A map of X-ray sources, shown in galactic co-ordinates, showing that our galaxy contains many sources.

Two of the X-ray sources provided an important discovery about the nature of some of the galactic sources found by Uhuru. Cen X-3, the third source found in the Centaurus region, was found to be pulsating with a period of 4.8 seconds. The other, Her X-1, the first source found in the Hercules region, was also found to be pulsating, this time with a period of 1.24 seconds.

These pulsations, along with regular "blackouts", were interpreted as the effects of the rotation of a neutron star around another star - a binary star system!

Another important discovery was that some of the "high-latitude" sources (those not along the plane of our galaxy, as shown in the diagram above) were associated with glusters of galaxies. For example, one source was previously identified optically as the M87 galaxy.

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