Abstract:
The SAGE survey adopts a unique photometric system, which consists of Stromgren-Crawford (SC) intermediate-band u, self-designed v_SAGE, gri, Hα_n/Hα_w and DDO51. The system is proved to be powerful and sensitive for the study of atmospheric parameters of various types of stars. The parameters, like effective temperature, gravity, and metallicity, yielded from our SAGE system are more accurate than those from the traditional broad-band photometric system or low-resolution spectra. It is also useful for the determination of extinction, stellar distance, radius, and stellar evolutionary phases. In this case, we propose a northern deep sky survey in the self-designed SAGE system with Steward Bok 90-inch (2.3m) telescope, Nanshan 1-m wide-field telescope of Xinjiang Astronomical Observatories, the Maidanak 1-m telescope of Uzbekistan, and the Xuyi 1-m Schmidt telescope. To date, the observations for u/v band have almost done; for g/r/i bands the observations also are done. For the Hα_n/Hα_w bands and DDO51 bands, the observations will be carried out very soon. The limiting mag is ~20 mag (S/N=5) in u/v-band, and the stellar parameters of >0.5 billion stars have been derived. The SAGE survey will not only provide an accurate input catalog for the LAMOST survey but also provide the big data for the formation and evolution of the Milky Way, especially combined with the spatial and velocity information from LAMOST and the Gaia data.
