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morphy_richards
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Re: Solar eclipse experiments

Thu Mar 12, 2015 1:50 pm

The cores were about 4 meters long and were kept upright by sticking them through a piece of board with a slightly over sized elliptical hole. You need to adjust the angle constantly as the sun travels with a speed of close to 1 degree per 15 minutes while the angular size of the sun is about 0.5 degrees.
I've been a bit worried about that, aiming the thing at the sun through a window which is incredibly awkward.
I get it about right by looking down the barrel right at the sun and aiming. And then waiting for the blue spots to disappear.

There has to be a better way!

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morphy_richards
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Re: Solar eclipse experiments

Fri Mar 13, 2015 12:15 pm

That was fun.
We now have some precision scientific apparatus: :) ;)
Image
And 7D and I will be hosting an eclipse party in our room from 8am until 8:50 when lesson one begins, then in lesson one we will commence the serious business of monitoring and analysis.

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morphy_richards
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Re: Solar eclipse experiments

Fri Mar 13, 2015 3:21 pm

Party! How cool?
Image

MikB
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Re: Solar eclipse experiments

Fri Mar 13, 2015 7:34 pm

morphy_richards wrote:
iming the thing at the sun through a window which is incredibly awkward.
I get it about right by looking down the barrel right at the sun and aiming. And then waiting for the blue spots to disappear.

There has to be a better way!
Better way: Aim it at the sun but look at the SHADOW it's casting for the smallest shadow. When it's perpendicular to the sun, the shadow will be smallest (this works with telescopes and binoculars quite well). Peering at the sun is not a great way :(

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morphy_richards
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Re: Solar eclipse experiments

Fri Mar 13, 2015 7:46 pm

Another good way is to stream the video from the web cam inside the pin hole camera, but the shadow method definately sounds good for pointing at the right general bit of sky first.

(I was wondering about attaching some thread to a support of some sort at the front of the barrel and the other end to the box at the back and attaching a card disc that could be moved up and down the thread. Start off with the disk near the back / close to eyes so it blocks up most of your field of view, aim approximately, move the disk further away down the thread and refine aim, repeat until eventually the disk is right near the front and you are perfectly aligned ... but, naaahhh, sod it ;) )

Something a bit strange seems to have started happening, sleep(1) in the python program seems to be longer than sleep (1), running the program today for quite a few minutes and we only had about 15 readings taken. Strangely enough that happened right after I decided for no good reason to overclock right up to turbo (it has been working perfectly fine on normal)

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Re: Solar eclipse experiments

Fri Mar 20, 2015 7:34 am

Have a few last minute adjustments to make before party starts... Didn't cycle, loaded down with OJ and croissants and the trains are running late. Arg!

Weather looks ... depressing :(

But there is a backup plan. :D

Mount webcam at front of.pinhole device instead of inside, science is now going to be to find correlation between samples and 'sky colour'.

Need to find a live feed of eclipse from somewhere with good weather and record time indexed images, computation activity - correct index for local time differences and compare with our data.

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Re: Solar eclipse experiments

Fri Mar 20, 2015 8:28 am

We have data, images and students!
(See a photo of heavy clouds and some data)
Attachments
2015-03-20-08-15-02.jpg
2015-03-20-08-15-02.jpg (5.42 KiB) Viewed 3914 times

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Re: Solar eclipse experiments

Fri Mar 20, 2015 9:53 am

I've got the graph of my temp/pressure data at https://plot.ly/~Dougie/280/_20th-mar-o ... ppressure/ I'll leave it running until 11:36.
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Re: Solar eclipse experiments

Fri Mar 20, 2015 10:03 am

light.png
light.png (17.52 KiB) Viewed 3881 times
Our light levels started out at about 805,
at 9:30 they dropped to 649
Currently they are 778 and rising.


Here is a snippet of data

1426839301.58,817
1426839302.93,816
1426839304.02,817
1426839305.02,817
1426839306.17,817
1426839307.4,816
1426839308.45,817
1426839309.84,817
1426839311.1,817
1426839312.14,817
1426839313.27,816
1426839314.44,817
1426839315.45,817
1426839316.49,817
1426839317.68,817
1426839318.73,817
1426839320.11,817
1426839321.21,817
1426839322.43,816
[...]
1426843697.27,648
1426843698.36,648
1426843699.4,648
1426843701.8,647
1426843703.13,647
1426843704.86,647
1426843706.54,647
1426843707.59,647
1426843709.66,647
1426843711.03,646
1426843712.53,646
1426843713.91,646
1426843715.52,646
1426843716.86,646
1426843719.45,646
1426843720.48,646
1426843721.81,646
1426843723.07,646
1426843724.2,646
1426843725.2,646
1426843726.76,645
1426843728.3,645
1426843730.37,645
1426843732.39,645
1426843733.84,645
1426843735.35,645
1426843736.95,645
1426843738.36,645
1426843739.68,645
1426843741.0,645
1426843742.35,645

When we plot using gnuplot like this:

Code: Select all

set datafile separator ","
plot datafile.csv using 0:1
But our charts just show straight lines
Last edited by morphy_richards on Fri Mar 20, 2015 10:09 am, edited 1 time in total.

