Galactic structure studies with BATC star counts

We report the first results of star counts carried out with the National Astronomical Observatories (NAOC) 60/90 cm Schmidt Telescope in 15 intermediate-band filters from 3000 to 10000 Å in the BATC survey. We analyze a sample of over 1400 main sequence stars (\(14\le\)V\(\le21\)), which lie in the field with central coordinates R.A.=\(09^h53^m13^s.30\) and DEC=47\(^\circ49^{\prime}00^{\prime\prime}.0\) (J2000). The field of view is 0.95 deg\(^{2}\), and the spatial scale was \(1\arcsec.67\). In our model, the distribution of stars perpendicular to the plane of the Galaxy is given by two exponential disks (thin disk plus thick disk) and a de Vaucouleurs halo. Based on star counts, we derive the scale heights of the thin disk to be \(320^{+14}_{-15}\) pc and of the thick disk to be \(640^{+30}_{-32}\) pc, respectively, with a local density of \(7.0\pm1%\) of the thin disk. We find that the observed counts support an axial ratio of \(c/a\le0.6\) for a de Vaucouleurs \(r^{1/4}\) law, implying a more flattened halo. We also derive the stellar luminosity function (SLF) for the thin disk, and it partly agrees with the Hipparcos luminosity function.