The term Sidereal Era was used in relation to a calendar that, as of 1 ABY on the planet Fusai, was used for biographical details such as birthdates in the files of the BRT supercomputer Mistress Mnemos.
- Birth of Chewbacca: Sidereal Era AF-5076, or 200 BBY in the Galactic Standard Calendar.
- Birth of Gyla Petro: Sidereal Era AS-5667.
- Birth of Luke Skywalker: Sidereal Era AS-5670, or 19 BBY (16:5:26) in the Galactic Standard Calendar.
The term "sidereal period" in astronomy is defined as the time that it takes an object to make one full orbit around its sun, relative to the surrounding stars—in other words, a planet's local "year."
A similar term used in ads on the HoloNet News website is "Sentient of the Sidereal," which essentially means "Person of the Year." There has never been a connection made in canon between the two items.