The November 3 2013 eclipse was a rare Hybrid
eclipse. See the explanation below for more information on
Hybrid eclipses.
To summarize the longer writeup below, in a Hybrid eclipse the apparent
sizes of the moon and sun are almost the same. Where we were
on the track the moon was just
larger than the sun. Thus we saw a total eclipse. Since
totality for us was close to local noon, we were also almost at the
point of greatest eclipse (where the moon's apparent size was the
largest).
Since this eclipse occurred near solar max we expected a large number
of prominences and an active corona. We were not
disappointed. Rick
Fienberg, our resident astronomer, predicted that prominences
might be visible during the entire event. That is what
happened
I must confess that this is the first eclipse where I never noticed the
corona. While I was taking pictures almost continuously, the
camera was preset. All I was doing was pressing the shutter
which I did without too much concentration. What disrupted my
normal viewing pattern was that chromosphere and prominences were
indeed visible throughout the event. In other eclipses I
changed my view to the corona when I lost sight of the prominences.
This time my eyes were looking around the rim of the sun for
the full 90 seconds. I don't remember any details of the
corona.
Heading South
We left Dakar, Senegal on Nov 1. The weather prospects for
our
original site were poor so after talking with the meteorologist
Jay Anderson, the boat made the decision to target a site further down
track. The target location was 05 56N
17 03W. That meant pushing the boat for more speed.
Since the engines are electric, the A/C was reduced.
We also had a very rough ride, but that was what it took
Sunrise
Not exactly clear weather at 6:48 AM. C1 was to occur at 10:50 and we
were still sailing south so there was
some time.
By 11 AM clear spots were sighted that would be on
the eclipse track the boat turned and the skies opened. By C1
the sun was in the clear. This map shows our actual location at the
time of totality. Since I could not get the location to
exactly agree with our actual location of 5.751667N 16.63W
the times displayed are a couple of seconds off.
These were taken with a Canon 20Da using an EF 300mm IS lens.
My plan was to use a monopod to steady the camera. During a
practice session before eclipse day I learned that the ship may be
moving too much to use the monopod. In fact, I hand held
during totality.
All photos were taken at ISO 400, f/6.3 in Canon RAW mode.
The camera autofocused before C2 and then I turned autofocus
off. The shots were manual mode with 2 stop bracketing
centered on
1/1000. Times are approximate since I cannot sync the camera
to seconds. Use the times only relative to each other.
All of the images are displayed at reduced resolution. Click for a full size image
12:28:06 1/4000 2nd Contact
12:28:06 1/1000 2nd Contact
12:28:08 1/250 (processed by iPhoto)
12:28:10 1/1000 (Shortly after 2nd contact)
12:28:10 1/4000
Processed by iPhoto and TGVDenoise via PixInisight
12:28:51 1/250
Processed by PixInsight
Processed by iPhoto
12:29:12 1/1000
12:29:12 1/4000
Processed by iPhoto. Noise reduction using TGVDenoise in PixInsight
12:29:42 3rd Contact
Watch Us Watch the Eclipse
Watch the Eclipse From Space
Source http://www.sat24.com/history.aspx
What Is a Hybrid
Eclipse?
Eclipses happen at all because the apparent size of the moon and the
sun are approximately
the same. The sun's apparent size varies between 31.6′ –
32.7′. The moon's orbit is more elliptical and varies between
29.3′ – 34.1′. When the moon's apparent size is at its largest relative
to the sun's
then a long total eclipse occurs. When the size is smaller,
like in May 2012,
then an annular eclipse occurs. A Hybrid occurs when the ratio is right
on the tipping point of 1:1.
The moon's apparent size changes when the earth is further away.
The size is always greatest at the noon location because the
earth is curving toward the moon. Normally this just changes
the length of totality, but during a hybrid eclipse the distance is so
critical that even this small amount is enough to reduce the apparent
size below 1:1. In the farthest location the moon no longer
covers the sun which results in an annular eclipse. Near B the apparent
size of the moon is larger so a short total eclipse occurs.
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