UPDATE: See also my page on the Chandra Orion Ultradeep Project
This image shows a ROSAT HRI-observation of the Orion nebula region (data taken from the ROSAT data archive; see Gagne et al. 1995, ApJ 445, 280 for a detailed analysis). The field of view is about 40 x 40 arcmin, the image is centered on the Trapezium. The very strong source near the upper edge is the star P1724. This star showed a giant X-ray flare during the ROSAT observation, probably the most energetic X-ray flare ever observed. (For details see the abstract of our A&A paper on this flare).
The next image shows a mosaic created by combining a dozen ROSAT PSPC pointings. The field of view is about 6 by 9 square-degrees and includes the Orion nebula cluster near the center and the cluster of young stars around sigma Ori near the top left edge.