D..20 February, 2004 (AE Version 3.19)

• AE now requires the ``February, 2004'' or later version of the IDL Astronomy User's Library (http://idlastro.gsfc.nasa.gov/).

• PSF images (used to construct extraction polygons, compute PSF fractions, refine source positions, and reconstruct images) have been significantly improved by using smaller pixel sizes on axis, and by using the most appropriate CALDB PSF library (f1, f2, or f3) for each source.

• Significant improvements in the accuracy of the PSF fractions (which affect the shape of the ARFs) have been accomplished by better estimating the total power in each PSF image ( the integral of the PSF out to infinity)¹⁸.
  • AE is now careful to request from mkpsf an image size large enough to avoid cropping the library images.
  • AE now estimates the fraction of the power that is missing from PSF images derived from the f1 and f3 libraries (which have small fields of view) by using the f2 library (which has a larger field of view).
  The figure below shows the difference in PSF fractions computed by AE versions 3.4 and 3.19 for 1600 I-array sources.

  Figure 18: Ratios of PSF fractions computed by AE versions 3.4 and 3.19 for 1600 I-array sources.

  

• AE will now print a warning when the source extraction region falls outside the field of view of the PSF images so the observer will know that the PSF fraction is underestimated.

• Allowed values for keywords EXTRACTION_NAME (§7.3) and HDUNAME (§7.18) have been expanded.

• New keywords have been added: /REGION_ONLY (§7.6), /PIPELINE_RANDOMIZATION (§7.6), INDEX_FILE (§7.8), /SKIP_RECONSTRUCTION (§7.17).

• Revised blurring level applied to PSF images for the case of no pipeline randomization from 0.21 to 0.27 arcsec (based on CXC Helpdesk ticket #6819)--see §5.2.