Special Projects
  • Saturn occultation by the Moon in the morning sky - March, 21st 2014
Whereas in Germany it was only a close encounter between moon and Saturn, in Namibia we were able to witness this event on March 21st of 2014 as a Saturn eclipse. The picture on the right shows a simulation with GUIDE. The ingress on the bright side of the moon was at 04:16:51 UT.

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Images - SUN
Images - MOON
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The phase of the Moon was waning, the age of the Moon was 19.8 days and illumination was 80.4%. The egress was around 05:24 UTC. The ingress on the bright side of the Moon was at 04:16:51 UTC.

We only arrived 24 hours prior to the event at Onjala and therefore didn't have much time for setting up the equipment and taking test pictures. The ingress was captured with high resolution in the focus of the C 14 in the 4 m dome using webcam technology. In our 3 m dome we were taking pictures every 10 s during the whole time of the eclipse, using the AstroPhysics EDF-S + 2x Barlowlens and a Canon EOS 60 DA. Using the raw pictures we want to make a movie later on.

The weather was not very good on the evening of March 20th, the clouds were moving only slowly and new clouds were continuously forming above us. Right before the eclipse the sky cleared off and we were able to capture the whole event without any clouds. All following pictures can be enlarged by clicking on them.
From left to the right:

« « « the 4m dome in moonlight

« « the landscape around Onjala in moonlight

« Moon + Saturn with 200 mm telephoto lens
« « Moon and Saturn roughly 3 hours before the ingress, captured with a EOS 6D and a Celestron Onyx refractor at 500 mm focal lenth.

« the C 14 in the 4 m dome of Onjala observatory, which we used to capture the entrance in high resolution

The ingress - technical data

For picture documentation of the ingress we used a Celestron SkyRis camera 445 color (which was kindly lend to us by Baader Planetarium). To take into account the difference in brightness between the Moon and Saturn, we recorded separate Avi sequences for
both images which were taken just before the eclipse (exposure was set on the Moon and on Saturn). The exposure time was chosen in order to make sure that in the Avis of the lunar surface Saturn is still visible. Both stacked images were then, astrometrically correct, assembled in Photoshop. Astrometrically correct means that the orientation of the picture as well as the distance between Saturn and the edge of the moon is displayed correctly.    As a side remark, the following pictures show quite accurately the picture seen visually when using the parallel mounted Zeiss APQ.
« « Composite 03:50 UTC Saturn and 03:51 UTC Moon, approx. 25 minutes before ingress. Saturn 300/3.000 frs, single frame 1/23 seconds. Moon 144/1200 frs, single frame 1/600 seconds.
« Composite 04:11 UTC Saturn and 04:12 UTC Moon, approx. 5 minutes before ingress. Saturn 150/500 frs, single frame 1/23 seconds. Moon 150/500 frs, single frame 1/600 seconds.

In both pictures the different colors of the lava streams on the surface of the moon are easily visible: bluish color = rich in titanium oxide, reddish color = poor in titanium oxide.
For the pictures of the actual eclipse we didn't take a continuous Avifile, instead the image acquisition was done using the single frame mode of the Celestron SkyRis 445C camera. In total we recorded 1.800 pictures (tif format) using a picture rate of 11.5 pictures/s and an exposure time of 1/23 s (obviously, in these pictures the surface of the moon is over exposed).

For the different stages of the eclipse we respectively picked 100 pictures, of which 60 were added up using RegiStax 6.1 to give the Rohsummenbild. A normal Avifile of the surface of the moon was recorded directly after the total eclipse of Saturn, and was fitted geometrically correct using the limb profile of the moon.

» 4 stages of the Saturn occultation
» » All 14 - fairly usable - stages of the Saturn occultation
Unfortunately the seeing conditions decreased rapidly towards the end of the eclipse, which is why the Saturn pictures from the end do not reach the same quality as the early pictures of the eclipse.

The egress - time lapse

As mentioned above, we documented the whole eclipse with the EDF-S refractor. During the whole time a picture was taken every 40 seconds with a 60DA (695 pictures in total). The exposure time was 1/50 second (200 ASA). Depending on the browser, the timelapse can be viewed by clicking or downloading (right-click -> download as) on the following file formats: mp4, webm or Flash
Both pictures below document the exit. The picture on the left shows 6 stages, the one on the right 11 stages of the exit. As always, you can enlarge the pictures by clicking on the previews. The large crater at the terminator is Bürg in the Lacus Mortes.

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All Images and all Content are © by Franz Hofmann + Wolfgang Paech