Help calculate the yield of this nuclear device

[Orionblamblam]

I used to have an Excel spreadsheet that did a nifty thing: you'd paste in an image... say, a scan of an old graph... and then pick out specific points on that graph. You'd pick out points on the line, and known values of the X and Y axes. Linear or log, whatever, even if the graph was warped or rotated, it'd figure out what the values were and rebuild the graph as a regular Excel graph. It was a great way to back data points out of ancient printed data. Alas, that spreadsheet disappeared with my employment.

Here's a graph that I'd love to back a single value out of.... the yield "X" of the 1963 design study. Were the Y axis linear, it'd be easy, but it's logarithmic, and that makes it more difficult. Anybody able and willing to help? Anybody have an Excel spreasheet that does what I mentioned?

 

[Michel Van]

for Excel spreasheet, sorry no

i have only this:
http://www.projectrho.com/rocket/rocket3x.html#nuke
http://www.5596.org/cgi-bin/nuke.php

 

[Jemiba]

If it's just the single value, I would go like this .

The linear scale must give the value 1 for the log value 10 and 2 for 100,
as those are the exponents to the basis 10. And your graph does exactly that.
Measuring the linear value for the wanted yield gives 1,46, which as exponent
to the basis 10 would give a yield of 28,8 kT.

I hope, my thoughts are understandable, as errors are only recognisable then and
I'm not absolutely sure ... :

 

[red admiral]

As Jemiba

Measure the distance between 10 and 100 and 10 and the red line. Divide one by the other so the red line is around 47% of the distance in between. Then inverse log to give estimated yield of 29.4kT which is close enough to Jemiba's estimate given the thickness of the lines.