# Puppis A

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**Puppis A** (**Pup A**) is a [supernova remnant](/source/Supernova_remnant) (SNR) about 100 [light-years](/source/Light-year) in diameter and roughly 6,500–7,000 light-years distant.[1] Its apparent angular diameter is about 1 degree.[2] The light of the supernova explosion reached Earth approximately 3,700 years ago. Although it overlaps the [Vela supernova remnant](/source/Vela_supernova_remnant), it is four times more distant.

A hypervelocity [neutron star](/source/Neutron_star) known as the [Cosmic Cannonball](/source/Cosmic_Cannonball) has been found in this SNR.

## Puppis X-1

Puppis X-1 (Puppis A) was discovered by a [Skylark](/source/Skylark_(rocket)) flight in October 1971, viewed for 1 minute with an accuracy ≥ 2 arcseconds,[3] probably at 1M 0821-426, with Puppis A ([RA](/source/Right_ascension) 08h 23m 08.16s [Dec](/source/Declination) -42° 41′ 41.40″) as the likely visual counterpart.

Puppis A is one of the brightest [X-ray sources in the X-ray sky](/source/Astrophysical_X-ray_source). Its X-ray designation is 2U 0821-42.

## References

1. ["Puppis A"](http://wise.ssl.berkeley.edu/gallery_Puppis_A.html). *WISE Multimedia Gallery*. NASA. 9 December 2011. Retrieved 21 November 2014.

1. Milne, D. K. (1971). "Radio observations of the supernova remnants IC443 and Puppis A". *Aust. J. Phys.*. **24**: 429. [Bibcode:1971AuJPh..24..429M](https://ui.adsabs.harvard.edu/abs/1971AuJPh..24..429M). [doi:10.1071/PH710429](https://doi.org/10.1071/PH710429)

1. Wiggin, M (December 2000). ["The Dome on Ball Hill – The RAE Observatory"](https://web.archive.org/web/20120227153520/http://www.astro.cardiff.ac.uk/sas/2000_02.pdf). Archived from [the original](http://www.astro.cardiff.ac.uk/sas/2000_02.pdf) on 2012-02-27.

## See also

- [List of supernova remnants](/source/List_of_supernova_remnants)

## External links

- Chandra: [Puppis A](https://chandra.harvard.edu/photo/2014/puppisa/index.html), date: 10 September 2014, retrieved 4 March 2025
- [Puppis A: Chandra Reveals Cloud Disrupted By Supernova Shock](https://chandra.harvard.edu/photo/2006/puppisa/), Chandra: NASA/CXC/GSFC/U. Hwang et al.; ROSAT: NASA/GSFC/S. Snowden et al.,
- [Simbad](http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=SNR+260.4-3.4&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id)

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Adapted from the Wikipedia article [Puppis A](https://en.wikipedia.org/wiki/Puppis_A) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Puppis_A?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.