And so with nothing more than an inexpensive six-power comparator, I measured diameters of some 40 randomly selected stars with visual magnitudes between 2.0 and 11.5. Now, without having to chase down tabulated magnitudes, it's possible to make diameter measurements and quickly assemble a series of standard stars near a new comet or variable with magnitudes nearly as accurate as the measurements of modern-day Earthbound photometrists. Had I used more stars and a better comparator, the precision would have been substantially better. Similar measurement of the separation ticks for 33 double stars also had good agreement. The errant point, whose tick is partly blocked by a faint star, is the distant giant Eta Persei.
Variable stars receive an interesting and useful treatment.
Finally, a few hundred additional variables are plotted as open circles. These are known to have a maximum brightness of at least 9th magnitude but were not detected because they happened to be too faint during the Hipparcos mission. Double and multiple stars likewise receive an innovative treatment. To convert tick lengths to separations in arcseconds, the authors again provide a simple formula. A novel feature of MSA is the indication of proper motions greater than 0.2 arcseconds per year.