They can't. I don't think they are high in the sky (otherwise they wouldn't be discreet either...), but you won't know on site. And if they notice you... Well,
geek the mage is a notion I never want to get to my enemies head when I'm playing a Mage ^^
For the rolls you'd have to see with Mercy, but with a force 6 spirit, you can take some drain there, so it could be important especially with the spirit whisperer quality which adds one resistance dice for the spirit.
It's the same thing if you want to cast a Force 6 invisibility for example, even more so that you'd have to cast it twice, once for you, once for the spirit (with a 2d sustain penalty).
This is even more important that it takes place before a combat situation.
When you do stuff at Force 4 or less it's not really an issue unless you're really unlucky, and since we don't want to roll for every little thing...
Another point to keep in mind is that you only have invisibility and not improved invisibility... There will be a lot of noise on the next day with all the footage of a mage flying through Seattle... And some of that footage is bound to be of reasonably good quality...
Speaking of karma, be careful, you put twice what you should have on your sheet, see
hereFor the rolls, you can use this:
http://orokos.com/For Shadowrun the codes are Xd6t5 where X is your dice pool, unless you pre-edge your roll, then it's Xd6h5.
