[en] The horizontal and vertical emittance of the Cornell Electron Storage Ring (CESR) was determined by measuring the emitted radiation from an Advanced Photon Source (APS) prototype short period (3.3 cm) 123-pole undulator. During this run, CESR storage ring parameters were modified to allow operation in a dedicated low-emittance mode which mimicked the APS storage ring characteristics. The intrinsic smaller opening angle of undulator radiation makes it appropriate for low emittance beams. A two-dimensional Charged Couple Device (CCD) detector coupled with an upstream scanning slit was used to scan the emitted radiation This has the advantage of a rapid data collection. Further, this technique also allows us to measure the emittance in the fixed/scanning technique where the first slit acts as the aperture of a pinhole camera and the size of the image is measured with the CCD