watchOS 5.1 (build 16R5589c) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-10-22T17:19:32Z. The update package is 63.33 MB. This is a delta (partial) update that requires 5.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: ad7677f7db1e1fba880b28428cb7c90d65d711be.zip.