HETG-related Analysis Reference Data

HETGS Analysis Reference Data

Here are all known inputs to flight processing that must be be generated from and validated by HETG calibration activites. Note that HETG-relevant equations are also listed here.

• Coordinate systems (McDowell, http://hea-www.harvard.edu/ asclocal/sds/CDR2/coords.ps) uses the following:

  HETG Periods, Angles

  HETG location

  grating equation

  
  
• Level 1 processing (including par files, FITS headers) (do/should/will) include:

  tg_foc_len [mm]

  The on-axis HETG-to-HRMA_focus distance (Rowland spacing).

  
  
• Dave H's L1.5_devel/rd.pro uses, in additon to Level 1 outputs, the following:

  R_TG_MEG, R_TG_HEG [mm]

  Effective MEG and HEG ring-of-gratings radii. Used to calculate cross-dispersion astigmatism size estimate.

  astigmatism equation

  peak-to-peak astigmatic image size equation

  meg_angle, heg_angle [degrees]

  The dispersion axis clocking angles for HEG and MEG in the data. HETG will supply these angles w.r.t. facility (Chandra or XRCF) to be combined with detector-to-facility angle.

grating equation

m lambda = p sin(beta)

meg_period, heg_period [A]

The average grating periods.