Magical Radar - Unwitting Request for Theory

[nkafkafi]

No: HPFGUIDX 89347

<bboy_mn at y...> wrote:
<snip>
> Detection of Magic-
> 
<big snip>
> The wizards monitoring magic occurrences at the Ministry of Magic 
are
> able to detect magical events. That allows them to closely monitor
> specific locations like Harry's (actually the Dursley's) house. If
> that magic exceeds a particular threshold, it then appears on Magic
> 'Storm' radar. 
> 
> When substantial bursts of magic occur or magic events occur at
> critical locations, that may automatically trigger more 
sophisticated
> magical detectors that can divine the nature of the magic that
> occurred. This would allow the Ministry of Magic to dispatch
> Accidental Magical Reversal Teams and Teams of Obliviators very
> quickly to deal with dangerous magical events.
<Hagrid size snip>
> 
> Is there anything I left out?
> 

Neri replies:

An interesting question you left out, and was actually raised by 
Abbet several days ago (#89149) is why the same radar doesn't detect 
the use of unforgivable curses. It would be reasonable to assume that 
unforgivables have a strong and unique radar signature.

My guess is that, like real radar, magic radar can be blocked, 
fooled, jammed, etc. Any bad guy worth his salt probably carries some 
kind of illegal stealth device. Underages are not likely to come by 
them, although I won't be surprised if Arthur Weasley installed such 
a device (captured in one of his raids, no doubt) in the Borrow, so 
he can experiment with bewitching muggle cars and the like without 
being asked embarrassing questions. This might help explaining how 
the twins got off so easily.  

Neri