# Descattering of Giant Pulses in PSR B1957+20

## TL;DR

This paper demonstrates that giant pulses from PSR B1957+20 can be used to directly measure and descatter the interstellar scattering response, revealing intrinsic pulse durations and scattering screen properties.

## Contribution

It introduces a method to coherently descatter giant pulses, enabling direct measurement of the scattering impulse response and constraining the scattering screen structure.

## Key findings

- Scattering timescale is 12.3 microseconds.
- Descattered pulse power is confined within ~200 nanoseconds.
- Response decorrelates over 84 seconds.

## Abstract

The interstellar medium scatters radio waves which causes pulsars to scintillate. For intrinsically short bursts of emission, the observed signal should be a direct measurement of the impulse response function. We show that this is indeed the case for giant pulses from PSR B1957+20: from baseband observations at 327 MHz, we demonstrate that the observed voltages of a bright pulse allow one to coherently descatter nearby ones. We find that while the scattering timescale is $12.3\,\mu$s, the power in the descattered pulses is concentrated within a span almost two orders of magnitude shorter, of $\lesssim\!200\,$ns. This sets an upper limit to the intrinsic duration of the giant pulses. We verify that the response inferred from the giant pulses is consistent with the scintillation pattern obtained by folding the regular pulsed emission, and that it decorrelates on the same timescale, of~$84\,$s. In principle, with large sets of giant pulses, it should be possible to constrain the structure of the scattering screen much more directly than with other current techniques, such as holography on the dynamic spectrum and cyclic spectroscopy.