The Stellar Abundances and Galactic Evolution Survey (SAGES). I. General Description and the First Data Release (DR1)

Abstract

The Stellar Abundances and Galactic Evolution Survey (SAGES) of the northern sky is a specifically designed multiband photometric survey aiming to provide reliable stellar parameters with accuracy comparable to those from low-resolution optical spectra. It was carried out with the 2.3 m Bok telescope of Steward Observatory and three other telescopes. The observations in the u s and v s passband produced over 36,092 frames of images in total, covering a sky area of ∼9960 deg2. The median survey completenesses of all observing fields for the two bands are u s = 20.4 mag and v s = 20.3 mag, respectively, while the limiting magnitudes with signal-to-noise ratio of 100 are u s ∼ 17 mag and v s ∼ 18 mag, correspondingly. We combined our catalog with the data release 1 (DR1) of the first Panoramic Survey Telescope And Rapid Response System (Pan-STARRS, PS1) catalog, and obtained a total of 48,553,987 sources that have at least one photometric measurement in each of the SAGES u s and v s and PS1 grizy passbands. This is the DR1 of SAGES, released in this paper. We compared our gri point-source photometry with those of PS1 and found an rms scatter of ∼2% difference between PS1 and SAGES for the same band. We estimated an internal photometric precision of SAGES to be of the order of ∼1%. Astrometric precision is better than 0.″2 based on comparison with DR1 of the Gaia mission. In this paper, we also describe the final end-user database, and provide some science applications.

Beyond Spectroscopy. II. Stellar Parameters for over 20 Million Stars in the Northern Sky from SAGES DR1 and Gaia DR3

“…In the present work, the SAGES DR1 (Fan et al 2023) data set is adopted. SAGES DR1 has released a total of about 100 million sources extracted from 36,092 accepted frames in the uv bands collected by the 90 inch (2.3 m) Bok Telescope at Kitt Peak National Observatory in Arizona.…”

“…In the final sample, over 22 million dwarf and 3 million giant stars have photometric-metallicity estimates (see Section 3) from the stellar colors provided by SAGES DR1 (Fan et al 2023) A description of the information for stars in the final sample catalog is presented in Table 3. The final stellar-parameter sample catalog will be released by the SAGES project as a value added catalog.…”

“…In this paper, we present a second pioneering experiment in the Northern sky, using the data from the first data release of the Stellar Abundance and Galactic Evolution Survey Data Release 1 (SAGES DR1; Fan et al 2023) and Gaia Early Data Release 3 (EDR3; Gaia Collaboration et al 2021). SAGES is an optical multiband (u, v, g, r, i, DDO − 51, Hα wide , Hα narrow ) large-scale photometric survey, aiming to cover 12,000 deg 2 of the Northern sky with δ > − 5°down to a 5σ depth of 21.5 in the u band (Zheng et al 2018).…”

Filter Design for Estimation of Stellar Metallicity: Insights from Experiments with Gaia XP Spectra

“…In addition to this system, Bessell et al (2011) designed the SkyMapper filter set by inserting a v-band filter between the Sloan Digital Sky Survey (SDSS)-like u-and g bands to obtain high-sensitivity to metallicity, and a Strömgren-like u band to provide sensitivity to both temperature (for hot stars) and surface gravity (for A/F/G/K-type stars). This system has been adopted by the SkyMapper Southern Survey (SkyMapper; Wolf et al 2018) and the Stellar Abundances and Galactic Evolution Survey (SAGES; Fan et al 2023), yielding stellarparameter estimates for about 50 million stars covering almost 3π steradians of sky (Huang et al 2022(Huang et al , 2023. To minimize the influence of molecular bands from carbon and nitrogen, the Pristine survey (Starkenburg et al 2017) has proposed a narrower filter specifically centered on the wavelengths of the Ca II H&K doublet lines, hereafter referred to as the Ca HK band.…”