SIMBAD references

The absence or presence of extremely wide binaries with a radio pulsar and an optical counterpart imposes a strong constraint on the existence and magnitude of kicks in supernova explosions. We search for such systems by comparing the positions of radio pulsars which are not known to be in binaries with the positions of visible stars, and find that the number of associations is negligible. According to the performed population synthesis, this implies that kicks must occur, with a lower limit of at least 10 to 20km/s. The single 13-th magnitude star at a distance of 4.9 seconds of arc from the pulsar PSR B1929+10 is a good candidate to be the member of such a wide pair. If it turns out that this pulsar is indeed the member of a wide binary or if another wide pair will be found in the future, the kick-velocity distribution must have a significant contribution from low-velocity kicks.