Dr. Mahtab Gholami (INAF-OACn)
25 March 2026
11:30, Aula Piazzi
Abstract:
As the Vera C. Rubin Observatory begins full-scale operations, the need for high-cadence, multi-band benchmarks in crowded fields is critical. We present the results of a decadal photometric survey of the Galactic Bulge using the Dark Energy Camera (DECam), providing a strategic bridge between Saha’s historical datasets and future LSST Science. Our study leverages a massive ugriz archive spanning over 10 years, with individual light curves sampled up to 1,000 epochs, achieving a photometric depth equivalent to a single LSST visit. Focusing on the B2 field, we implemented a rigorous selection pipeline using the Stetson variability index and Generalized Lomb-Scargle (GLS) periodograms. By cross-matching with OGLE-IV, we demonstrate an 83% recovery rate of known variables after applying quality cuts (nmeas ≥15), with 96% of these yielding high-precision periods. A systematic manual vetting of all 61 DECam CCDs resulted in a final catalog of 7,950 high-quality variable candidates. A primary highlight of this work is the multi-band expansion of the OGLE-IV variables; while OGLE provides I and V photometry, our dataset adds u,g,r,i,z amplitudes and mean magnitudes. These data serve as a vital tracer for distance, reddening, and metallicity, providing a 5-filter “ground truth” for modeling Galactic stellar populations in the LSST era. This catalog offers an unprecedented look at pulsating variables in the Bulge, refining the period-luminosity-metallicity relations required for the next generation of Galactic structure studies.