2.4 AE Version 2012-03-19

• ACIS event lists contain a boolean flag column named STATUS that CIAO uses to record various data cleaning criteria that are commonly used to remove events likely to arise from the instrumental background. Historically, two of those cleaning criteria--``afterglow'' identification and ``5x5 background'' identification--produce false positives for sources with high count rates. Thus, low-rate sources are optimally extracted by applying these cleaning criteria and high-rate sources are optimally extracted by ignoring these cleaning criteria (Broos et al., 2010).

  AE supports the optimal extraction of both groups of sources by applying a STATUS=0 filter to the source and background extractions of low-rate sources, and ignoring the STATUS column for high-rate sources. To take advantage of this capability, the observer should clean Level 2 event data (§7.3) using only the ``safe'' STATUS bits--those not associated with the ``afterglow'' and ``5x5 background'' criteria.

  Event lists supplied to AE must now include the STATUS column, whether you care about AE's conditional STATUS filtering or not.

• In the existing model-based algorithm for constructing background spectra (§7.6.1) and the existing model-based algorithm for masking point sources (§7.6.3), each point source model now includes the ACIS readout streak when it is bright.

• The set of plots produced by AE has been pruned to eliminate the less useful ones. Virtually all plots are now automatically saved as PostScript files.

• The new tool ae_interObsID_astrometry (§7.14.1) helps the observer verify the astrometric alignment of individual ObsIDs after an AE extraction has been performed.

• AE has been added to the Astrophysics Source Code Library. The citations we request (§4) for work that relies on AE has been updated.

• This release of AE is NOT yet compatible with MARX 5.0. I will certainly let you know when I have updated AE, but I do not have a good estimate of when that will occur.

• This release of AE has NOT been tested under CIAO 4.4. I will certainly let you know when I have exercised AE with this new version of CIAO.

• AE now requires the ``2012mar19'' or later version of the TARA package.

• AE now requires the AstroLib version dated 2011 October or later.

• AE now requires XSPEC version 12.7.0 or higher, because the AE fitting scripts now expect that the cplinear model (§7.11) is built into XSPEC, rather than compiled locally by the observer.

• Our own recipe for using AE (§7.1) has been significantly revised.

• Because the scope of AE and its level of automation have evolved over time, the AE manual had become poorly organized--giving too much emphasis to low-level AE components that are no longer commonly called directly by the observer. I have attempted to re-organize the Using ACIS Extract section to better describe the interfaces to AE that the modern observer is likely to use. I'm sure the manual could be better still, in countless ways. By the end of the Chandra mission I may perhaps have finally explained clearly how to use AE!

• The input parameter S_AIMPOINT has been eliminated; AE now infers the aimpoint using the SIM position.