Bounties attract serious brainpower to the challenge.
A circular, dome-shaped tombstone with a mini-map of a night sky pressed on it. All the major stars and constellations on the tombstone are facing the sides of the sky in which they originally were at the time of death or burial of the deceased.
It's a solution to this problem.
Souls are often associated with stars, the connection between souls and stars is often romanticized, there's an allegoric meaning to it. For example, there's a saying/belief that each time a person days, a new star is born in the sky. Such tombstones marking the position of stars and constellations on your death day/hour would emphasize this allegoric meaning.
The exact position of stars and constellations at the time of your birth is significant in astrology. Nobody cares about it regarding the moment of your death, though. Make this different.
The relatives/friends of a deceased could come each year on the day of their death in the evening/at night and watch the positions of stars and constellations on the tombstone match those seen in the sky.
Honor the deceased with a unique tombstone.
How it works:
The cover image is a bit misleading of what I have in mind. I imagine a rather small dome of stone, something like this, just bigger, taking the space of a part (a half, a quarter or so) of a traditional grave. The stars and constellations would be represented by thin, coin-like metal dots pressed on stone similar to these:
To make a tombstone with a sky atlas of a particular, fixed moment in time, you have to first take a "screenshot" of a night sky at that time. This can be done with a specialized app.
The precise (or approximate, if the precise is not known) time of death of a person is indicated in their death certificate. You enter the time and coordinates in the app and it produces a detailed night sky image that the observer would see at that time from a particular location (it could be the location where the person died or where they will be buried).
The map of a night sky can also be easily extrapolated into the future in case the positions of stars/constellations during the funeral are desired to be carved on the tombstone. A sculptor then makes the tombstone according to the blueprints produced by the app.
During the funeral, be it burying of the remains, or the urn with ashes, the tombstone is placed (either by workers or machinery, if it's too heavy) on a metal axis and turned until it takes the correct, planned position, making it a miniature night sky replica of a specific time. Then that position is fixed by pressing the whole structure down or by other means.
In case of cremation, the ashes of the deceased could be integrated into the tombstone while making it. A cemetery with a green lawn, full of such tombstones would look classy. One could implement additional cool features such as lighting the tombstone when the positions of stars and constellations in the sky match those on the tombstone (each year during the death day of the deceased).
This could bring a novel tradition of burying people in the late evening (around midnight) so that all the attendees of the funeral could compare the positions of stars/constellations in the night sky with the replica on the tombstone.