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Rubin LSST-France, LPSC Grenoble, 24-26/11/2025

24–26 nov. 2025
Laboratoire de Physique Subatomique et de Cosmologie Amphithéâtre
Fuseau horaire Europe/Paris

Liste des Contributions

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  1. 3. Introduction
    Benjamin Racine (CPPM/IN2P3/CNRS)
    24/11/2025 14:00
  2. 4. News from Rubin and DESC + communication
    Dr Johan Bregeon (IN2P3 LSPC)
    24/11/2025 14:10
  3. 5. EDI
    24/11/2025 14:50
  4. 6. Computing + update CC
    Dominique Boutigny (LAPP), Fabio Hernandez (CC-IN2P3)
    24/11/2025 15:05
  5. 7. lightning DP1/DP2?
    24/11/2025 15:35
  6. 9. Invited talk: retrospective on the filter loader
    Francis VEZZU (LPSC)
    24/11/2025 16:50
  7. 27. The Rubin ToO Program
    Sean MacBride (University of Zurich)
    24/11/2025 17:25

    Rubin Observatory is a discovery machine, with the capability to identify exotic astrophysical transients faster than any existing observatory. 3% of the LSST has been allocated for Target of Opportunity observations, which includes an observatory response to gravitational wave events, high energy neutrinos, potentially-hazardous asteroids, and other astrophysical phenomena. Target of...

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  8. 10. Introduction on what we do in a 3x2pt cosmological analysis
    Cyrille Doux (LPSC)
    24/11/2025 18:00
  9. 11. Introduction to DESC tools
    eduardo barroso (LAPP)
    25/11/2025 09:00
  10. 8. Introduction to Calibration and Instrument Signal Removal
    Thibault Guillemin (LAPP)
    25/11/2025 09:30
  11. 26. StarDICE IV: a new hope
    Marc Betoule (LPNHE)
    25/11/2025 10:10

    StarDICE is a photometric calibration experiment attempting to
    establish NIST-traceable spectrophotometric standard stars for the
    upcoming LSST supernova survey. Since the last LSST-France meeting,
    the experiment has resumed observations after upgrades in the data
    acquisition, and a thorough measurement campain of the instrument
    transmission curves using a dedicated instrument called...

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  12. 17. Toward 1 mmag Photometric Precision in Y band : PWV Measurement Challenges and Advances
    Dr Sylvie Dagoret (IJCLab)
    25/11/2025 11:00

    Accurate modeling of precipitable water vapor (PWV) variations is essential to meet Rubin Observatory’s photometric precision requirements, particularly in the Y band. Simulations with getObsAtmo and rubin_sim show that achieving photometric errors below 1, 5, and 10 mmag corresponds respectively to statistical PWV uncertainties of ΔPWVₛₜₐₜ < 0.03, 0.1, and 0.5 mm.
    PWV measurements...

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  13. 28. New AuxTel standards with Gaia
    Corentin Ravoux (LPC Clermont-Ferrand CNRS/IN2P3)
    25/11/2025 11:20

    The Auxiliary telescope (AuxTel) of the Rubin Observatory is a spectrometer that precisely characterizes the atmosphere during LSST observation. Observing standard stars and comparing the resulting spectra with out-of-atmosphere CALSPEC spectra gives the whole atmospheric transmission curve. This procedure is performed with a forward modeling software called Spectractor, which is implemented...

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  14. 32. Retour d'expérience avec les CBP
    Jérémy Neveu (IJCLab)
    25/11/2025 11:40

    Je propose une présentation pour la session parallèle CBP. Je parlerai des différentes versions du CBP qui ont été construites parallèlement à celui de Rubin, pour mettre en lumière leurs résultats, leurs avantages et inconvénients, ainsi que les leçons apprises qui font écho aux travaux sur le CBP Rubin.

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  15. 36. Other contributions to CBP // session
    25/11/2025 12:00
  16. 29. $f\sigma_8$ measurement with the type Ia Supernovae from the Zwicky Transient Facility DR2.5
    Rafael Kebadian (CPPM)
    25/11/2025 14:00

    $f\sigma_8$ is a powerful probe at low redshift to discriminate between different theories of gravity. In linear theory, this parameter is directly related to the velocity field. In this talk, I will show how the peculiar velocities of ZTF Type Ia supernovae can be used to measure $f\sigma_8$ . I apply a maximum likelihood approach together with realistic simulations based on N-body mocks. I...

