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Voyager 1 at Saturn Revisited, Forty years ago this month (November 2020)
Ian R
post Nov 5 2020, 06:22 AM
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On the cusp of midnight between the 4th and 5th of November, 1980, Voyager 1 took this mosaic of Saturn via its narrow-angle camera:

Attached Image


45 black-and-white TV frames were combined to form this image. The observation was noted in the documentation as a: "3 color 3x5 mosaic of Saturn + rings".


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Bjorn Jonsson
post Nov 12 2020, 11:46 PM
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Exactly forty years ago today Voyager 1 flew by Saturn with closest approach occurring on November 12, 1980 23:46 UTC at a range of 184,000 km from Saturn's center (and interestingly, due to Saturn's oblateness Voyager 1 reached minimum distance from the cloudtops slightly later). With the exception of Titan its satellite images are now mainly of historic interest. In contrast, the images of Saturn are still of interest because the appearance of Saturn's atmosphere changes with time (both seasonal changes and non-seasonal changes).

Below is a small sample from an ongoing image processing project; I'll probably post more images later. The focus here is on reprocessing and improving some of the images that were released 40 years ago. The only exception is the false color GR-VI-UV global image which is 'new'. It is similar to an image released 40 years ago but I decided to use different source images because I wanted a better UV image (many of the UV images are smeared).

A GR-VI-UV color composite:
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An OR-BL-VI color composite showing the northern hemisphere in approximately true color/contrast and a greatly enhanced version:
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This filter combination is not optimal for true color images but nevertheless I was fairly happy with the true color version. The enhanced version has been heavily processed to reveal subtle color differences. The blue areas are areas where blue color is a bit stronger relative to red/green than elsewhere but they are not blue; they are simply slightly less yellow than other areas. In the red areas the red color is slightly stronger relative to green/blue than it is elsewhere etc. A bright convective feature above center is prominent; I was careful not to 'saturate' the brightest area during processing. Interestingly, the processing reveals that the color of the northern half of the bright band containing the 'ribbon' differs slightly from the color of its southern half. A version of this image showing a smaller area was released 40 years ago.


An OR-BL-VI color composite showing the southern hemisphere in approximately true color/contrast and a greatly enhanced version:
Attached Image

Attached Image


The processing is comparable to the preceding image except that the enhanced version isn't quite as heavily processed. A small spot at planetographic latitude ~54 degrees south is visible near the limb. Interestingly the spot is obvious in the OR and VI images but it is almost completely invisible in the BL image. In the OR image it appears brighter than the surrounding areas whereas in the VI image it appears darker. Enceladus is visible at upper right. A version of this image showing a smaller area was released 40 years ago.


A reprocessed approximately true color/contrast global image (it appeared at e.g. the Planetary Society website several weeks ago):
Attached Image


This image is is processed from the last set of images completely showing Saturn and the rings in a single set of images. Dione is obvious near Saturn but Mimas is also faintly visble below and to the right of the rings near the right edge of the image.
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