As with all extended objects, the published magnitude is the brightness the object would have if all it's light were consolidated into a single point source. For the Helix, the 6.5 magnitude point source is spread out into an area almost half the size of the full moon, resulting in extremely low surface brightness. The Helix is a very difficult object to find and observe visually. With a declination of -20 degrees, the Helix does not rise very high in the sky for many locations.