The HIP 54515 b Superjovian Planet as an Early, Critical Look at the Roman Coronagraph's Performance in the Faint Target Star, Small IWA Limit (2512.07942v1)

Abstract: The Roman Coronagraph's capabilities in the faint star, small IWA limit has enormous scientific (programmatic) impacts. Testing its performance in this limit provides a first look at challenges that may be encountered with the Habitable Worlds Observatory in imaging rocky planets around the nearest K and M stars. We propose such a rigorous test with the HLC/575nm targeting a newly-discovered superjovian planet HIP 54515 b, whose predicted contrast is $\sim$4.7 $\times$10$^{-8}$--2.5 $\times$10$^{-7}$. The companion lies close to the coronagraph IWA (well interior to the TTR5 performance region) and orbits a V = 6.8 star, near the limit for which the coronagraph may yield deep contrasts. Multiple reference stars are available that will further test CGI's performance as a function of $Δ$ pitch angle to assess how the telescope's thermal environment impacts contrasts.