SIMBAD references

We report on the discovery of drifting subpulses from the Vela pulsar, observed using the Yunnan 40 m radio telescope at 6800 MHz observing frequency. The single pulses show the presence of two distinct drifting patterns, where the central component is modulated in longitude and amplitude simultaneously with a period of 9 pulses, and the trailing component remains phase stationary within the pulse window but periodically changes in intensity with a period of 29 pulses. The leading component emission remains constant in intensity and pulse phase. Such periodic modulation in the Vela pulsar is a separate phenomenon from periodic nulling and traditional subpulse drifting, which may lead to a greater understanding of the pulse emission mechanism.