Monitoring of the Crab Nebula

Subsequent to the detection of a gamma ray flare in September, Chandra has been used to monitor the structure and spectrum of the Crab Nebula. This flare was first detected by AGILE (ATEL 2855)and had a timescale of days. The event was also seen with the Fermi Satellite. These S/C have also observed flaring at other times and with longer timescales. The Sept. event has received international attention and it appears that the flaring is not directly associated with the pulsar, but with the nebular flux. The timescale indicates an emitting region as small as 0.5-1.0 arcsec at two kpc. Chandra has shown that there are many features of this scale in the nebula and that they are constantly changing. It is essential that a viable baseline be established in order to obtain useful information from future observations triggered by another flare. We propose a series of monitoring observations.