Very nice image of a cluster core- except there is no "central" galaxy! Which one am I supposed to classify? Thanks for the help!
It's not so easy to see which is the one in the center, but maybe this will help: I think it's the central of the three more or less in a ~horizontal line, in the middle. In some Z projects there has been at least the option of putting a grid on the image to be classified (Comet Hunters, for example, has a grid). I do not know why such an aid was not implemented for this DECaLS set of images.
I have found that a piece of tracing paper with a square the same size as the image, helps. I draw a pair of diagonal lines from the corners, and where they meet is the center of the image.
Hope this helps, and happy hunting! 😃