 22 BBY, the Jedi General Anakin Skywalker detected the secret Separatist listening post Skytop Station in the orbit of Ruusan 2. He instructed the Astromech droid R3-S6 to use scramble code 1477 in order to contact the Jedi Obi-Wan Kenobi without the station picking them up. Skywalker reports to Kenobi, who eventually tells him to sneak onboard the Separatist outpost. R3-S6, who turned out to be a separatist agent, would later contact General Grievous and tell him about the Jedi intrusion.