The list of categories has been updated, and 'Nebula and Star Cluster' are grouped together.
Image submissions opens at 9am tomorrow, 1st May. The link to the image submission form is on the info page (along with any guidelines, rules and the full list of categories):
http://www.iceinspace.com.au/73-685-0-0-1-0.html
I finished coding just in time to have the image submission form ready for tomorrow, and although I tested as many scenarios as I could, it's possible some bugs still remain. If you have any problems submitting images, please simply get in touch with me via PM or email.
Once you have submitted your images, they cannot be removed in order to upload any others. I didn't get time to code a 'delete image' function
Good luck and have fun!