Do PhysAds leave astral sigs behind when they use their powers?

For example, an adept kills a guard with Killing Hands. Does he/she leave a traceable "residue" that magic users can notice?

well ask your GM I think in the end it's really up to him if he wanted to include it or not.

Standard rules do not describe a PhysAd leaving an Astral Sig behind. In addition, where it talks about erasing an Astral Signature (SR3.172 top right corner), it appears to me to list all the things that produce astral signatures. The only things on that list are spirits and spells.

Feel free to do a search if you want to read this argument a few times, it's happened on these boards a couple times. In the end, we've always had to agree to disagree, i.e. ask your GM.

Adepts using the power of Dealay Damage leave a astral charge on the opponents Aura, thats about all i know.

Astral signatures are left behind when actively using a Magical Skill. Most adept powers don't rely on Magical Skills, they're instead "grounded" into the adept himself allowing him to improve his natural abilities. Thus most of them don't leave a signature behind. They also don't have any Force ratings, so even if they did a whole new set of rules would have to be created to judge how long and how potent a signature they were.

That said, I'd say that any power that directly affected another person with a magical effect would leave a signature behind. Precious few powers do that, however, beyond Distance Strike, Delay Damage, and maybe (but doubtfully) Nerve Strike. I'd then use half the adept's Magic Rating as the effective Force of the power, reflecting that at least half of the magic of the power was grounded into the adept himself rather than the target.

Uses of Centering would likely leave a signature behind, however, since it requires a Magical Skill. But since it only affects the adept, the signature would be on his own aura where its already there so its a moot point. In essence, that's what's happening with the vast majority of all adept powers; since they only affect the adept, they're not "left behind" anywhere... they're all with him. So a really good assensing test on the adept himself will reveal what powers he has, but that's about the only place you'll discover them.

Hmm... so does using sorcery as a combat skill in astral combat leave an astral sig? If so, why? Specifically, why would using sorcery in that regard leave an astral sig, while *not* using sorcery wouldnt?

It would, but you're using it to augment yourself so it's not going to leave a signature on anything but you. Just like most spells that affect the caster himself. But don't look at me. I didn't come up with the rules, I'm just pointing them out.

My guess for Sorcery (Astral Combat) is that Sorcery, itself, is targeted mostly around focusing your willpower. You're effectively augmenting your natural ability to harm an astral opponent with your magic along the same way a decker or otaku can spontaneously attack another icon using nothing but their Computer skill without actually having an Attack Utility (spell) handy.