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  17. 19. Cosmology with peculiar velocities from LSST supernovae
    Damiano Rosselli (CPPM)
    25/11/2025 14:20

    We present the first forecast for the measurement of the cosmic growth-rate parameter, fσ8, using peculiar velocities (PVs) derived from Type Ia supernovae (SNe Ia) in the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST). We produce simulations of different SNe types using a realistic LSST observing strategy, incorporating noise, photometric detection from the Difference...

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  18. 22. skysurvey : a Python library for fast, easy, and realistic transient simulations for LSST-like surveys
    Luna Dellazzeri (Institut de Physique des 2 Infinis de Lyon)
    25/11/2025 14:40

    Realistic transient simulations are essential to interpret the observations of surveys such as LSST.
    I will present skysurvey, a Python library developed in the cosmological team in Lyon, that simulates astrophysical transients, and in particular Type Ia supernovae, for any survey, including LSST. skysurvey aims to combine computational efficiency, ease of use, and physical realism and...

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  19. 20. Simulation-Based Inference (SBI) for cosmology with type Ia Supernovae (SNe Ia).
    Adam Trigui (IP2I)
    25/11/2025 15:00

    Systematic uncertainties associated to calibration, selection function and astrophysical effects are dominating the error budget of SN Ia cosmology. Correction methods applied to account for these systematics, and especially for the complex combination of selection function and astrophysical variability, are questionable, particularly given the current H0 and Lambda tensions for which SN Ia...

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  20. 18. Halo Mass Function closure tests
    Narei Lorenzo Martinez (LAPP)
    25/11/2025 15:20

    The Halo Mass Function (HMF) is a parametric function that allows to describe the distribution of halos masses given a cosmology and the redshift. It is thus widely used in cluster analyses to extract cosmological parameters like sigma_8 and Omega_M from the observation of clusters. Many different HMF exist in the literature with different parameterizations as a function of redshift and...

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  21. 1. Simulation-based cosmological inference from optically-selected galaxy clusters
    Constantin Payerne (CEA/DPhP/Irfu)
    25/11/2025 15:40

    Galaxy clusters are among the most powerful probes of cosmology, providing key insights into the growth of structure and the nature of dark energy. However, translating cluster observations into robust cosmological constraints remains challenging, primarily due to uncertainties in mass calibration and systematic effects. Upcoming surveys such as the Rubin Observatory’s LSST and Euclid will...

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  22. 14. Discussions on AI
    25/11/2025 16:30
  23. 37. Centre Pierre Binétruy
    Prof. James Bartlett (Centre Pierre Binétruy)
    25/11/2025 17:35

    I will present the Centre Pierre Binétruy, located on the campus at UC Berkeley and working closely with Stanford and SLAC. The Center's role is to facilitate collaborations between French researchers and researchers in the Bay Area: UC Berkeley, LBNL, Stanford, SLAC. We have funds to support travel and can host short- and long-term visitors. One of our flagship projects is Rubin/LSST.

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  24. 13. Fink broker Status Update
    Dr Emille Ishida (CNRS/LPC-Clermont)
    26/11/2025 09:00

    I will give an overview of the last activities of the Fink broker, and describe the status of processing Rubin alerts.

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  25. 12. Early Inference of Supernova Light Curve Parameters with Physics-Informed Neural Networks
    Gabriel Teixeira (Centro Brasileiro de Pesquisas Físicas)
    26/11/2025 09:20

    The early light curves of supernovae provide critical insights into the properties of their progenitor systems and, in some cases, play an essential role in our understanding of the evolution of the Universe. With the advent of wide-field surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), large samples of early supernova light curves will become available,...

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  26. 31. Vetting Fast transients with LSST : preparatory work with ZTF
    Alex Jacquesson (IJCLab pôle a2c og)
    26/11/2025 09:40

    The LSST will provide an excellent opportunity to study a wide range of fast transients and to better understand the diverse physical mechanisms driving explosive astrophysical events. During the first month of my PhD, I conducted research aimed at distinguishing rapid explosive transients and performed systematic scans using the Skyportal platform and the private ZTF alert stream. These same...

