The Chandra X-ray Observatory Data Archive provides a reference survey
via the HiPS protocol.
For detailed information on the Chandra Observatory and datasets see:
http://cxc.harvard.edu/ for general Chandra information;
http://cxc.harvard.edu/cda/ for the Chandra Data Archive;
http://cxc.harvard.edu/csc/ for Chandra Source Catalog information.
The Chandra X-ray Observatory is the U.S. follow-on to the Einstein
Observatory. Chandra was formerly known as AXAF, the Advanced X-ray
Astrophysics Facility, but renamed by NASA in December, 1998.
Originally three instruments and a high-resolution mirror carried in
one spacecraft, the project was reworked in 1992 and 1993. The Chandra
spacecraft carries a high resolution mirror, two imaging detectors,
and two sets of transmission gratings. Important Chandra features are:
an order of magnitude improvement in spatial resolution, good
sensitivity from 0.1 to 10 keV, and the capability for high spectral
resolution observations over most of this range.
The NASA/IPAC Extragalactic Database (NED) provides a comprehensive fusion
of multi-wavelength data for hundreds of millions of objects located beyond
the Milky Way galaxy. As new observations are published in NASA mission
archives, journal articles and sky survey catalogs, they are cross-identified
with prior measurements and integrated in a unified database. Numerous derived
quantities are also provided to facilitate scientific research. For more
information see http://ned.ipac.caltech.edu/