Original calc is here. LordXcano assumed 8 j/cc as the fragmentation value of the meteor. However, meteorites are made of kamacite, according to Antoniofer, which is an iron-nickel alloy.
Fragmentation of kamacite varies from 1-5 j/cc, according to this.
As LordXcano calculated, the volume is 3.21e+20 cc.
3.21e+20*1 = 3.21e+20 Joules, Island level+
3.21e+20*5 = 1.605e+21 Joules, Large Island level
Slight downgrade from Large Island level+ to Island level+ or Large Island level, depending on which end is preferable.
It's better to use 3 j/cc as a mid-end.
3.21e+20*3 = 9.63e+20 Joules, Large Island level