Name: Rubin LSST-France, LPSC Grenoble, 24-26/11/2025
Start: 2025-11-24T12:00:00+01:00
End: 2025-11-26T16:30:00+01:00
Location: Laboratoire de Physique Subatomique et de Cosmologie Amphithéâtre

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

de lundi 24 novembre 2025 (12:00) à mercredi 26 novembre 2025 (16:30)

lundi 24 novembre 2025
14:00 General updates: General updates
General updates
14:00 - 16:00
Room: Amphithéâtre
Contributions

14:00 Introduction - Benjamin Racine (CPPM/IN2P3/CNRS)

14:10 News from Rubin and DESC + communication - Johan Bregeon (IN2P3 LSPC)

14:50 EDI

15:05 Computing + update CC - Dominique Boutigny (LAPP) Fabio Hernandez (CC-IN2P3)

15:35 lightning DP1/DP2?
16:00 coffee break
coffee break
16:00 - 16:30
Room: Amphithéâtre

16:30 General updates: Lightning talks
Lightning talks
16:30 - 16:50
Room: Amphithéâtre
16:50 Invited talk: retrospective on the filter loader - Francis VEZZU (LPSC)
Invited talk: retrospective on the filter loader
- Francis VEZZU (LPSC)
16:50 - 17:25
Room: Amphithéâtre
17:25 The Rubin ToO Program - Sean MacBride (University of Zurich)
The Rubin ToO Program
- Sean MacBride (University of Zurich)
17:25 - 18:00
Room: Amphithéâtre 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 Opportunity observations exist outside of the usual LSST operational mode, and therefore require special attention to ensure maximum discovery capabilities. I will briefly review the community designed ToO observing strategies, integration activities during 2025, ToO's pursued since LSST first photon, and the Rubin-LVK-IceCube ToO mock data challenge.
18:00 Introduction on what we do in a 3x2pt cosmological analysis - Cyrille Doux (LPSC)
Introduction on what we do in a 3x2pt cosmological analysis
- Cyrille Doux (LPSC)
18:00 - 18:30
Room: Amphithéâtre
mardi 25 novembre 2025
09:00 Introduction to DESC tools - eduardo barroso (LAPP)
Introduction to DESC tools
- eduardo barroso (LAPP)
09:00 - 09:30
Room: Amphithéâtre
09:30 Science talks: Calibration
Calibration
09:30 - 10:30
Room: Amphithéâtre
Contributions

09:30 Introduction to Calibration and Instrument Signal Removal - Thibault Guillemin (LAPP)

10:10 StarDICE IV: a new hope - Marc Betoule (LPNHE)
10:30 coffee break
coffee break
10:30 - 11:00
Room: Amphithéâtre
11:00 Science talks: More Calibration
More Calibration
11:00 - 11:40
Room: Amphithéâtre
Contributions

11:00 Toward 1 mmag Photometric Precision in Y band : PWV Measurement Challenges and Advances - Sylvie Dagoret (IJCLab)

11:20 New AuxTel standards with Gaia - Corentin Ravoux (LPC Clermont-Ferrand CNRS/IN2P3)
11:40 Parallel: CBP
CBP
11:40 - 12:40
Room: Amphithéâtre
Contributions

11:40 Retour d'expérience avec les CBP - Jérémy Neveu (IJCLab)

12:00 Other contributions to CBP // session
Parallel: Clusters - informal discussion
Clusters - informal discussion
11:40 - 12:40
Room: Salle 345 (3ieme étage)

Parallel: Discussion on Stellar Streams
Discussion on Stellar Streams
11:40 - 12:40
Room: Grande Salle du Conseil

12:40 Lunch break
Lunch break
12:40 - 14:00
Room: Amphithéâtre
14:00 Science talks: Transients
Transients
14:00 - 15:20
Room: Amphithéâtre
Contributions

14:00 $f\sigma_8$ measurement with the type Ia Supernovae from the Zwicky Transient Facility DR2.5 - Rafael Kebadian (CPPM)

14:20 Cosmology with peculiar velocities from LSST supernovae - Damiano Rosselli (CPPM)

14:40 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)

15:00 Simulation-Based Inference (SBI) for cosmology with type Ia Supernovae (SNe Ia). - Adam Trigui (IP2I)
15:20 Science talks: Clusters
Clusters
15:20 - 16:00
Room: Amphithéâtre
Contributions

15:20 Halo Mass Function closure tests - Narei Lorenzo Martinez (LAPP)

15:40 Simulation-based cosmological inference from optically-selected galaxy clusters - Constantin Payerne (CEA/DPhP/Irfu)
16:00 Coffee break
Coffee break
16:00 - 16:30
Room: Amphithéâtre
16:30 Parallel: Discussion on AI
Discussion on AI
16:30 - 17:35
Room: Amphithéâtre
Contributions

