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Abstract We present an independent validation and comprehensive recalibration of S-PLUS Ultra-short Survey (USS) DR1 12-band photometry using about 30,000–70,000 standard stars from the Best Star (BEST) database. We identify the spatial variation of zero-point offsets, up to 30–40 mmag for blue filters (u,J0378, andJ0395) and 10 mmag for others, predominantly due to the higher uncertainties of the technique employed in the original USS calibration. Moreover, we detect large- and medium-scale CCD position-dependent systematic errors, up to 50 mmag, primarily caused by different aperture and flat-field corrections. We then recalibrate the USS DR1 photometry by correcting the systematic shifts for each tile using second-order two-dimensional polynomial fitting combined with a numerical stellar flat-field correction method. The recalibrated results from the XP spectrum based synthetic photometry and the stellar color regression standards are consistent within 6 mmag in the USS zero-points, demonstrating both the typical precision of the recalibrated USS photometry and a sixfold improvement in USS zero-point precision. Further validation using the Sloan Digital Sky Survey and Pan-STARRS1, as well as LAMOST DR10 and Gaia photometry, also confirms this precision for the recalibrated USS photometry. Our results clearly demonstrate the capability and efficiency of the BEST database in improving calibration precision to the millimagnitude level for wide-field photometric surveys. The recalibrated USS DR1 photometry is publicly available on ChinaVO at doi:10.12149/101503. 

Context. This paper presents the first public data release of the S-PLUS Ultra-Short Survey (USS), a photometric survey with short exposure times, covering approximately 9300 deg²of the Southern sky. The USS utilizes the Javalambre 12-band magnitude system, including narrow, medium, and broad-band filters targeting prominent stellar spectral features. The primary objective of the USS is to identify bright, extremely metal-poor (EMP; [Fe/H] ≤ −3) and ultra-metal-poor (UMP; [Fe/H] ≤ −4) stars for further analysis using medium- and high-resolution spectroscopy. Aims. This paper provides an overview of the survey observations, calibration method, data quality, and data products. Additionally, it presents the selection of EMP and UMP candidates. Methods. The data from the USS were reduced and calibrated using the same methods as presented in the S-PLUS DR2. An additional step was introduced, accounting for the offset between the observed magnitudes off the USS and the predicted magnitudes from the very low-resolution Gaia XP spectra. Results. This first release contains data for 163 observed fields totaling ~324 deg²along the Celestial Equator. The magnitudes obtained from the USS are well-calibrated, showing a difference of ~15 mmag compared to the predicted magnitudes by the GaiaXPy toolkit. By combining colors and magnitudes, 140 candidates for EMP or UMP have been identified for follow-up studies. Conclusions. The S-PLUS USS DR1 is an important milestone in the search for bright metal-poor stars, with magnitudes in the range 10 <r ≤14. The USS is an ongoing survey; in the near future, it will provide many more bright metal-poor candidate stars for spectroscopic follow-up.