# Cygnus X-1

> Galactic X-ray source in the constellation Cygnus that is very likely a black hole

**Wikidata**: [Q332674](https://www.wikidata.org/wiki/Q332674)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Cygnus_X-1)  
**Source**: https://4ort.xyz/entity/cygnus-x-1


## References

1. SIMBAD
2. The Galactic O-Star Spectroscopic Survey. I. Classification system and bright northern stars in the blue-violet at R ~ 2500
3. Freebase Data Dumps. 2013
4. Catalogue of Stellar Photometry in Johnson's 11-color system
5. Colors, magnitudes, spectral types and distances for stars in the field of the X-ray source Cyg X-1
6. Third U.S. Naval Observatory CCD Astrograph Catalog (UCAC3)
7. VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
8. Gaia Early Data Release 3
9. [Source](http://adsabs.harvard.edu/abs/1987ApJ...321..425N)
10. [Source](https://arxiv.org/abs/astro-ph/0501102)
11. [Source](http://www.cosmos-journal.ru/news/479/)
12. Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system
13. The IACOB project. III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars
14. [Source](https://hubble.esa.int/science-e/www/object/index.cfm?fobjectid=32700)
15. [Source](https://www.sciencemag.org/cgi/content/full/300/5622/1119)