Format of the Catalog

• Summary of Chandra Observations: Lists the sequence number, obsid, live time, date of the start of the observation, and aimpoint of the observation.
  
  
• Chandra Event File: We have extracted the region or chip that contains the remnant, filtered the level 1 event file to remove times with elevated backgrounds, and retain only acis events with grades 0,2,3,4,6. The background filter is sometimes different than that used by the Chandra processing to make an evt2 file.
  
  The evt2 event files with and without high-background times can be downloaded by Netscape users by pressing the shift and left mouse button together. The larger file contains data from all chips. The smaller file contains data only from the chip containing the SNR.
  
  
• Chandra Counts and Fluxes: are given in 3 energy ranges. The boundary between hard and soft bands is 2.1 keV, the energy of the iridium absorption edge in the Chandra mirrors.
  
  The "absorbed" flux is that measured at the detector. The "unabsorbed flux" or "flux" is a calculation of the flux without interstellar absorption. This flux and the luminosity have been calculated using a column density derived by spectral fit and a distance from the literature. Click on "fit details" to see the spectral model and the fit obtained.
  
  
• Chandra Images: Images of each energy band: A pi-bin spectrum shows, in red, the energy range used for each image. The left image is the "raw" energy-filtered image. The right hand image has been smoothed with a gaussian of appropriate width for that particular image. Images have been produced by dividing the "counts" image by an exposure map.
  
  The first three sets are for the "total", "soft", and "hard" energy bands. The next 3 are for the three bands used to make the true-color image. Other images are in narrow bands selected to illustrate the spectral morphology of that particular remnant and differ from remnant to remnant.
  
  Any image can be downloaded in GIF, PS, or FITS format.
  
  
• True-color image: The true-color image and the 3 energy bands used are displayed. All have been smoothed with an adaptive smoothing algorithm (CSMOOTH). This smoothing sometimes produces different results than the gaussian smoothing displayed in the previous section. Reality of features can be evaluated by referring to the gaussian-smoothed and the "raw" images.
  
  
• Equivalent width map: This section shows narrow-band line images, a continuum image, and the equivalent width = line flux/average continuum flux map.
  
  
• Chandra Spectra: Spectrum of each region: Shows pi-bin spectra of each remnant and of various parts. Each region is outlined on an accompanying image and excluded regions are indicated with an outline and red slash. Each spectrum is compared to the spectrum of the entire remnant.
  
  
• Other Wavelengths:
  • Radio Images: A radio image is displayed on the same scale as the gaussian-smoothed X-ray image. Contours of constant radio surface brightness have been overlaid on the X-ray image. The radio image may be downloaded.
  
  
• Survey Missions: Depending on the remnant; shows IR, visual and radio images. The Chandra image is shown with the border outlined. Each survey image is shown on the same scale and on a reduced scale with the same outline. The purpose of the reduced scale image is to show the environment nearby.
  
  
• Nearby Sources: Unresolved (almost all serendipitous) obvious sources within a few arcminutes of the remnant. Locations are from the Chandra standard processing and existence of the sources has been verified by inspection of the image.
  
  
• References: for distance and to papers concerning these Chandra data.