Iridium 47 flare & question

finn@main.jetnet.ab.ca
Fri, 20 Mar 1998 13:58:06 -0700 (MST)

After days/ages of nothing but magnitude 1 and 0 flares, last night Iridium
47 flared at -5. I spotted it as it slowly became visible and then it got
brighter and brighter until it reached it's peak. It was quite impressive.
It only lasted for about 2-3 seconds but i was able to track Iridium 47 for
10-15 seconds after that. The total time the satellite was visible was about
30-40 seconds.

The question i ask is, looking at predicted flare magnitudes, i see some
listed at 0 while others are list as -0. What is the difference?  Is a -0.1
considered as -0? If that's the case, how far does the decimal place go? 

Jari