The screen resolutions for Apple’s various iOS devices are:

* new iPads and iPad Minis: 2048 x 1536
* old iPads and iPad Minis: 1024 x 768
* iPhone 5s and new iPod Touches: 1136 x 640
* iPhone 4s and old iPod Touches: 960 x 640

If I want a minimum size for their to be a sidebar, 1000 pixels looks like a good minimum.