NGC 2506

Number of stars per data source

	Reference   71 :  309 stars
	Reference  113 :    2 stars
	Reference  128 :   14 stars
	Reference  220 :  863 stars

71: Mermilliod J.-C.; (1988); Positions measured with the Hipad tablet
113: Lasker B.M., et al; (1988) Astrophys. J. Suppl. 68, 1; The Guide Star Photometric Catalog. I.; 1988ApJS...68....1L
128: Lasker B.M., Russel J.N., Jenkner H., Sturch C.R., McLean B.J., Shara M.M.; (1990) Astron. J. 99, 2019; The HST guide star catalogue, version 1.0; 1990AJ.....99.2019L
220: Marconi G., Hamilton D., Tosi M., Bragaglia A.; (1997) Mon. Not. R. Astron. Soc. 291, 763; Old open clusters: UBGVRI photometry of NGC 2506; 1997MNRAS.291..763M