The X-Ray Telescope

Swift's X-Ray Telescope (XRT; Burrows, et al. 2005, SSRv, 120, 165) is designed to measure the fluxes, spectra, and light curves of GRBs and their afterglows over a wide dynamic range covering more than seven orders of magnitude in flux. The XRT will pinpoint GRBs to 5-arcsecond accuracy within ten seconds of it target acquisition for a typical GRB, and will study the X-ray counterparts of GRBs beginning 60-80 seconds after the burst discovery and continuing for days to weeks. Table 6 summarizes the XRT parameters. More detail about the XRT can be found in Burrows et al. (2005, Sp. Sci. Rev., 120, 165).

Table 5: Characteristics of the XRT.

XRT Parameter	Value
Energy Range	0.2-10 keV
Telescope	Wolter 1
Detector	E2V CCD-22
Effective Area	120 cm$^2$ at 1.5 keV
Detector Operation	Photon-counting, integrated imaging, and timing
Field of View	$23.6 \times 23.6$ arcminutes
Detector Elements	$600 \times 602$ pixels
Pixel Scale	2.36 arcseconds
Telescope PSF	18 arcseconds HPD at 1.5 keV
	22 arcseconds HPD at 8.1 keV
Sensitivity	$8 \times 10^{-14}$ erg cm$^{-2}$ s$^{-1}$ in 10 000 s