The Simulacrum by Peter Cawdron

Someone is altering old astronomical images. In one small patch of the sky, the digital versions don’t match the original prints and photographic plates taken by observatories from around the world over the past century.
Dawn McAllister is a PhD student tasked with figuring out why Przybylski’s Star is attracting unwanted attention from a malicious hacker… Her high-achieving brother, Ryan, is an astronaut on the backup crew for NASA’s Ample mission to the asteroid Psyche in orbit between Mars and Jupiter… At the same time, NSA analyst Gabriel Rodrigez stumbles upon a collaboration between Russia and China to interfere with SETI, the Search for Extraterrestrial Intelligence.

As the body count rises, it seems that the approach of an extraterrestrial spacecraft over a period of decades is being hidden from both astronomers and the public.