URANUS and ITS SATELLITES

The following images show Uranus and its four brightest satellites at various locations in their orbits.  The sequence of images also shows Uranus moving through a field of distant stars during a typical year's opposition (retrograde) motion.

Figure 1.  Minimal editing version a CCD image taken 2001.08.25.283, showing at least 3 of its satellites. Image area is 9.2 x 6.1 'arc. [Meade LX200 10-inch f/6.3, 416XTE CCD imager at prime focus, 3-second exposure.]

The disk of Uranus is actually much smaller than it appears here, being only 3.5 pixels in diameter (3.7 "arc).  The satellites have magnitudes of 14.0, 14.2, 14.4 and 15.0.

Figure 2.  Two-times zoom detail of same image after subjecting it to a filter-enhancement that emphasizes small structures while distorting large ones.  The four satellites are Oberon (bottom, 7 o'clock), Ariel (closer in at 7 o'clock), Titania (4 o'clock), and Umbriel (2 o'clock).

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Eight days later Uranus has moved into a different star field, and the moons have different locations.

Figure 3.  This 1.5-second exposure (taken 8 days after the previous images) shows the same four satellites but in new locations.  Image area is 14.1 x 9.3 'arc. [Meade LX-200 10-inch SCT, Meade Pictor 416XTE CCD imager, residential site, 2001.09.02/03, September 3.24 UT].

Figure 4.  Zoom factor of two.  Average of 20 exposures, each 1.5-seconds, of a 3.4 'arc square region centered on Uranus.  Contrast enhancement was achieved using FFT high pass filtering.  North is at the top.  Four satellites can be seen:  Oberon (top), Titania (bottom), Ariel (close below) and Umbriel (very close on right).  Three background stars are present (upper right and lower-right). [2001 September 3.24 UT].

Figure 5.  Two times times enlargement of same image, showing satellites orbits indicated by dotted patterns.  The outermost orbit is that of Oberon, which is close to its most northerly location (which has orbited slightly more than half way around its 13.5-day orbit since the time of Figures 1 and 2).  The next orbit inward is that of Titania, located at the 5 o'clock (it has almost coompleted an entire 8.7-day orbit since the August 25 image).  Next inward is Umbriel, which is barely visible at the 3 o'clock location.  The innermost orbit is that of Ariel, which is at the 6 o'clock location. Each satellite is within a pixel or two of its predicted location.  The satellite magnitudes are 14.2, 14.0, 15.0 and 14.4 (Oberon, Titania, Umbriel and Ariel).  Uranus has a diameter of 3.7 "arc, and would be 3.5 pixels in diameter if it weren't overexposed.  Image scale is 1.1 "arc per pixel.  The "atmospheric seeing" was especially good this evening.  [LX-200 10-inch f/6.3 SCT, 416XTE CCD imager.  Average of 20 1.5-secopnd exposures. 2001.09.03, 5:45 UT]
 


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This site opened:  September 3, 2001 Last Update:  September 4, 2001