Casperia Prime was a ringed planet in the Alpha or Beta Quadrants, and a popular vacation destination in the 24th century.
Along with Risa, Wrigley's Pleasure Planet and Phloston Paradise, Casperia Prime has been one of the Federation's most popular holiday destinations for more than two centuries. (SCE eBook: The Future Begins)
Jennifer Almieri and her husband honeymooned on Casperia Prime in 2327. (CoE eBook: Ghost)
Shortly after Thirishar ch'Thane graduated from Starfleet Academy, he and Shathrissia zh'Cheen vacationed on Casperia Prime. They spent days climbing, and Thriss later said it had been her best vacation ever. (DS9 - Mission: Gamma novel: This Gray Spirit)
In 2374, Jadzia Dax planned her honeymoon with Worf on Casperia Prime. Jadzia had consulted a Starfleet Bureau of Information database on the planet. (DS9 episode: "Change of Heart")
Later that year, a medical conference was held on Casperia Prime, which Julian Bashir had planned to attend. (DS9 episode: "Inquisition")
A number of papers had been presented at that conference, which Bashir dutifully read through weeks afterward. (DS9 novel: Hollow Men)