Here is a basic comparison of AXAF and its principal predecessors.
| Property | AXAF | RoSat | Einstein |
| Focal length (m) | 10.00 | 2.40 | 3.45 |
| Diameters (cm) | 63 to 20 | 51-83 | 33-58 |
| Collecting area (sq-cm) | 780 | 350 | 200 |
| Coating | Iridium | Gold | Nickel |
| Size of Crab Nebula image (mm) | 8.0 | 1.9 | 2.7 |
| Resolution (arc-sec) | 0.5 | 3.0 | 4.0 |
The Crab Nebula, one of the most famous objects in all disciplines of astronomy, is the remnant of a star whose explosion was first seen here in the year 1054 CE. It is a shell of gas expanding from a pulsar that can be seen in radio, visible, and X-ray wavelengths.
Go back to the AXAF mirror story, or return to AXAF main story.
Updated Feb. 4, 1997
Authors: Dave Dooling
Curator: Bryan Walls
NASA Official: John M. Horack