Jiamusi Pulsar Observations: I. Abnormal emission events of PSR B0919+06

PSR B0919+06 generally radiates radio pulses in a normal phase range. It is known for its occasional perplexing abnormal emission events wherein individual pulses come to an earlier phase range for a few tens of periods and then it returns to its usual phase. Heretofore, only a few such events have been available for study. We observed PSR B0919+06 for about 30 h using the Jiamusi 66-m telescope at the Jiamusi Deep Space Station at the S band, and we detected 92 abnormal emission events. We identify four types of events based on the abrupted or gradual phase-shifting of individual pulses. The abnormal emission events are seen to occur randomly about every 1000-3000 periods, and they affect the leading edge of the mean profile by up to 2 per cent in amplitude. The abnormal emission events are probably related to gradual changes of emission processing in the pulsar magnetosphere.