As the saying goes, there’s a tool for every job. So if your next observing session involves drawing globular clusters, you might want to add a tortillon to your sketch kit. It’s a hollow cylinder of tightly wound paper with a tapered point at one end that, similar to a blending stump, you can use for drawing or smudging marks.
While sketching, you employ the chamois-like blunt tip of a blending stump to render the cluster’s soft glow. A tortillon’s firm, sharp tip, on the other hand, is ideal for stippling the unresolved stars within it. Stippling is a type of shading that uses small dots. To stipple, lightly touch or tap the tortillon to the paper as many times as necessary to produce the effect you want. I’ll demonstrate by looking at two attractive globulars in the constellation Delphinus the Dolphin.
Astronomy magazine subscribers can read the full column for free. Just make sure you're registered with the website.