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We study 27-day variations of the galactic cosmic ray (GCR) intensity for2005- 2008 period of the solar cycle #23. We use neutron monitors (NMs) datacorrected and uncorrected for geomagnetic disturbances. Besides the limitedtime intervals when the 27-day variations are clearly established, always existsome feeble 27-day variations in the GCR 5 intensity related to the constantlypresent weak heliolongitudinal asymmetry in the heliosphere. We calculate theamplitudes of the 27-day variation of the GCR intensity based on the NMs datacorrected and uncorrected for geomagnetic disturbances. We show that theseamplitudes do not differ for NMs with cut-off rigidities smaller than 4-5 GVcomparing with NMs of higher cut-off rigidities. Rigidity spectrum of the27-day variation of the GCR intensity found in the uncorrected data is softwhile it is hard in the case of the corrected data. For both cases existsdefinite tendency of softening the temporal changes of the 27-day variation'srigidity spectrum in period of 2005 to 2008 approaching the minimum of solaractivity. We believe that a study of the 27-day variation of the GCR intensitybased on the data uncorrected for geomagnetic disturbances should be carriedout by NMs with cut-off rigidities smaller than 4-5 GV.

27-day variation of the GCR intensity based on corrected and uncorrected for geomagnetic disturbances data of neutron monitors