The Hubble constant from two sibling Type Ia supernovae in the nearby galaxy NGC 4414: SN 1974G and SN 2021J

Having two “sibling” Type Ia supernovae (SNe Ia) in the same galaxy offers additional advantages reducing a variety of systematic errors involved estimating Hubble constant, H 0 . NGC 4414 is nearby included Space Telescope Key Project to measure its distance using Cepheid variables. It hosts sibling SNe Ia: SN 2021J and 1974G. This provides opportunity improve precision previous estimate , which was based solely on Here we present new optical BVRI photometry obtained at Observatorio de Sierra Nevada complement it with Swift UVOT UBV data, cover first 70 days emission 2021J. A look spectra Gran Telescopio Canarias (GTC) reveals typical type features. The main luminosity parameters for are by SNooPy, light curve fitting code templates. Using hierarchical bayesian approach, build diagram sample 96 from Combined Pantheon Sample redshift range z = 0.02 − 0.075, calibrate zero point type-Ia 4414. We report value constant 72.19 ± 2.32 (stat.) ±3.42 (syst.) km s −1 Mpc expect reduction error after analysis Cepheids period-luminosity relation upcoming Gaia DR4 HST JWST.