Puppis A (Pup A) is a supernova remnant (SNR) about 100 light-years in diameter and roughly 6500âÂÂ7000 light-years distant. Its apparent angular diameter is about 1 degree. The light of the supernova explosion reached Earth approximately 3700 years ago. Although it overlaps the Vela Supernova Remnant, it is four times more distant.
A hypervelocity neutron star known as the Cosmic Cannonball has been found in this SNR.
Puppis X-1 (Puppis A) was discovered by a Skylark flight in October 1971, viewed for 1 min with an accuracy âÂÂ¥ 2 arcsec, probably at 1M 0821-426, with Puppis A (RA 08<sup>h</sup> 23<sup>m</sup> 08.16<sup>s</sup> Dec -42ð 41â² 41.40â³) as the likely visual counterpart.
Puppis A is one of the brightest X-ray sources in the X-ray sky. Its X-ray designation is 2U 0821-42.