We present evidence that the very-high-energy ( VHE , E > 100 \textrm { GeV } ) gamma-ray emission coincident with the supernova remnant IC 443 is extended .
IC 443 contains one of the best-studied sites of supernova remnant/molecular cloud interaction and the pulsar wind nebula CXOU J061705.3+222127 , both of which are important targets for VHE observations .
VERITAS observed IC 443 for 37.9 hours during 2007 and detected emission above 300 \textrm { GeV } with an excess of 247 events , resulting in a significance of 8.3 standard deviations ( \sigma ) before trials and 7.5 \sigma after trials in a point-source search .
The emission is centered at 6 ^ { \textrm { h } } 16 ^ { \textrm { m } } 51 ^ { \textrm { s } } +22 \textrm { \textdegree } 30 ^ { \prime } % 11 ^ { \prime \prime } ( J2000 ) \pm 0.03 \textrm { \textdegree } _ { stat } \pm 0.08 \textrm { \textdegree } _ { sys } , with an intrinsic extension of 0.16 \textrm { \textdegree } \pm 0.03 \textrm { \textdegree } _ { stat } \pm 0.04 \textrm { % \textdegree } _ { sys } .
The VHE spectrum is well fit by a power law ( dN / dE = N _ { 0 } \times ( E / \textrm { TeV } ) ^ { - \Gamma } ) with a photon index of 2.99 \pm 0.38 _ { stat } \pm 0.3 _ { sys } and an integral flux above 300 GeV of ( 4.63 \pm 0.90 _ { stat } \pm 0.93 _ { sys } ) \times 10 ^ { -12 } \textrm { cm } ^ { -2 } \textrm { % s } ^ { -1 } .
These results are discussed in the context of existing models for gamma-ray production in IC 443 .