Good effort Mark, but you needed to tone down the highlights so that 47Tuc
starts to look like the glob that it is rather than a washed out star, and also The Tarantula Neb will identify itself by showing some colour.
raymo
Most people will probably do it differently but as you already have Gimp it makes it easy.
Heres what i do. shrink down the image to the physical resolution that i would like by going Image > Scale Image.
After that i go File > Export and export the file a as a JPG. When i export the file it will give me a quality slider. Its a bit of trial and error but I generally set it to around 70-90% until i get the file of the size IIS requires.
I believe that IIS will reduce the image somewhat and i heard people mention you can upload a file that is 1.2mb in size and it will reduce it automatically but i haven't tried that.
You can also sign up and upload the image to Astrobin for high quality uploads + annotations and equipment information. You can get 10 free images with their sign up then paid after that.