The Swift X-ray Telescope

TL;DR

The Swift X-ray Telescope is a rapid-response instrument designed to quickly locate and observe Gamma-Ray Burst afterglows in X-ray wavelengths, providing precise positions, spectra, and lightcurves to advance GRB science.

Contribution

This paper introduces the design and capabilities of the Swift XRT, enabling prompt, automated X-ray observations of GRBs with high sensitivity and spectral measurement capabilities.

Findings

Rapid localization within 100 seconds of burst

Automated source detection within 5 seconds

Spectral and lightcurve measurements over days/weeks

Abstract

The Swift Gamma-Ray Explorer is designed to make prompt multiwavelength observations of Gamma-Ray Bursts (GRBs) and GRB afterglows. The X-ray Telescope (XRT) enables Swift to determine GRB positions with a few arcseconds accuracy within 100 seconds of the burst onset. The XRT utilizes a mirror set built for JET-X and an XMM/EPIC MOS CCD detector to provide a sensitive broad-band (0.2-10 keV) X-ray imager with effective area of > 120 cm^2 at 1.5 keV, field of view of 23.6 x 23.6 arcminutes, and angular resolution of 18 arcseconds (HPD). The detection sensitivity is 2x10^-14 erg cm^-2 s^-1 in 10^4 seconds. The instrument is designed to provide automated source detection and position reporting within 5 seconds of target acquisition. It can also measure the redshifts of GRBs with Fe line emission or other spectral features. The XRT operates in an auto-exposure mode, adjusting the CCD readout mode automatically to optimize the science return for each frame as the source intensity fades. The XRT will measure spectra and lightcurves of the GRB afterglow beginning about a minute after the burst and will follow each burst for days or weeks.