see my German language
translated site! Welcome to
see my German language
translated site!
We observed the first
eclipse of the millennium in Zimbabwe near Muzarabani, close to
the Zambesi escarpment. Our camp was at 31° 01,45' east, 16°
24,90' south, 487 m height. Our group has had nearly 100 members,
the tour was organised by Astronomie.de.
Contact times (local time = UT + 2h), calculated with AstroWin and EmapWin:
Sunrise 6h23m, sunset 17h32m in Mavuradonha SoFi Camp; ET-UT = 66 sec
AstroWin EmapWin
h m s h m s Pa Nord Pa Zenit Azimut Elev
1. Cont: 13:48:32 13:48:32 272 128 325 42
2. Cont: 15:13:29 15:13:31 115 349 309 28
3. Cont: 15:16:42 15:16:40 251 127 308 27
4. Cont: 16:28:49 16:28:49 94 339 299 13
There were no corrections to lunar limb profile.
To enjoy the eclipse, i controled several photo cameras with an
electronic orgniser (Psion Organiser II), which also recorded
weather measurements. More details below!
I took photographs on Fuji Velvia color slide film. To show
details over the total corona, i made composits of slides with
different expositions from 1/1000 s to 4 resp. 8 secs. First
results can be seen below. For more enlarged pictures: click on
them!
left: 8 photos with 1m focal length (MTO-11 CA, f= 1000 mm
1:10)
right: additional with 500 mm tele (MC 3M-5CA, f= 500 mm 1:8),
exposure times from 1/1000 s - 8 s. Download
large picture (153 kB)
Some of my partial phases photographs are sandwiched to simulate a
row exposition:
The shadow bands
For obtaining pictures of the shadow bands, we
videotaped a 1.4 * 2.4 m large white cloth on SVHS videotape.
A 3-seconds MPEG-1-Video (552 kB) is
downloadable here (add 5 sec to timestamps!).
Two single frames of our video are shown below, videotaped by Andreas Dahm. Time is UT +2h:
The shadow bands were visible on the
original video form 15:13:03 to 15:13.33 (2nd contact at 15:13:34
incl. limb corr.) and from 15:16:45 to 15:17:03 (3rd contact at
15:16:40).
For showing the shadow bands on still pictures, i substraced an averaged picture (averaged from 25 single frames = 1 second) of the procection cloth from the original video sequence, using a 50% transition effect with of my video software.
Otherwise you see only structures of the cloth, as shown on the left...
My video was presented at the first Totality
Day
2001 in Milton Keynes/England.
Discussion of the shadow bands video:
For analyzing my videos i superimposed
an inverted sum-picture from 25 frames (= 1 sec) to the original
video track with 50% transparency with my video software (Ulead
Media Studio). So the unsettled background vanishes for measuring
the cahanging structures in the picture. A 0.5 m square grid
(green), cross with suoth and est indicator (blue), solar
direction (azimut 308°, red) and a solar picture (cortesy
Gebhard Oelmeier!) is also superimposed. There might be
slight unaccurancies with the orientiation (10°..15°), as i did
not check them at the observation site. I had to extract
these values at home from plant shadows on the videos...
Watch videos on Youtube for the second contact and third contact
2nd contact:
Before the 2nd contact, the shadow bands were
very clearly visible. They moved nearly directly towards the sun
(slight deviation to south-west) and their extend was
perpendicular to that.
Their wavelength decreased from ca. 0.2 m .. 0.3 m (i. e. spatial
frequency 3 .. 5/m) at about 18 seconds before 2nd contact to 0.10
m .. 0.15 m (i. e. spatial frequency 6 .. 10/m) at 10 seconds
before 2nd contact.
Their contrast increased from about 1.2% .. 1.8 % (at -18 sec) to
2 % .. 3.5 % (at -10 sec).
Speed was about 1 to 1.4 m/s in solar direction (i. e. 309 deg.
azimuth). On our video they can be seen for 30 sec.
3rd contact:
After 3rd contact
they looked much more different. No one of our group saw them, but
our video shows them for about 18 sec, lasting shorter, however.
Furthermore, they looked much more turbulent at remarkably lower contrast, not like the perfect bands before 2nd contact. In general they extended in north- southern direction and moving to west with appr. 1 .. 2 m/s speed. Their wavelength was 0.10 m .. 0.15 m (i. e. spatial frequency 6 .. 10/m) 7 sec after 3rd contact.
In both cases (2nd and 3rd cont.) the survival time of the single cells was in the range of about typical 0.5 sec to max 1 second.
