Counts and Colours of Faint Stars in 5 Fields Near the North Galactic Pole

Abstract

Faint star number counts in the photographic \jmag band and \bvcol colour distributions are presented for a 1.08 deg$^2$ field near the North Galactic Pole. Due to the excellent star/galaxy discrimination we count stars as faint as \jmag = 23. We compare the number counts and colour distributions in 5 adjacent fields near SA57. The number counts and colour distributions are in very good agreement with previous data. However, we find that the large field-to-field scatter in the colour distributions, which we argue is real, might prevent us setting strong limits on Galactic structure. A simple two component standard model, Bahcall and Soneira (1984), fits the number counts reasonably well at the bright \jmag $< 21$, but fails notably at the faint end, even if a third component is added, as in Reid and Majewski (1993). The standard models are in good agreement with both the number counts and colour distribution at $20 < $\vmag$< 21$. Although the standard models bimodal shape of the colour distribution compares well with the data at $21 < $\vmag$< 21.5$, the number counts of stars are underestimated.