Has Rindler horizon already been tested experimentally? For an accelerated frame, there is a Rindler horizon at a distance of $$X = \frac{c^2}{a}$$ where $a$ is the proper acceleration. For $a = g$ it is about 1 light year.
If one of that spacial telescopes, like the James Webb, accelerates for a little while in a direction opposed to the direction of the space being observed, all galaxies would disappear in the photos, as I understand. And only a fraction of $g$ is necessary to check this effect, because they are millions of light years away.
However I didn't find in the internet any information of an experiment like that in the past or being planned. It seems an interesting relativistic test, so maybe it has already been done.
There is the cost of losing fuel, and I wonder that vibrations from the engines could mess any photos.
 A: No one has done this experiment because the stars do not suddenly disappear for an accelerated observer - the Rindler observer "outruns" light emitted at a distance $c^2/a$ at the time when the observer is that distance away from it, but the faraway stars have been shining for a long time and there's plenty of light from them emitted a long time ago that's closer to the observer. Think of a line of photons stretching from the star to the observer - the observer is going to outrun the end of that line if they keep constantly accelerating, but all the rest of the photons in that line are going to catch up to them, increasingly redshifted as the observer accelerates away from their source.
Therefore, an accelerated observer doesn't see stuff suddenly vanish behind a horizon, they see stuff behind them slowly redshift into oblivion. But that accelerated observers see redshift is something we already know from observation from earth, we don't need to send a telescope to space to make certain of that.
The more interesting observation related to accelerated observers that is as-of-yet untested is that there should be Unruh radiation coming from the (apparent) horizon, but at ordinary accelerations the temperature for that is so low that we can't really hope to observe it with current tech.
