ïùñîþÿøîîøîòóúö ûîûîøöó · 50 t min 20 30 Fig. 4. Dependence between the B magnitude of the faintest star which conf ident photometric measurements could be
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БЛГАРСКА АКАДЕМИ НА НАКИЕ • BULGARIAN ACADEMY OF SCIENCES АСРОИЗИЕСКИ ИЗСЛЕДВАНИ, 7 • ASTROPHYSICAL INVESTIGATIONS, 7 С • 1996 • Sofia __________________ 198