16:30 Discussions on AI
17:35 Centre Pierre Binétruy - James Bartlett (Centre Pierre Binétruy)
Centre Pierre Binétruy
- James Bartlett (Centre Pierre Binétruy)
17:35 - 17:55
Room: Amphithéâtre 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.
19:00 Diner à Cosmo-Cité
Diner à Cosmo-Cité
19:00 - 22:00
Room: Amphithéâtre
mercredi 26 novembre 2025
09:00 Science talks: FINK
FINK
09:00 - 10:40
Room: Amphithéâtre
Contributions

09:00 Fink broker Status Update - Emille Ishida (CNRS/LPC-Clermont)

09:20 Early Inference of Supernova Light Curve Parameters with Physics-Informed Neural Networks - Gabriel Teixeira (Centro Brasileiro de Pesquisas Físicas)

09:40 Vetting Fast transients with LSST : preparatory work with ZTF - Alex Jacquesson (IJCLab pôle a2c og)

10:00 Study the blazar variability through ZTF/LSST and the CTAO with Fink - Julian Hamo (IJCLab)

10:20 Early identification of Optical Tidal Disruption Events: A science module for the Fink broker - Miguel Llamas Lanza (IRAP)
10:40 Coffee break
Coffee break
10:40 - 11:10
Room: Amphithéâtre
11:10 The cosmic matter dipole problem and weak lensing - Albert Bonnefous (Institut d'Astrophysique de Paris)
The cosmic matter dipole problem and weak lensing
- Albert Bonnefous (Institut d'Astrophysique de Paris)
11:10 - 11:30
Room: Amphithéâtre 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 this issue, and what are the systematics and specificities that have to be taken into account. In particular, I will talk about weak lensing, and its potential impact on this measurement.
11:30 Full-Field Weak Lensing Inference at LSST Scale with Differentiable, Distributed Simulations - Wassim KABALAN (CNRS APC/IN2P3)
Full-Field Weak Lensing Inference at LSST Scale with Differentiable, Distributed Simulations
- Wassim KABALAN (CNRS APC/IN2P3)
11:30 - 11:50
Room: Amphithéâtre 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 present a scalable, **JAX-based**, fully differentiable forward model for weak lensing at LSST scale. Built on the latest **JAXPM**, it produces spherical shear and convergence (κ) maps and runs efficiently on distributed GPUs; I will describe how we executed the pipeline on the **Jean Zay** supercomputer. I’ll focus on the practical design choices that make end-to-end differentiation and multi-GPU scaling feasible, and outline the next steps toward a complete inference pipeline on realistic survey data, including survey masks, noise, and photometric-redshift effects.
11:50 Probabilistic Inference of Galaxy Properties from Multi-Modal Latent Space Representations - Kirill Grishin (Astroparticle and Cosmology Lab., CNRS)
Probabilistic Inference of Galaxy Properties from Multi-Modal Latent Space Representations
- Kirill Grishin (Astroparticle and Cosmology Lab., CNRS)
11:50 - 12:10
Room: Amphithéâtre 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 and photometric datasets in a common latent space. This framework allows us to infer probability distributions for key galaxy parameters – such as redshift and stellar population properties – by jointly modeling spectral and photometric modalities. Our method provides a scalable probabilistic approach to galaxy property inference across large photometric and spectroscopic datasets, and we have successfully applied it to spectroscopic data from DESI and photometric data from HSC within the HSC-SSP survey area.
12:10 Estimating Rubin/LSST sensitivity to dark matter subhalos impact on stellar streams - Matthieu Pelissier (LPSC/UGA)
Estimating Rubin/LSST sensitivity to dark matter subhalos impact on stellar streams
- Matthieu Pelissier (LPSC/UGA)
12:10 - 12:30
Room: Amphithéâtre 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.
12:30 Cosmology from the Rubin Void Size Function - Pierre Boccard (CPPM)
Cosmology from the Rubin Void Size Function
- Pierre Boccard (CPPM)
12:30 - 12:50
Room: Amphithéâtre 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 on the state of the art theoretical model for the VSF and this project is the first to confront theoretical models to measurements made from voids obtained from photometric redshift tracer data, without assuming a spherical shape for voids. As such, it investigates the impact of statistical and systematic photometric redshift uncertainties on void statistics. Extracted constraints include constraining the dark energy equation of state, sigma 8, the dark matter density, the content of the Universe and the sum of neutrino masses.
12:50 Last words - Johan Bregeon (IN2P3 LSPC)
Last words
- Johan Bregeon (IN2P3 LSPC)
12:50 - 13:00
Room: Amphithéâtre