Saturn's main satellites
Magnitudes at opposition
| I Mimas | II Enceladus | III Tethys | IV Dione | V Rhea | VI Titan | VII Hyperion | VIII Iapetus |
| 12.9 | 11.7 | 10.2 | 10.4 | 9.7 | 8.3 | 14.2 | 10.2 - 11.9 |
This Java applet displays the 8 brightest satellites orbiting Saturn. The view is non-inverted, so East is on the left and West on the right. Any moons which are further out than the extent of the display area are not listed. Iapetus sometimes falls into that category. The applet does indicate whether a moon passes in front of or behind the planet. So if a moon is listed at the top but is not visible it must be behind the planet. An ellipse shows the extent of the rings (out to the edge of ring A).
The calculation scheme is given in the excellent book by Jean Meeus: "Astronomical Algorithms", 2nd edition (corrected August 2009), Willmann-Bell Inc. The scheme given in chapter 46 is used, with the accurate VSOP87 method (Chapter 32 and Appendix III) for determining the position of Saturn relative to the Earth. The ring aspect is calculated according to Chapter 45.
I wrote the applet in order to identify satellites visible in a photo of Saturn I took on 7th March 2010, grossly overexposed as far as the planet is concerned, to see how many satellites I could detect:
Canon EOS 5DMkII 254mm Newtonian @ 1200mm 10s f/4.8 ISO1600 2010:03:07 22:34:46
From the Julian date dialogue in GRIP (on the Config menu) I found that 2010:03:07 22:35:00 was JD2455263.44097 which I entered into the applet above to get this diagram, which should be compared with the photo above:
From that I deduce that my photo can be labelled like this (Saturn was only a few days past opposition so the magnitudes are about right):
There appears to be another possible satellite on the right but I guess that must be a star. I should check that. Of course taking a series of photos an hour or so apart would be the way to show which points of light are really satellites. I have not yet tried to do that.