revised 4/15/99, 5/3/99 back to HETG HSI Analyses

Fitting the B-K depression

To measure the QE depression value in the B-K image, a straight line was fit between subregions of the B-K projected LRF which were uneffected by the depression (asterisks in top panel). The ratio of measured counts to the line fit value was then fit to a horizontal line (nominally at 1.0) and a Gaussian depression (illegible center panel, replotted in lower panel).

     Fitting results
 
  i       ctr    dctr      hght     dhght       sig     dsig      area     darea
  1  2043.046  1.0697     -0.17     0.013   12.1442   1.2423     -2.67    -0.342
 
  Cont=      1.00    dCont=      0.01        Chisq=      1.08
The Gaussian "hght" of -0.17 corresponds to a QE depression value of 0.83, averaged over the events selected.

Checking the correction technique

Setting the QE depression value to 0.83 (in hsi_qe_depress.pro) and using statistial creation of the missing events yields a good fit to just the straight line.

 QE_DEPRESS =  0.830 :
 Candidates for correction:        87665
 Candidates added:         2618

    Fitting results
 
  i       ctr    dctr      hght     dhght       sig     dsig      area     darea
  1  2043.184  0.7665     -0.09     0.036    1.6701   0.7082     -0.19    -0.110
 
  Cont=      1.01    dCont=      0.00        Chisq=      1.33

The above analyses were carried out in the procedure hsi_B_tile_anal.pro.


This web page is: http://space.mit.edu/HETG/hsi/B-K_tile_anal.html
Please send any comments and updates: send e-mail to dd@space.mit.edu.