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The Sun's Circle May Be Broken ....

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#1 SgrB2

SgrB2

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Posted 22 July 2021 - 12:09 PM

An ephemeris of the sun will give you the current diameter

of the sun in arcsec from the following site:

 

http://astropixels.c...un/sun2021.html

 

If you have an observation of the partial limb of the sun as

shown below, one can determine the diameter of the sun in

pixels by using three spaced points (A, B, & C) on the limb.  Knowing

both the diameter of the sun in arcsec and pixels allows the

plate scale to be found.  The positions of A, B, and C can be

determined in rectangular coordinates from a number of programs.

The linear algebra scilab is free and can be used to make the

computation whose output is seen below.  I've printed out a few

other things such as the nominal 0.5x focal reducer which is

really operating at 0.42x on these observations as well as

the f number of the system.

 

Cheers,

SgrB2

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  • Annotation 2021-07-22 123023.jpg
  • Circle for 2021-07-22.jpg

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