In part 1 I discussed a basic approach to indexing stars and their corresponding labels. I extended this approach further to include deep-sky objects from the NGC catalog. I'll also add the IC catalog, and cross-references to other designations such as Messier number.
In order to cater for orientations of galaxies, I used a textured, indexed quad instead of a point sprite. This enabled me to scale and rotate the texture appropriately. You can see this in Figure 2 with NGC 224 (The Andromeda Galaxy, M31). For the time-being I will use a simple sprite to represent the size, shape and orientation, and will extend this to images in the future.
Strictly speaking, since the deep-sky objects are not point-sources, I should be using an alternative spatial indexing approach, since it is possible for an object to span cells in my simple grid. However, the maximum object size is relatively small in comparison with the grid size so this shouldn't be a practical issue.