The source code can be found here: https://github.com/aragaer/jtt_android
Note: Unlike most other applications of the kind, this one does not use network to get sunrise and sunset time, everything is calculated locally.
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Market link: com.aragaer.jtt
Web site: http://aragaer.github.com/jtt_android/
Market downloads: 1,000-5,000
Market rating: 4.5 / 5.0