XMM-NEWTON SCIENCE DATA IMAGES
The images in this XMM-Newton gallery have been created using the ESAS tasks in SAS. The individual observations have been temporally filtered to remove periods of strong soft proton contamination and then corrected for the quiescent particle background and the residual soft proton background. The images have been been corrected for exposure and the effects of possible different filters on the three EPIC instruments. Finally, the images have been adaptively smoothed. The processing methodology was discussed extensively in Snowden et al. 2008, and the use of the SAS ESAS tasks is explained in the ESAS Handbook.
The images are processed in three bands, 0.4-0.75 keV, 0.75-1.3 keV, and 2.0-7.2 keV. For each object there are jpeg images in the three individual bands, a combined soft band (0.4-1.3 keV), and a false-color image (red: 0.4-0.75 keV, green: 0.75-1.3 keV, blue: 2.0-7.2 keV). FITS images for the three bands are also available. For each object there is a list of individual observations (ObsIDs) that cover the field. ObsIDs with '**' in the second column have been used for the mosaic, a 'c' in the second column indicates that the ObsID was too strongly contaminated by soft protons to be useful.
Images at other Wavebands: Some objects have either DSS or WISE 22 micron images on the same scale as the X-ray false-color images. These are generated using the HEASARC SkyView facility.
Caveats: The objects have been processed uniformly on a 'good-enough' basis. Some individual observations could probably benefit from a more stringent data reduction and certain other observations are so strongly affected by residual soft proton events that there is some effect noticeable in the mosaicked image. This is most readily seen in the hard band images where there is little emission from the object. The SNR RXJ1713-3941 and the galaxy cluster Abell 2256 are good example of this effect.
A second source of processing artifacts originate in the mosaicking process. In order to combine data from different instruments and possibly different filters a spectrally dependent scaling must be used. If the source spectrum is significantly different from the assumed spectrum a mismatch can occur. This doesn't happen often, but the false-color image of the Perseus cluster shows some evidence for it.
A third artifact can be seen when exposure varies significantly across the field. In this case the scale length of the adaptive smoothing will vary leading to a variable clumpiness in the image. The image of S308 is a good example of this effect as the central pointing has an order of magnitude higher exposure than the outer pointings.
And an Invitation: Creation of the Science Image Gallery
will be a long-term project pursued as time allows. The order as to which
observations are done first is arbitrary and if you have a request, let the
GOF know through our Help Desk at: xmmhelp@athena.gsfc.nasa.gov.
Credit: Steve Snowden NASA/GSFC