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Re: Solar eclipse experiments

Fri Mar 20, 2015 10:04 am

DougieLawson wrote:I've got the graph of my temp/pressure data at https://plot.ly/~Dougie/280/_20th-mar-o ... ppressure/ I'll leave it running until 11:36.
I'll show that in a moment, thanks Dougie

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Re: Solar eclipse experiments

Fri Mar 20, 2015 10:06 am

Cool!

What's MSL?

mean sea level pressure?

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Re: Solar eclipse experiments

Fri Mar 20, 2015 10:19 am

morphy_richards wrote:Cool!

What's MSL?

mean sea level pressure?
Literally COOL as the temp dropped quite a bit through eclipse maximum.

QNH == mean sea level
QFE == pressure @ 110m ASL

I'll shutdown that RPi at 10:24 to avoid earlier data. There's only 500 data points in the dataset at plot.ly.

I'll see you in Tennessee in 2017 and in Luxor in 2027.
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Re: Solar eclipse experiments

Fri Mar 20, 2015 10:23 am

Here is our best view of maxima :)
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Re: Solar eclipse experiments

Fri Mar 20, 2015 10:24 am

DougieLawson wrote:
morphy_richards wrote: Literally COOL as the temp dropped quite a bit through eclipse maximum.
We all felt it here although our thermistor just registered 18 -> 17

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Re: Solar eclipse experiments

Fri Mar 20, 2015 10:34 am

morphy_richards wrote:
DougieLawson wrote:
morphy_richards wrote: Literally COOL as the temp dropped quite a bit through eclipse maximum.
We all felt it here although our thermistor just registered 18 -> 17
If you want the raw data, just ask. You can have a copy of the sqlite3 database or a CSV file (extracted from it).
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Re: Solar eclipse experiments

Fri Mar 20, 2015 10:40 am

Thanks again Dougie...

Feeling quite cross with (my inability to use) Gnuplot at the moment although we have plotted something more sensible with Libreoffice.

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Re: Solar eclipse experiments

Fri Mar 20, 2015 10:48 am

Completely mortified to share this but there is a bit on BBC School report about this too:
http://www.eastlea.newham.sch.uk/BBC

(Also, our kids did a really good interview with David Allen and a story on the BBC MicroBit here too)
Last edited by morphy_richards on Wed Mar 25, 2015 2:07 pm, edited 2 times in total.

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Re: Solar eclipse experiments

Fri Mar 20, 2015 11:21 am

Here is our data:

Light(quite interesting)

Temperature (not very interesting really)

Time is the first column and is the output of time.time() , literally the number of seconds since 1/1/1970

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Re: Solar eclipse experiments

Fri Mar 20, 2015 12:13 pm

Here a couple of plots, light units are arbitrary
Attachments
e-temp.png
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e-light.png
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Re: Solar eclipse experiments

Fri Mar 20, 2015 1:38 pm

I've fixed up my Plot.ly stuff (my normal indoor sensing got in the way).
The raw data from: 51° 14' 43", -001° 08' 01" is at: http://paste.debian.net/162245/
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Re: Solar eclipse experiments

Fri Mar 20, 2015 4:14 pm

I just watched a few highlights of the stargazing live eclipse show on I-player:

total eclipse (viewed from aircraft above faroe islands) @41 mins

Dave Akerman @30 mins (sadly no live cameras) @50 mins (describing the equipment). Balloon Cam footage wasn't able to make it onto the program.
Doug.
Building Management Systems Engineer.

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Re: Solar eclipse experiments

Wed Mar 25, 2015 11:58 am

I thought I'd mention that this topic (and the party poster!) made it into our blog post yesterday about Raspberry Pi eclipse observations: http://www.raspberrypi.org/pis-eye-view-eclipse/

I hope everyone enjoyed their eclipse viewings :-)

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Re: Solar eclipse experiments

Fri Mar 27, 2015 11:18 am

7D are delighted with their unexpected fame!

A nice piece of followup work here:
Image

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