The Wide Field Imager Lyman-Alpha Search (WFILAS) for Galaxies at Redshift ~5.7: I. A Spatially Compact Lyman-alpha Emitting Galaxy at Redshift 5.721

We report the spectroscopic confirmation of a compact \lya emitting galaxy at \(z=5.721\). A FORS2 spectrum of the source shows a strong asymmetric line with a flux of 5\(\times10^{-17}\) erg s\(^{-1}\) cm\(^{-2}\), making it one of the brightest \lya emitting galaxies at this redshift, and a line-of-sight velocity dispersion of 400 km s\(^{-1}\). We also have a tentative detection of a second, narrower component that is redshifted by 400 km s\(^{-1}\) with respect to the main peak. A FORS2 image shows that the source is compact, with a FWHM of 0\farcs5, which corresponds to 3.2 kpc at this redshift. This source is a brighter example of \object{J1236.8+6215} \citep{Dawson02}, another \lya\ emitting galaxy at \(z\sim5.2\).