HETG/E0102/Cal - Pollock-HETG Comparison
Back to E0102 for Calibration

Comparing Pollock model and HETG data - 19 October 2006

Combining the Pollock spectrum (with its nominal linewidths) with a simple geometric model of E0102 (blastwave shell plus cylinder plus small dot - without any Doppler effects), the resulting simulated dispersed events can be compared with the real HETG-observed data. Plots were made that show the Data and Model events in 2D, and compare them along the dispersion direction using their 1D projections and a K-S test. The 1D projections have been slightly smoothed to reduce slight location mis-matches; the value of Chi is also shown in a tiny residual plot which has a range of +/-10.

Examples of the plots are shown on this page for the MEG minus-first order of obsid 3828; plots for obsid 3828 (MEG+/-1, HEG+/-1) and obsid 120 (MEG+/-1) are available in these files:

Note that the Model events have been "over-simulated" by a factor of 2 to help show the model structure more clearly and to reduce the model noise (a common Monte Carlo technique.) Gap regions between the ACIS readout chips are seen as zeroed-out strips in both Data and Model.

The agreement of Data and Model is very good given that the spectral model is being used as-provided - without even a norm adjustment; for example the Model/Data ratio of total counts in the plotted range for the obsid 3828 MEG minus first order is:
(53734/2) / 29280 = 0.917 .

Note that the HETG data, its processing, and the ARFs used are all "from the past" and do not include recent calibration updates. An update of this comparison using current processing and calibrations is work for the future.


HETG/MEG Data compared with a simple Model simulation for E0102. In the 1D histogram comparison the model (thin red line) and data (diamonds) agree well (10% level). The smaller residual plot, below the main histograms, has a plot-axis range of Chi = +/-10.
Note the slight extra flux in the data seen between the Ne X (12 A) and Ne IX (13.5 A) bright lines - this may be due to Fe emission not otherwise "covered" by the Pollock spectral model.

As above, but plotted with a linear counts/bin scale:

dd@space.mit.edu