The tattooing went very well. And it was fast! My appointment was for 11:30, and I left at about 1:00. My tattoo artist, Paul, said that the process went quickly in part because I'm good at not squirming and because my skin absorbs ink quickly. I was surprised when he announced that he had finished--and glad, too, since the left side was starting to sting quite a bit.
I don't yet have any pics of the actual tattoo. I brought my camera along and intended to have Jeff take a picture before Paul bandaged up the tattoo, but that whole area of my skin is a very bright shade of red right now, so I'm going to wait on photos until the irritation subsides. Until then, I can offer you a couple of images. One is a very important message:
And the other is a scanned image of the design from which the artist was working:

I got the image from Roderick and Marjorie Webster's WESTERN ASTROLABES, which is from a series of volumes called "Historic Scientific Instruments of the Adler Planetarium & Astronomy Museum." About the drawing, the book says
THE SPHERICAL ASTROLABE - This astrolabe was described in the "Libros del saber" of Alfonso X of Castile (1221-1284). The stars and ecliptic circle are shown on a rete that takes the form of a cut-out spherical shell. This shell encases a ball on which are marked the horizon, altitude lines, azimuths, etc. Several small holes in the ball permit moving the pivot to adjust the instrument to the proper latitude.
The actual tattoo is about the same size as the image you see above. Some of the detailing had to be left out, but not much.