Puppis A is a supernova remnant (SNR) about 10 light-years in diameter. The supernova 'occurred' (ie. would have been seen on earth) approximately 3700 years ago. Although it overlaps the Vela Supernova Remnant, it is four times more distant.
Puppis X-1 (Puppis A) was discovered by a Skylark flight in October 1971, viewed for 1 min with an accuracy ≥ 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 -42º 41' 41.40") as the likely visual counterpart.