Chandra ACIS subpixel event repositioning: Further refinements and comparison between backside- and frontside-illuminated X-ray CCDs

We further investigate subpixel event repositioning (SER) algorithms in application to Chandra X-Ray Observatory (Chandra) CCD imaging. SER algorithms have been applied to backside-illuminated (BI) Advanced CCD Imaging Spectrometer (ACIS) devices and demonstrate spatial resolution improvements in Chandra ACIS observations. Here a new SER algorithm that is charge split-dependent is added to the SER family. We describe the application of SER algorithms to frontside-illuminated (FI) ACIS devices. The results of SER for FI CCDs are compared with those obtained from SER techniques applied to BI CCD event data. Both simulated data and Chandra ACIS observations, of the Orion Nebular Cluster were used to test and evaluate the achievement of the various SER techniques.