Creating the Saturn observation form

The Saturn observation form can be found here:

Saturn observation form

Why did I make the form?

Some time around 2001 in connection with Iván Éder's Saturn drawing I was faced with the fact that the actual Saturn observation form was inaccurate. The markers used for the rings were on wrong places. Furthermore they needed to be removed from the paper with a knife at the end if you didn't want them to spoil the drawing. That old observing form didn't even indicate the outline of the ring. The newer observation forms of the Hungarian Astronomical Association indicate the ring but the basic problem is that we see the planet and its rings at a different angle every day. So in theory an infinite number of observation forms would be needed. The solution I've seen everywhere is there are a couple of ready forms (3 - a good dozen). But if the real tilt of the rings visible in the telescope doesn't match that of the preprinted form then I think the drawing is not good.

A Change of Seasons on Saturn
A Change of Seasons on Saturn. Credit: NASA and The Hubble Heritage Team (STScI/AURA), Source:

So far the lack of a proper observation form kept me from drawing Saturn. I don't have a single drawing of the ringed planet that would be worth mentioning. But some day I would like to make a nice drawing of Saturn.

The problem

So I needed an observation form that shows the Saturn globe and the rings for an arbitrary tilt angle. It also needed to be vector graphics so that it can be enlarged arbitrarily without ever getting pixelated. I wanted many options so that the form can be modified to be appropriate for any telescope size and printer.

The solution

A website using SVG (Scalable Vector Graphics), JavaScript and CSS media queries represented a perfect medium for the observation form. Some math was necessary as well because the shape of the oblate Saturn globe (approximated with an ellipsoid) changes with different tilt angles as well. Using a little coordinate geometry and trigonomerty I managed to derive the appropriate transformation formula relatively fast. Then I needed precise data about the size of the planet and its rings. These were obtained from Wikipedia: Saturn, Rings of Saturn.

Then it was time to realise the project. Of course a few smaller problems arose during coding but overall it was pretty straighforward.

The advantage of the online form is that it is accessible for others as well.

Saturn observation form