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We study time‐resolved spectra of the prompt emission of  Swift γ‐ray bursts (GRB). Our goal is to see if previous BATSE claims of the existence of a large amount of spectra with the low‐energy photon indices harder than 2/3 are consistent with  Swift  data. We perform a systematic search of the episodes of the spectral hardening down to the photon indices  ≤2/3  in the prompt emission spectra of  Swift  GRBs. We show that the data of the Burst Alert Telescope (BAT) instrument on board of  Swift  are consistent with BATSE data, if one takes into account differences between the two instruments. Much lower statistics of the very hard spectra in  Swift  GRBs are explained by the smaller field of view and narrower energy band of the BAT telescope.

Where are Swift γ‐ray bursts beyond the ‘synchrotron deathline’?