|
|
|
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.
Back to Special Projects |
|
|
|
|
|
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. |
|
|
|
All Images and all Content are © by Franz Hofmann
+ Wolfgang Paech |