Chandra/ACIS Subpixel Event Repositioning. II. Further Refinements and   Comparison between Backside and Front-side Illuminated X-ray CCDs
  We further investigate subpixel event repositioning (SER) algorithms in application to Chandra X-ray Observatory (CXO) 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. 
Jingqiang Li, Joel H. Kastner, Gregory Y. Prigozhin, Norbert S.   Schulz, Eric D. Feigelson, Konstantin V. Getman