Have you ever completed the processing of an astro image (say M81 and M82) and then wondered what's the little smudge of a galaxy somewhere else in the image? Well, it happens to me all the time. In this case, I was intrigued by the little galaxy near the top center of the M81/M82 image.
Of course you can look for the object in a planetarium program, but I find that difficult sometimes, due to differing scales and orientations. Also, you need to make sure that the planetarium software has the appropriate catalogs and magnitude limits so that the same objects are being shown. I find that a better solution is to annotate the image with visible DSO's, like my annotated M81 and M82.
Fortunately, Andrés del Pozo has written a very powerful and flexible annotation script for PixInsight, my favorite astro image processing software. All you need to do first is make sure that the image has WCS coordinates in the FITS headers. Andrés has that covered as well - his Image Solver script is also included with PixInsight. One you have the image solved, you just need to choose the web-based catalogs that you want to include, and the annotation style for each catalog. For the example M81/M82 linked above, I just used the defaults:
All you have to do is run the script, and a new annotated image is generated - it's that simple. You can also preview your settings to see if you want to change some of the annotation parameters.
By the way, that little smudge is PGC 28225, a 15.1 magnitude galaxy.