Assuming that the photographs include the entire sky of the alien planet and includes magnified telescopic images, the civilization that receives the photographs may be able to pinpoint the location that the photographs were taken at. Thus the alien civilization might receive thousands of separate photographs to cover the entire sky of the mystery planet.
If the Milky Way is visible in the sky of the alien planet, the alien planet must be within the disc of the galaxy. The disc of our Milky Way galaxy is about 100,000 light years in diameter and about 1,000 light years, or a few thousand light years, in thickness "up" or "down".
If the apparent diameter of the central bulge of the galaxy is measurable from the photographs it can be compared with the actual diameter of the central bulge to deduce how far the mystery planet is from the center of the galaxy.
If some of the photographs and "photographs" covering the center of the galaxy are made in the proper wavelengths of electromagnetic radiation, it may be possible to calculate the precise direction to the super giant black hole at the center of the Milky Way Galaxy.
The central points of the Andromeda Galaxy, M31, and M32, an elliptical satellite of M31, should be easy to locate from most parts of the Milky Way Galaxy. And the central point of galaxy M87 in the center of the Virgo Cluster should be easy to locate.
So by comparing the angles between those three or four directions it should be a simple trig problem to plot the approximate location of the mystery planet.
The directions to a few globular star clusters in the Milky Way Galaxy should help narrow down the position of the mystery planet. Some globular star clusters are bright enough to be visible to the naked eye at distances of over 10,000 light years, so if the photographs of the sky are telescopic some globular clusters should be detectable and identifiable. That shoud pin down the position of the rogue planet more precisely.
If the civilization that receives the photographs is as advanced in astronomy as early 21st century Earth it should have some data on the directions,distances, and absolute magnitudes of many of the stars within a few hundred light years of the rouge planet's position. So once the position of the rogue planet is narrowed down to a vaolume of space several light years on a side that is 1,000 light years away, the directions to the brightest stars in the sky of the rogue planet and their apparent magnitudes compared to other astronomical data available to the civilization receiving the photographs should be enough to calculate a much more precise position for the rogue planet.
And the civilization could use infrared sensing telescopes to try to directly see the infrared radiation emitted by the rogue planet at its temperature, and thus directly locate the rogue planet.
So the civilization that receives the photographs should be able to narrow down the position of where the mystery planet was when the photographs were taken. How long did it take for the photographs or the information needed to digitally construct them, take to reach the alien civilization 1,000 light years away?
Were physical photographs dropped off by a slower than light ship that took 100,000 years to make the journey, or dropped off by a faster than light ship that took only a single year to make the journey? Was the data to reconstruct the photographs transmitted by radio at the speed of light taking 1,000 years, or by a faster than light "hyperwave" transmitter, or by an instantaneous Dirac transmitter?
Assuming for the moment that the information took 1,000 years to arrive, the rogue planet should have an orbital velocity differing from that of the investigating civilization by approximately 10 to 1,000 kilometers per second. There are 60 seconds in a minute, 3,600 seconds in an hour, 86,400 seconds in a day, and 31,557,600 seconds in a Julian calendar year.
So there would be 31,557,600,000 seconds in 1,000 Julian calendar years. At a speed of about 10 to 1,000 kilometers per second, the rogue planet would travel about 315,576,000,000 to 31,557,600,000,000 kilometers in 1,000 years.
A light year is defined as 9,460,730,472,580,800 meters, or 9,460,730,472,580.8 kilometers.
According to my rough calculations, in 1,000 years the rogue planet will probably move about 0.033356409 to 3.335640952 light years from its previous position. Its new position should be somewhere within a cube 0.0667 to 6.671 light years on each side, centered on its old position. Of course it is possible that the civilization receiving the photographs can deduce something about the speed and direction the rogue planet is traveling and can narrow down its current position more precisely than that.
And similar calculations can be made with other assumptions about the situation.
Suppose that the photographs don't come from a rogue planet but from a planet that orbits a star. In that case a similar process should be able to narrow down the approximate position of the planet. Once that is done, any information about the spectral type or the precise spectrum of the star it orbits should help the receiving civilization to identify that star by comparison with astronomical data about stars in that region of space.