Multifrequency Observations of Giant Radio Pulses from the Millisecond Pulsar B1937+21

Giant pulses are short, intense outbursts of radio emission with a power-law intensity distribution that have been observed from the Crab pulsar and PSR B1937+21. We have undertaken a systematic study of giant pulses from PSR B1937+21 using the Arecibo telescope at 430, 1420, and 2380 MHz. At 430 MHz, interstellar scattering broadens giant pulses to durations of ~50 μs, but at higher frequencies the pulses are very short, typically lasting only ~1-2 μs. At each frequency, giant pulses are emitted only in narrow (<~10 μs) windows of pulse phase located ~55-70 μs after the main and interpulse peaks. Although some pulse-to-pulse jitter in arrival times is observed, the mean arrival phase appears stable; a timing analysis of the giant pulses yields precision competitive with the best average profile timing studies. We have measured the intensity distribution of the giant pulses, confirming a roughly power-law distribution with approximate index of -1.8, contributing >~0.1% to the total flux at each frequency. We also find that the intensity of giant pulses falls off with a slightly steeper power of frequency than the ordinary radio emission.