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 similar to 50 mu s, but at higher frequencies the pulses are very short, typically lasting only similar to 1-2 mu s. At each frequency, giant pulses are emitted only in narrow (less than or similar to 10 mu s) windows of pulse phase located similar to 55-70 mu s 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 greater than or similar to 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.