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    Re: Sun sights during an eclipse: "bad limb" calculation
    From: Frank Reed
    Date: 2023 Oct 4, 18:26 -0700

    Lars Bergman, you wrote:
    "My current result: Sun's LL covered by moon between 17h07m56s and 18h20m48s UT."

    Sounds good to me. I have not made any attempt at real calculations. Instead I simulated the eclipse in Stellarium recording the times when the azimuth of the edge of the "bite" taken out of the lower limb matched the Sun's azimuth. The Sun's azimuth at any instant can be read directly if those coordinates are selected as one of the standard display options. Set the time, click on the Sun, read off the azimuth. The edge of the bite is trickier since it's not a clickable object in Stellarium. Instead, there's a pointer tool in Stellarium that will display the coordinates of the mouse pointer in altitude and azimuth if it's configured properly. I align that (very carefully!) with edge of the bite and record the azimuth. I did this once every thirty seconds for the period of interest. Then I ran a line through the points and calculated the time when the azimuths matched. I get 17h07m44s and 18h20m36s. 

    Both of the times that I find by simulation in Stellarium are earlier than your calculated times, Lars, by 12 seconds. Are these significant differences? That I don't know. The duration is identical, which is reassuring. The Lower Limb of the Sun is defective, a "bad limb", for 1 hour 12 minutes and 52 seconds from the given location during this eclipse.

    Frank Reed

       
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