Spatial corrections of ROSAT HRI observations
Abstract
X-ray observations with the ROSAT High Resolution Imager (HRI) often have spatial smearing on the order of 10arcsec te[(Morse 1994).]{mor94} This degradation of the intrinsic resolution of the instrument (5arcsec ) can be attributed to errors in the aspect solution associated with the wobble of the space craft or with the reacquisition of the guide stars. We have developed a set of IRAF/PROS and MIDAS/EXSAS routines to minimize these effects. Our procedure attempts to isolate aspect errors that are repeated through each cycle of the wobble. The method assigns a ``wobble phase" to each event based on the 402 second period of the ROSAT wobble. The observation is grouped into a number of phase bins and a centroid is calculated for each sub-image. The corrected HRI event list is reconstructed by adding the sub-images which have been shifted to a common source position. This method has shown ~ 30% reduction of the full width half maximum (FWHM) of an X-ray observation of the radio galaxy 3C 120. Additional examples are presented.
- Publication:
-
Astronomy and Astrophysics Supplement Series
- Pub Date:
- December 1998
- DOI:
- 10.1051/aas:1998333
- arXiv:
- arXiv:astro-ph/9811121
- Bibcode:
- 1998A&AS..133..431H
- Keywords:
-
- TECHNIQUES: IMAGE PROCESSING;
- X-RAYS: GENERAL;
- Astrophysics
- E-Print:
- AandA latex (6 pages with 7 embedded postscript figures). Scheduled for publication in the 1 Dec issue of Astron. Astrophys. Suppl. Series