The BeppoSAX spacecraft, an Italian-Dutch spacecraft launched in 1996, located a gamma-ray burster in 1997 by matching its relatively high resolution in gamma rays with an even higher resolution x-ray observation. Optical telescopes on the ground as well as the Hubble Space Telescope were then able to detect the optical counterpart. Since it took over a month to fade out of view, some tremendous explosion seems to be involved. A model possibly favored is that of a collision of two neutron stars in some distant galaxy, with the fireball lighting up a huge interstellar region.
A series of measurements of Geminga with the Wide Field and Planetary Camera 2 on the Hubble Space Telescope has enabled its parallax to be measured. The parallax translates into a distance to this neutron star of 157 parsecs (+59, -34) = 512 light years, farther than had been thought but still very close on a celestial scale. Its proper motion was also measured, giving a transverse velocity of 122 km/s. The neutron star may have been formed in the same supernova explosion that caused the Local Bubble.
[References: P. A. Caraveo, G. F. Bignami, R. Mignani, and L. G. Taff, Astrophysical Journal, February 1996; G. F. Bignami and P. A. Caraveo, Annual Reviews of Astronomy and Astrophysics, 1996]