hi guys and gals
for those interested in solar observations and imaging, I have found a very useful tool for determining the size of
features on the sun eg. sunspots, filaments and prominences etc
I present the Solar Ruler, available here ...
https://samuelastronomy.wordpress.com/tag/solar-ruler/
there is an English version here ...
http://thesolarexplorer.net/index.php/tutorial/article2/article2/the-solar-ruler
the download link is right at the bottom of the page
This is a PDF file that you load into your fav image processing program that is able to support the manipulation of layers when combined
For me, I use Photoshop (PS). I load in my solar image and I load in this PDF file they are in separate tabs at the top of the image viewing area
I resize the solar ruler image to equal the size of my solar image as close as possible, then I copy it and paste it over the top of the solar image.
I then use the move function to move the solar ruler image around so I can align it with the solar image to produce this result
Solar image is the first image from my previous post ...
NOTE: the image is seriously reduced in size and quality to be able to post on this forum
You can see I managed to get the solar and ruler image sizes to match reasonably well
I can now quickly determine the approx. size of that big prominence ... ~ 60,000 - 65,000 km in height above the suns disk !
Quite impressive
hope some finds this useful
Dave