研究目的
To investigate a huge sample of data related to the Stellar Abundance and Galactic Evolution (SAGE) survey in more detail by performing a northern sky photometric survey named SAGES with the SAGE photometric system to determine stellar atmospheric parameters for hundreds of millions of stars.
研究成果
The SAGE photometric system and survey are designed to produce high-quality photometry for about 500 million stars, enabling reliable measurements of atmospheric parameters. The pipeline achieves astrometric uncertainties of ～0.1 arcseconds and photometric depths meeting goals, but further improvements are needed for higher precision. SAGES will be a valuable resource for stellar physics and Galactic studies.
研究不足
The data reduction pipeline is not perfect, with issues like stripes in images that need removal. The photometric reference catalog for uSC and vSAGE filters is still being planned, and flux calibration accuracy needs improvement. The survey excludes certain sky areas due to telescope time allocation.
1：Experimental Design and Method Selection:
The SAGE photometric system is designed with eight filters to accurately determine stellar atmospheric parameters. The survey uses multiple telescopes for observations in different bandpasses, with a data reduction pipeline for image processing, astrometric calibration, and flux calibration.
2：Sample Selection and Data Sources:
The survey covers ～12,000 square degrees of the northern sky, excluding the Galactic disk and specific RA ranges. Data sources include observations from telescopes and reference catalogs like PPMX and PS
3：List of Experimental Equipment and Materials:
Telescopes include the Bok 90-inch telescope, Nanshan One-meter Wide-field Telescope (NOWT), and Zeiss-1000 Telescope at Maidanak Astronomical Observatory. Instruments include 90Prime camera and wide-field cameras with CCDs. Filters include Str?mgren-u, SAGE-v, SDSS g, r, i, DDO-51, Hαwide, and Hαnarrow.
4：Experimental Procedures and Operational Workflow:
Observations are conducted with specific exposure times for each filter. The pipeline performs overscan correction, bias subtraction, flat-fielding, crosstalk removal, astrometric calibration using SCAMP, source detection with SExtractor, aperture photometry, and flux calibration.
5：Data Analysis Methods:
Data analysis involves comparing astrometric and photometric results with reference catalogs, using software like SCAMP and SExtractor, and evaluating uncertainties through internal and external comparisons.
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