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  27. 30. Study the blazar variability through ZTF/LSST and the CTAO with Fink
    Julian Hamo (IJCLab)
    26/11/2025 10:00

    To date, blazars constitute the largest population of objects in the extragalactic gamma-ray sky. They generate over 50% of the extragalactic diffuse gamma-ray background photon flux at energies higher than 100 MeV. They are a subclass of active galactic nuclei that exhibit a relativistic jet pointing towards Earth at an angle of less than 10°. Their electromagnetic emission spans from radio...

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  28. 21. Early identification of Optical Tidal Disruption Events: A science module for the Fink broker
    Dr Miguel Llamas Lanza (IRAP)
    26/11/2025 10:20

    Tidal disruption events (TDEs) refer to the destruction of a star by the tidal forces around a black hole, leading to outbursts that can last for months. Although modern optical time-domain surveys have substantially expanded the known TDE sample, these events remain rare. Further increasing the sample is crucial for advancing our understanding of the underlying physics, making TDE discovery a...

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  29. 23. The cosmic matter dipole problem and weak lensing
    Albert Bonnefous (Institut d'Astrophysique de Paris)
    26/11/2025 11:10

    The Ellis and Baldwin formula provides a model-independant way to measure our own velocity with respect to matter at large scale. However, this measurement doesn't coincide with the same measurement with respect to the CMB, which puts into question the existence of the Cosmological Rest Frame [Secrest et al. 2021]. I will explain how LSST will provide an extremely useful data set to work on...

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  30. 24. Full-Field Weak Lensing Inference at LSST Scale with Differentiable, Distributed Simulations
    Wassim KABALAN (CNRS APC/IN2P3)
    26/11/2025 11:30

    Weak gravitational lensing maps contain rich, non-Gaussian information that standard two-point statistics miss. Full-field inference tackles this by forward-modeling the entire map—evolving initial conditions through structure formation and observational effects—and using the maps themselves to learn about cosmology, without compressing to summary statistics.

    In this talk, I will...

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  31. 25. Probabilistic Inference of Galaxy Properties from Multi-Modal Latent Space Representations
    Kirill Grishin (Astroparticle and Cosmology Lab., CNRS)
    26/11/2025 11:50

    Cosmological research in the era of deep, wide-area surveys such as Euclid and Rubin/LSST benefits greatly from combining datasets collected with different instruments. However, the large volume of data makes analysis increasingly challenging. To address this, we developed a package based on the Variational Autoencoder (VAE) architecture that enables compact representations of spectroscopic...

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  32. 35. Estimating Rubin/LSST sensitivity to dark matter subhalos impact on stellar streams
    Matthieu Pelissier (LPSC/UGA)
    26/11/2025 12:10

    Dark matter subhalos with masses from 10⁶ to 10⁹ solar masses are mostly invisible, but could impact the structure of stellar streams observed by LSST. Presentation on how LSST systematics could impact density fluctuations measurements in stellar streams, used to set dark matter constrains.

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  33. 34. Cosmology from the Rubin Void Size Function
    Pierre Boccard (CPPM)
    26/11/2025 12:30

    Cosmic voids are a powerful tool to extract cosmological constraints and study galaxy properties’ dependence on the environment. This project builds a pipeline for constraining cosmological parameters using the void size function (VSF). We build the void catalogs from the SkySim5000 galaxy catalogs using the publicly available VIDE void finder. The cosmological constraints’ inference relies...

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  34. 38. Last words
    Dr Johan Bregeon (IN2P3 LSPC)
    26/11/2025 12:50
  35. 16. Computing environment for Rubin science analysis at IN2P3
    Dominique Boutigny (LAPP)

    I will present the plans to deploy the computing infrastructure in support of Rubin science at IN2P3. I will also describe the tests that we intend to perform on the short term to validate and improve the model.

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  36. 33. Estimating Rubin/LSST sensitivity to dark matter subhalos impact on stellar streams
    Matthieu Pelissier (LPSC/UGA)

    Dark matter subhalos with masses from 10⁶ to 10⁹ solar masses are mostly invisible, but could impact the structure of stellar streams observed by LSST. Presentation on how LSST systematics could impact density fluctuations measurements in stellar streams, used to set dark matter constrains.

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  37. 2. Invited talk : Rubin TOO
    Sean MacBride (University of Zürich)