Rubin-LSST will provide an unprecedented combination of time coverage, 6-bands photometric depth and spatial extension for a variety of environments. In particular, crowded stellar fields (the Galactic Plane and Bulge, Galactic Globular Clusters, the Magellanic Clouds) will be of particular interest for a relevant part of the Community that investigate a series of astrophysical topics, spanning from the physics of variable stars to Galactic structure and near-field cosmology. A key role will be played by periodic variable stars (intrinsic, such as RR Lyrae stars, Anomalous and Classical Cepheids, Delta Scuti stars, Miras, but also eclipsing binaries), which have traditionally been used as population tracers and standard candles. For these reasons, it is essential to have access to efficient tools, capable of providing reliable identification, classification, and recovering the period, amplitude and mean magnitudes of candidate variable stars.

We therefore propose to adapt and test current state-of-the-art analysis tools, to work with the simulated DP0 data, and with Galactic Plane and Bulge DECam data. Our deliverables will be a python package to interface the Rubin-LSST data with selected analysis software (which can eventually be made available on the Science Platform), and a report with the performance of the selected software on both the DP0 and the DECam data.

We will complete our analysis on the DECam data around the Bulge Globular Cluster NGC 6569, which has been extensively used as a benchmark for the TVS crowded stellar fields Task Force since 2018. We will deliver a science paper, which will be published according to the TVS publication policy.

Finally, we will produce a novel analysis of variable stars in a DECam disc field close to the Galactic plane, using deep data that will allow us to test the variability algorithms with different stellar populations and crowding conditions.