HEASARC Staff Scientist Position - Applications are now being accepted for a Staff Scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details.

Goddard Space Flight Center   Help/FAQ
  What's New
  HEASARC Site Map
  NASA Homepage

HEASARC HOME ROSAT HOME ARCHIVE DATA ANALYSIS PROPOSALS & TOOLS STUDENTS / TEACHERS / PUBLIC
ROSAT Guest Observer Facility
ABOUT ROSAT GOF SERVICES WHAT'S NEW TIMELINES & MISSION INFO RELATED SITES GALLERY

Why do the hardness ratios differ from table to table in the SASS output?

(5/14/92)

The hardness ratios are calculated at various steps in the SASS processing. The hardness ratios present in the file *_hrd.asc arise from integrating the source spectrum, but WITHOUT a vignetting correction. These ratios are believed to be somewhat unreliable. The hardness ratios present in the files *_mas.asc and *_dsa.asc should agree. Both arise from the maximum likelihood detection algorithm, and should be relatively trustworthy. The flux and significance are found in each band, and each photon is weighted by a gaussian approximation to the PSF.

button Select another question related to this topic

Select another FAQ topic Select another FAQ topic Return to the ROSAT GOF Return to the ROSAT GOF

Please use the Feedback link if you have questions on ROSAT.

This file was last modified on Friday, 27-Jul-2001 14:57:43 EDT

NASA Astrophysics

  • FAQ/Comments/Feedback
  • Education Resources
  • Download Adobe Acrobat
    		• A service of the Astrophysics Science Division (ASD) at NASA/ GSFC

    ROSAT Project Scientist: Dr. Robert Petre

    Responsible NASA Official: Dr. Andy Ptak

    Privacy Policy and Important Notices.