We report on a bright flare in the Crab Nebula detected by the Large Area Telescope ( LAT ) on board the Fermi Gamma-ray Space Telescope .
The period of significantly increased luminosity occurred in 2013 March and lasted for approximately 2 weeks .
During this period , we observed flux variability on timescales of approximately 5 hours .
The combined photon flux above 100 MeV from the pulsar and its nebula reached a peak value of ( 12.5 \pm 0.8 ) \cdot 10 ^ { -6 } cm ^ { -2 } s ^ { -1 } on 2013 March 6 .
This value exceeds the average flux by almost a factor of 6 and implies a \sim 20 times higher flux for the synchrotron component of the nebula alone .
This is the second brightest flare observed from this source .
Spectral and temporal analysis of the LAT data collected during the outburst reveal a rapidly varying synchrotron component of the Crab Nebula while the pulsar emission remains constant in time .