The above 120 second exposure with 0.8 arcsecond seeing was taken in the 890 nm methane band using a narrow filter (5.0 nm FWHM). The exposure was begun at about 4:06 Universal Time (UT) on November 22 (9:06 p.m. MST, November 21). A central mask about 25 arcseconds wide is used to reduce the scattered light from the disk of Saturn. North is to the top, and East is to the left. The Sun is on the opposite side of the rings from the Earth, and so the rings are a `negative' image of their usual appearance. The C Ring and Cassini's Division are bright while the A and B Rings are dark. This image clearly shows the small Saturnian moons Epimetheus (top of the East ansa, moving East), Prometheus (bottom of the East ansa, moving West), and Janus (bottom of the West ansa, moving West). This image confirms the suggestion from HST observations that Prometheus is about 30 minutes behind the position predicted on the basis of the pre-1995 ephemeris.

This pair of narrow-band 890 nm images were taken at 4:06 UT (top) and 4:17 UT (bottom) on November 22, 1995. Each exposure was 120 seconds long. Appreciable motion of the moons is evident in the eleven mintues between the exposures. A cartoon labelling the objects in each image can be viewed by clicking on the image. The apparent dimming of Mimas (off the tip of the West ansa) in the bottom image is real. During this exposure, Mimas passed through the shadow of Tethys (West of Mimas). A series of 39 such images were obtained between 3:30 and 6:30 UT with subarcsecond seeing and will be analyzed for the presence of even fainter moons or ring clumps not evident in single images.

Click RING MOON MOVIE to see an MPEG (93k) movie created from these images [also SGI MoviePlayer version (11 Mbytes)]. Toward the end of the movie, Pandora emerges from behind the mask, heading West along the bottom of the West ansa, and Mimas passes into the shadow of the rings. Also included is a subset of these images along with the same corresponding cartoons labelling the positions of the moons.

To alleviate the difficulty in viewing the moons through Saturn's scattered light, we performed a boxcar smoothing/dividing technique. This technique makes sharp changes in intensity more obvious while eliminating smooth variations in intensity (like the scattered light). The procedure was as follows:

1. perform a boxcar smoothing on each image
2. divide the orginal image by its respective boxcar smoothed image

This 300 second R-band exposure was taken with 0.8 arcsecond seeing. The image was begun at 02:52 UT on November 20, 1995 (7:52 pm MST, November 19). Saturn was positioned behind a half-mask so that the tip of the main rings was exposed (there is a saturated region by the mask). The orientation of the image is such that North is to the top and East is to the left. Titan is just off the left-edge of the image. There are two bright diffraction spikes emanating from behind the mask. The image has been flatfielded and a preliminary subtraction of the scattered light has been performed. Several radii above and below the ring plane were binned and averaged to produce a "scattered light" image, which was subtracted from the flatfielded exposure. Both Calypso (about 3.5 Saturn radii away) and the E-ring show up nicely in this image.

E Ring Image

Special thanks is due to I.U. graduate student Chris Strom (cstrom@indiana.edu) for his assistance in preparation of this Web page.

Please contact Richard H. Durisen ( durisen@cthulhu.astro.indiana.edu) for more information about these observations.