  To constrain the giant pulse (GP) emission mechanism and test the model of
Lyutikov (2007) of GP emission, we are carrying out a campaign of simultaneous
observations of the Crab pulsar between gamma-rays (Fermi) and radio
wavelengths. The correlation between times of arrival of radio GPs and
high-energy photons, whether it exists or not, will allow us to choose between
different origins of GP emission and further constrain the emission physics.
Our foremost goal was testing whether radio GPs are due to changes in the
coherence of the radio emission mechanism, variations in the pair creation rate
in the pulsar magnetosphere, or changes in the beaming direction. Accomplishing
this goal requires an enormous number of simultaneous radio GPs and
gamma-photons. Thus, we organized a radio observations campaign using the 42-ft
telescope at the Jodrell Bank Observatory (UK), the 140-ft telescope, and the
100-m Robert C. Byrd Green Bank Telescope (GBT) at the Green Bank Observatory
(WV). While the observations with the two first ones are ongoing, here we
present the preliminary results of 20 hrs of observations with the GBT at the
high frequency of 8.9 GHz. These particular observations were aimed to probe
the model of GP emission by Lyutikov (2007) which predicts that GPs at
frequencies > 4 GHz should be accompanied by gamma-ray photons of energies of
1-100 GeV.
