Try this http://hacks.atrus.org/neopets/findConstellations.fcgi You need to get your star data, right here http://www.neopets.com/altador/astro.phtml?get_star_data=1
Did you try both the links that luishem and I gave you? The Stargate does work, I didn't have any luck with the Neohack on but I think I missed a step. The first consellation is hard to find, but after that you get the hang of it (and you can use those stars are reference points). If neither works, you missed a step in the plot.
Use the bright stars as reference points. That's how I did mine. So, if your next constellation if to the right of The Sleeper and seperated by three blue stars, find those stars, reference them, and use them to find the stars in the consellation. It's easier than just trying to find the constellation without..