Auras, invisibility, foci, and kittens Options

[katiegreen]

The question of how far an aura extends brings up an interesting point. If I cast improved invisibility on myself, what exactly does it make invisible? I'd say that it's pretty standard to make me and my clothes, armor, etc. invisable. The idea I'd heard explaining this is because it is within your aura, though there isn't any cannon I can find backing this up. Well, what about a hiking backpack? That's pretty big. Or an assault rifle? Or a deck? Is that still in your aura? How about in your invisibility? What if I put my invisibility spell into a sustaining focus? Then the focus is magically active, with it's own astral presence . . . most people would argue that it isn't in my aura any more, but would it be invisible? What if I'm holding a kitten? Is the kitten invisible, or do I have to cast it on the kitten as well? What if the kitten is under a jacket? Or in the hiking backpack? Hiding behind something that is invisible doesn't make you invisible, so would this result in a kitten appearing to float through mid-air? If a guard sees said kitten, would he get a reduced target number/a second chance to see the runner holding the cat?

EDIT: If you pick up the kitten after you cast the spell, would that be different than if you're holding the kitten at the time of casting?