To extend the script in order to distinguish galaxies from stars and nebulas

The current script works well. However it counts every single spots that are brighter than the threshold. It would be useful to distinguish galaxies from stars and nebulas.

- Stars have a rounded shape. They are brighter and cannot be elliptical.
- There are 3 main types of galaxies: elliptical, spiral and irregular. They have a convex circular or elliptical shape.
- Nebulas have an irregular shape.

In addition, the brightness threshold should be a little lower for both galaxies and nebulas.

Start by locating the current script or notebook section that applies the brightness threshold and counts spots. Review how detected shapes are represented, then define and validate the galaxy, star, and nebula distinctions and their lower brightness thresholds; done means the output no longer counts all bright spots as one category.

Written by the indexing model from the issue text.