Roohi Dalal, Princeton
New Cosmology Constraints from the Hyper Suprime-Cam Year 3 Data Release
The Hyper Suprime-Cam (HSC) survey is the deepest Stage III weak lensing experiment, going to ~26 mag with exquisite seeing. The depth and image quality achieved by HSC allow us to probe cosmology using weak lensing up to high redshifts, and these analyses serve as important preparatory studies for the next generation of weak lensing surveys. I will discuss our constraints on cosmological parameters using weak lensing cosmic shear power spectra measured from the Year 3 shear catalog of HSC, covering 416 square degrees of the northern sky. I will describe our cosmological analysis, including the steps we take to prevent confirmation bias as well as our modeling of various sources of systematic uncertainties. I will then discuss our new constraint on the S8 parameter, which describes the clumpiness of the matter distribution, and how it informs our understanding of the apparent 2-3 sigma tension between constraints on S8 from weak lensing experiments and those from the CMB. Finally, I will discuss ongoing and future work that can further shed light on the S8 tension, including an improved modeling of baryonic feedback at small scales.

Danielle Frostig, MIT
WINTER—a new near-IR survey telescope
The Wide-Field Infrared Transient Explorer (WINTER) is a new near-infrared time-domain survey instrument installed on a dedicated 1-meter robotic telescope at Palomar Observatory in June of 2023. WINTER’s science goals include robotic follow-up of kilonovae from binary neutron star (BNS) and neutron-star black-hole (NSBH) mergers, surveys to study galactic and extragalactic transients and variables, along with building up a deep, coadded image of the near-infrared sky. The project also serves as a technology demonstration for new large-format Indium Gallium Arsenide (InGaAs) detectors for cost-effective near-infrared photometry without cryogenic cooling. WINTER’s custom camera combines six InGaAs detectors with a novel tiled fly’s-eye optical design to cover a >1 degree-squared field of view in the Y-, J-, and shortened-H-band filters (0.9-1.7 um). In this talk, I will present the design, performance, and early on-sky results from the WINTER observatory.