iPadOS 9.1 (build 13B137) is an official Apple over-the-air update for the iPad 2 (Mid 2012), released on 2015-10-12T16:56:47Z. The update package is 965.6 MB. This is a delta (partial) update that requires 9.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 0976ad6af444b422b72d391aad888fe830998797.zip.