The cause of the different orientation is the
different inclination of the solar crescent to the horizon before
and after totality. They are always orientated, as if they are an
image of a distant lens. Only exactly on the centerline there will
be no rotation of the bands before and after totality.
Note the position angles. At 2nd contact (p.a. 349° to zenit), the
crescent lied nearly parallel to the horizon, and the shadow bands
seemed to extend perpendicular to the solar direction. mAfter 3rd
contact, the crescent was inclinated 43 deg to the horizon (p.a.
127° to zenit), and the shadow bands were also inclinated to the
solar perpendicular line by appr.
50°.
To study contrast an the development of the shadow bands in
detail, i took with LIMOVIE
the intensity profils of a four pixel area of my cloth. With
SPECTROGRAM
i made a power spectrum of the intensity plot. The upper graphs
show the spectrum befor resecond contact (marked as C2), the graph
right the development after third contact (C3). It can be seen,
that the shadow bands do not develop continuously, but that there
may occur short periods of less activity.
For more details see my shadow bands explanation page!
See Eric Flescher's very fine overview and linkpage of other shadow band sites!
We had furthermore recorded the approaching an vanishing of the moon's shadow with three cameras on video. download here a quick-motion clip of those cameras (7 seconds, MPEG-2, 530 kB). (If you get problems in playing MPEG-2 files, download VLC media player or Microsoft's newest newest media player. The standard one often does not play MPEG-2.)
Simulation of the eclipse for central
Europe. Download large picture (157 kB)
the orange line indicates the sky brightness at eclipse da and the day after in log scale, the red graph shows the temperature at 4-5m height, the grenn graph temperature at ground level and the blue line wind speed.
The eclipse and sunrise and sunset are marked.
More detailed graph for the time of eclipse:
Note that the temperature at ground level has a higher amplitude and reaches it's minimum later the higher levels in the atmosphere.
The central parts of the eclipse.
The asymmetry along the mid of the eclipse my be caused by an
improper time calibration.
Minimum sky brightness was about 2.8 lux.
(Maximum daylight brightness: 120000 lux!)
Tables with my complete
measurements for download (7 kB text) and zipped tiff-files (317 kB) in full
resolution.
Nice to compare: Bill
ronald's
temperature measurement (nearly the same place as ours!)
My Equipment. Courtesy
Gisela Bertram for this qolden snapshot!
As mentioned, a Psion organiser II recorded weather measurements and photo cameras. More details on my eclipse Organiser webpage (German) and my technical documentation of the interface (English).
my combined wind and temperature and brightness sensor.
1) Brightness
The sensor is the circuit "TSL230" (Texas Instruments), which converts light intensitiy to a frequency. It is mounted under a diffusor dome. The circuit can be varied in its sensitivity by canging the sensor chip area by a factor of 10 or 100. Additionally, the output frequency can be divided by 2, 10, or 100. So you get by simple adjustmend settings a dynamic range of more than 10^4. The output frequency can vary from < 1 Hz up to > 1 MHz. So it is possible to use one sensor for measuring light both at day and night. As the output is TTL-level, you can connet the circuit directly to the PC's parallel (printer) port or the input ports of my psion organiser extension box. The measured frequencies are computed and stored in a standardized manner due to senitivity and output division settings. These values are stored in the downloadable CSV-files (accuracy +- 20%).
2) Temperature
Temperature reagistration was done by the circuit "LM 75" (National Semiconductors) for ground registration. Its resolution is 0.5 ° C. The more precise DS 1621 provided data at 4 m height.
The temperature can be read via a two wire line interface (I2C bus) directly and digitally by the PC or organiser.
3) Wind
The anemometer had three hemisperic shovels. Its rotation speed was registered by a light barrier with an accuracy of about 20 %.
All these sensors were mounted on a mast ca. 4 m above the ground.
Similar computer and organiser programs for cameras are found at:
© Dr. Wolfgang Strickling, Germany
back to my German Homepage
my shadow bands explanation page
My eclipse observations
1999, 2003, 2005
(in German), 2006, 2008, 2009, 2011 (DE), 2012
(DE), 2015 (DE),
2016, 2017
My eclipse projects
Tables with meteo values
im schatten. Avirtual exhibition of
my photos and texts of Adalbert Stifter (German language)
Bill
Ronald's eclipse page of Zimbabwe and his
temperature
measurement (nearly the same place as ours!)
My German eclipse Organiser page and technical documentation of the interface
(english)
last updated 2007-01-26
URL
http://www.strickling.net/2k1_engl.htm