ACIS Gain Calibration in HETGS Observation 1318 (Capella)
  7/14/00-dd

  The web directory http://space.mit.edu/HETG/technotes/acis_energy
contains files created from the recently reprocessed obsid 1318.
The file names and their description are given here:

obsid_1318-APabs_meas_lines_plots.ps
 Two plots:
  The upper plot is the ratio of E_ACIS/E_HETG for bright lines
in the first-order spectra.  The ACIS-S FI device data points are
plotted as diamonds and show a trend from a value of 0.99 above
1.2 keV to a valeu of 1.05 at 0.7 keV [the 9/16/99, N0004 gain
file was used in the processing.]
S1, a "+" symbol, shows values in the 0.95 to 1.05 range.
S3, a "*" symbol, shows a trend from 0.98 to 1.0 from 2.0 to 1.5 keV.
  The lower plot shows the same ratios plotted versus CHIPX and
the variation of S1 error with quadrant is visible.

obsid_1318-APabs_meas_lines.ps
 Many pages of plots: these pages show the actual events that
were measured and show a histogram of the ACIS ENERGY with the
HETG energy show by the solid vertical line and the ACIS energy
of the peak with the dashed vertical line.

obsid_1318-APabs_meas_lines.rdb
 An rdb file of the measurement results.  It was created by
running the HAK obs_anal.pro followed by meas_lines_on_acis.pro.

obsid_1318-APabs_Sky_orderselect.gif
 The "order selection" plot from the HAK analysis.  S1 wiggles
are clearly visible and is general trend of FIs to have higher
assigned energy at lower energies.