Pretty sure that was in one of the story chapters, and I would expect it to be the local physical midnight for wherever he's standing, at least in a reasonably normal environment. How that interacts with being in space or somewhere with a very different day length (the poles near solstice, other planets with longer or shorter days, etc.) is a question only Bob and/or the V&V GM can answer.
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‎noli esse culus
‎noli esse culus