# NGC 21

> spiral galaxy in the constellation Andromeda

**Wikidata**: [Q34500](https://www.wikidata.org/wiki/Q34500)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/NGC_21)  
**Source**: https://4ort.xyz/entity/ngc-21


## References

1. VizieR
2. SIMBAD
3. [NASA/IPAC Extragalactic Database](http://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=NGC%2021)
4. [Lyon-Meudon Extragalactic Database](http://leda.univ-lyon1.fr/ledacat.cgi?NGC%2021)
5. Freebase Data Dumps. 2013
6. Comparison LEDA/SIMBAD octobre 2002. Catalogue to be published in 2003
7. The Updated Zwicky Catalog (UZC)
8. The Two Micron All Sky Survey (2MASS)
9. Cosmicflows-3