We report on the observation of \gamma -rays above 25 GeV from the Crab pulsar ( PSR B0532+21 ) using the MAGIC I telescope .
Two data sets from observations during the winter period 2007/2008 and 2008/2009 are used .
In order to discuss the spectral shape from 100 MeV to 100 GeV , one year of public Fermi Large Area Telescope ( Fermi -LAT ) data are also analyzed to complement the MAGIC data .
The extrapolation of the exponential cutoff spectrum determined with the Fermi -LAT data is inconsistent with MAGIC measurements , which requires a modification of the standard pulsar emission models .
In the energy region between 25 and 100 GeV , the emission in the P1 phase ( from -0.06 to 0.04 , location of the main pulse ) and the P2 phase ( from 0.32 to 0.43 , location of the interpulse ) can be described by power laws with spectral indices of -3.1 \pm 1.0 _ { stat } \pm 0.3 _ { syst } and -3.5 \pm 0.5 _ { stat } \pm 0.3 _ { syst } , respectively .
Assuming an asymmetric Lorentzian for the pulse shape , the peak positions of the main pulse and the interpulse are estimated to be at phases -0.009 \pm 0.007 and 0.393 \pm 0.009 , while the full widths at half-maximum are 0.025 \pm 0.008 and 0.053 \pm 0.015 , respectively .