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README File Version 1.0
August 23, 2001
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This is a brief README file for the images: 

  paper05-figure3-fullband-ascagrades-binned1pix-975ks.fits
  paper05-figure3-softband-ascagrades-binned1pix-975ks.fits
  paper05-figure3-hardband-ascagrades-binned1pix-975ks.fits
  paper05-figure3-ultrahardband-ascagrades-binned1pix-975ks.fits

associated with the paper:

 `The Chandra Deep Field North survey. V. 1 Ms source catalogs', 
 Brandt W.N., Alexander D.M., Hornschemeier A.E., Garmire G.P., 
 Schneider D.P., Barger A.J., Bauer F.E., Broos P.S., Cowie L.L., 
 Townsley L.K., Burrows D.N., Chartas G., Feigelson E.D., Griffiths R.E., 
 Nousek J.A., Sargent W.L.W., 2001, The Astronomical Journal, 122, 2810

and the WWW page: 

 http://www.astro.psu.edu/users/niel/hdf/hdf-chandra.html

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IMPORTANT NOTES

 * These images are the ones shown in Figure 3 of the paper cited above with 
   one exception: they are binned by a factor of one pixel (rather than four
   pixels) in both right ascension and declination. Please refer to the paper 
   for further details about them. 

 * Note that the raw data used to create these images are available from the
   Chandra X-ray Center. The methods we have used to convert the raw data
   into these images are described in the paper cited above. 

 * The astrometry in these images is good. However, it does not precisely 
   match the astrometry in the paper cited above (for example, see Table 3
   of the paper). After finding source positions using these images, we have
   performed further, small (at about the 0.2 arcsecond level on average) 
   astrometric improvements using an algorithm that solves for the best 
   possible shift, rotation, and plate-scale (see Section 3.1 of the paper). 
   Clearly, the astrometry described in the paper supersedes that in these 
   images. 

 * These images are provided on a "good-faith, best-effort, at-your-own-risk" 
   basis. 

 * We expect that Chandra data analysis methods will continue to improve in 
   the future. Thus, these images should not be taken to be the final data 
   products from this project. They should instead be taken to be products 
   from a good, but still improving, data analysis effort. 

 * Note that we are working on several scientific projects using these data;
   these efforts are quite advanced. If, before starting a project using
   these images, you would like to contact us to ask about possible conflicts, 
   this would be appreciated. 
 
 * If you find these images useful for your scientific work, we would be 
   grateful if you would cite the paper above.
 
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Niel Brandt; Department of Astronomy and Astrophysics; The Pennsylvania 
State University; 525 Davey Lab; University Park, PA 16802 USA
Phone: (814) 865-3509; FAX: (814) 863-3399; Office room number: 507
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