NGC 2539

Number of stars per data source

	Reference   25 :   36 stars
	Reference   38 :    3 stars
	Reference   50 :    3 stars

25: Zug R.S.; (1933) Lick Obs. Bull. 16, 119; An investigation of color excess in galactic star clusters
38: Pesch P.; (1961) Astrophys. J. 134, 602; Photometric and objective prism observations in three galactic clusters; 1961ApJ...134..602P
50: Cannon A.J., Pickering E.C.; (1918-1924), Ann. Obs. Harvard Coll. Obs. 91 to 99 and 100; Henry Draper catalogue and extension