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                                    NUSTAR
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NuSTARDAS v1.8.0 software patch:

Note that the CALDB patch 20170727 is required when using the new 'saacalc=3' mode.

- nucalcsaa:

  Add new 'saacalc=3' operation mode.  This accounts for the changes in the
  internal background related to the evolution of the South Atlantic Anomaly
  (SAA) throughout the solar cycle. This improves on the 'saacalc=2', though
  users should check the background filtering reports provided by the NuSTAR
  SOC (http://www.nustar.caltech.edu/page/background) when deciding which
  filter parameters to use.

  Improve handling of input cleaned event files.  This patch adjusts the
  behavior of nucalcsaa so that the fselect FTOOL is no longer run if the
  SHIELD column is not present in the cleaned event file. The SHIELD column
  is truncated when the 'cleancols=no' keyword is used by nupipeline, which
  is the default case.

- nuexpomap:

  Improve the evaluation method for calculating the time-averaged optical
  axis location. Before the change, the brightest point on the vignetting-
  corrected exposure map could be off from the time-averaged optical axis
  position by up to 10". This has been fixed and the two locations will
  now correspond to each other. This change affects only the vignetting
  corrected exposure map, which is used in the light curve generation.
  It has no impact on the ARF and RMF generation.

- nuscreen:

  Suppress warning messages that occur when a particular event mode does
  not contain any exposure time and therefore its associated cleaned event
  file is not generated. This commonly occurs for several of the available
  data modes (i.e., calibration source data, slew data, and/or data
  obtained during the SAA passages).

- numkarf:

  Improve effective area calculation for the extended sources in the
  'flatflag=yes' case.  In the 'flat' ARF case, where the effective area
  is not weighted by the observed count rate, the effective areas were
  before evaluated with the same weight in each box that covered the
  extraction region, regardless of how much area of each box was actually
  contained in the extraction region. This was particularly sensitive to
  gaps between the CZT detectors that were inside the boxes but outside
  the extraction region. To obtain a more accurate effective area, we
  now weigh the effective areas with the covering region of each box.
  This change only influences the 'flatflag=yes' case.

- nupipeline:

  Now supports the keywords for the handling of the new case 'saacalc=3'
  of the module nucalcsaa.