NGC 2506

Number of stars per data source

	Reference  220 :  704 stars
	Reference  284 :  587 stars

220: Choi H.S., Kim S.-L., Kang Y.H., Park B.-G.; (1999) Astron. Astrophys. 348, 789; Search for variable stars in the open cluster NGC 7654; 1999A&A...348..789C
284: Kim S.L., Chun M.-Y., Park B.-G., Kim S.C., Lee S.-H., Lee M.G., Ann H.B., Sung H., Jeon Y.-B., Yuk I.-S.; (2001) Acta Astron. 51, 49; Search for variable stars in two old open clusters: NGC 2506 and NGC 2420; 2001AcA....51...49K