17th January 2010
M42 Nebula in Orion
10" Newtonian, Canon 350D, 77*30 seconds
The ten inch scope was used. Compare with image from
January 2009 using the six
inch.
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Different processing |
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29th January 2010
Mars near opposition
John Clarke suggested on the SPA website that it would be interesting to
image Mars during its 2010 close encounter, from different locations on the
Earth. Parallax would enable a calculation to be made of how far away Mars was
at the time. Some images are on his website
here.
I managed to get
some images on the 29th, 30th and 31st. Below is a composite of several images,
superimposed on a DSS sky map.
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The weather was not
kind to us. Very seldom did clear skies exist simultaneously at the various
observing sites. However on the 31st, Kos Coronaios in South Africa
(Louis Trichardt) had clear skies and so did the UK.
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An image from
Kos
One problem is that Mars is so bright that any shots
long enough to get any background stars will have Mars very much over-exposed.
My technique was to draw a circle over Mars and then find the
centre.
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My reflector produces long
diffraction spikes on Mars. The intersection should give a fairly accurate
location for the centre of the
planet.
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Kos took two images at times on
either side of my image. Mars was moving across the sky at a fairly linear pace
so it was possible to extrapolate (the blue dot) a position where Mars would
have been at 10pm. My position is the red dot.
The distance between
red and blue dots equates to 19.9 arcseconds. The
distance between Kos and me was 8202km (straight line through the
Earth). Making the assumption that this baseline is perpendicular to the line
to Mars gives a distance of 84,858,612km. The software
Cartes du Ciel gave a value of
99,617,222km. This is an error of 14.8%.
Not quite up to
NASA standards but a fun exercise!
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On the 5th
February the process was repeated. This time images were almost simultaneous,
at 7pm GMT. The distance to Mars came out as 125,402,168km. Cartes du
Ciel gave a value of 100,694,414km. Our average over the two days =
105,130,390km. Cartes du Ciel average = 100,155,818km |
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Oleg Toumilovitch in
Johannesburg took two images at 6:15 and 7:15 on the 31st. Extrapolating (green
dot) showed where Mars would be at the time of my image at 10pm (red
dot).
The parallax was 26.012 arcseconds. A baseline of 8393.7km gives a
distance to Mars of 66,558,529km.
This is quite a large error,
undoubtedly due to errors in the extrapolation process. |
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An image of Mars, taken by Oleg on
January 27th when Mars was at its closest to
Earth.
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