This is an old listing of different web pages with HESSI or HESSI-related science topics and simulations. For the HESSI home page at GSFC, go to http://hesperia.gsfc.nasa.gov/hessi/. For the UCB HESSI home page, go to http://sprg.ssl.berkeley.edu/hessi/. For the HESSI European Data Center, go to http://www.hedc.ethz.ch/.

SIMULATIONS:

• HESSI Effective area calculations. New effective area calculations including the effects of shutters. Richard Schwartz, 21-Apr-1998.

• Preliminary Outline of the HESSI end-to-end test. The main purpose or the HESSI End-to-End Test (also called the "Imager Modulation Test" or the "gridlet test") is to show that the HESSI collimators, as mounted on the telescope tube, will modulate X-rays. At each stage of HESSI development, the test should be done under conditions and configurations as close as possible to those of flight. Ed Schmahl, Jan-1998.

• Imaging Spectroscopy. Simulations of the imaging capability of HESSI at different photon energies using the known parameters of its collimators and standard methods of RMC image reconstruction. Ed Schmahl, Jun-1997.

• Reconstruction of Point- and Extended Sources using Maximum Entropy Methods. These images show the effects of using only 2 or 4 HESSI collimators on mapping combined small and large sources. The motivation for this is to illustrate the tradeoffs required at high energies where only two grids will be thick enough to modulate photons. Ed Schmahl, 19-Dec-1997.

• The effect of varying grid thicknesses on HESSI photon transmission. Calculations of the high-energy photon transmission using different grid thicknesses, compared to the thicknesses used in the HESSI-SMEX proposal. Jim McTiernan, 21-Nov-1997.

• HESSI MEM test images using different grid models. Simulated HESSI images, for the 500 keV continuum and the 2.223 MeV line. All are generated using the Maximum Entropy Method (MEM). Jim McTiernan, 14-dec-1997.

• HESSI Sensitivity calculations using the newest grid thicknesses. The newest grid thicknesses and the resultant foldout figures for the PhaseA proposal. Richard Schwartz, 27-dec-1997.

• Molybdenum as a possible HESSI window material. Almost any material with the Z of aluminum, or greater, would do to a first approximation as an entry window for HESSI hard X-ray imaging. This is because the photoeffect dominates the total absorption cross-section out to 30 keV or higher, so that all of the unwanted solar thermal emission can be suppressed sharply. However, this said, which material? This note offers Mo (Z=42) as an alternative. Hugh Hudson, 6-Jan-1998.

RELATED DATA:

• Examples of HEIDI SAS Data. Plots of SAS data from the HEIDI Balloon Flight, June 22, 1993. Ed Schmahl, 23-Dec-1997.

• Yohkoh HXA data. HXA is the aspect system for the HXT instrument on Yohkoh, the Yohkoh analog of the HESSI SAS. Hugh Hudson, 22-dec-1997.

• More Yohkoh HXA data. A recent set of HXA scans obtained from Yohkoh. The X and Y coordinates are tilted at 45 degrees from solar NS. The notches in the scans are due to shadows of fiducial grids mounted on the rear grid plane of the HXT telescope itself. The locations of the limbs and of the fiducial marks are determined in hardware on board Yohkoh by a simple threshold identification. Also includes the IDL code that generated the figures. Hugh Hudson, 18-Feb-1998.

SCIENCE ISSUES:

• Notes on Reconstruction Software. Important issues about simulation and image reconstruction software that should be discussed by the interested parties on the HESSI team. Ed Schmahl, Dec-1997.

DOCUMENTATION:

• HESSI Documentation. A current list of the files and directories in the /hessidoc directory, on hesperia.gsfc.nasa.gov.

Back to Top?

Updated, 6-Jan-1998, J.McTiernan

Comments to: jimm@ssl.berkeley.edu