NGC 581

Number of stars per data source

	Reference    1 :    4 stars
	Reference    4 :   19 stars
	Reference   15 :  119 stars
	Reference  150 :   69 stars
	Reference  264 :  204 stars

1: Egret D.; (1986) Private Communication; Coordinates from SIMBAD (mainly SAO)
4: Hoag A.A., Johnson H.L., Iriarte B., Mitchell R.I., Hallam K.L., Sharpless S.; (1961) Publ. Us. Nav. Obs. XVII part VII, 347; Photometry of stars in galactic cluster fields
15: Moffat A.F.J., Vogt N.; (1974) Veroeff. Astr. Inst. Univ. Bochum no 2; Photographische UBV-Helligkeiten in 14 jungen Sternhaufen der nordlichen Milchstrasse
150: Evstigneeva K.M., Shokin Yu.A., Yuferev A.O.; (1991) Trudy Gos. Astr. Inst. Shternberga 62, 234; Precise positions of reference stars in opn clusters NGC 457 and NGC 581
264: Sanner J., Geffert M., Brunzendorf J., Schmoll J.; (1999) Astron. Astrophys. 349, 448; Photometric and kinematic studies of open star clusters. I. NGC 581 (M 103); 1999A&A...349..448S