Ruprecht 20

Number of stars per data source

	Reference   67 :    1 star
	Reference  464 :    1 star

References

 67

Vogt N., Moffat A.F.J.

(1971) Astron. Astrophys. Suppl. 7, 133

Southern open star clusters I. UBV Hbeta photometry of 15 clusters between galactic longitudes 231 and 256

1971A&AS....7..133V

 464

Perry C.L.

(1991) publ. Astron. Soc. Pacific 103, 494

Interstellar reddening in the southern hemisphere. I. The uvby Beta observations

1991PASP..103..494P