# HAT-P-21

> star in the constellation Ursa Major

**Wikidata**: [Q4039803](https://www.wikidata.org/wiki/Q4039803)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/HAT-P-21)  
**Source**: https://4ort.xyz/entity/hat-p-21


## References

1. SIMBAD
2. Source
3. The Tycho-2 catalogue of the 2.5 million brightest stars
4. Third U.S. Naval Observatory CCD Astrograph Catalog (UCAC3)
5. VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
6. Gaia Early Data Release 3
7. HAT-P-20b-HAT-P-23b: four massive transiting extrasolar planets
8. Gaia Data Release 2
9. Improved spectroscopic parameters for transiting planet hosts