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Re: Testing sextant arc error
From: Bill Lionheart
Date: 2017 Jan 20, 14:06 +0000
From: Bill Lionheart
Date: 2017 Jan 20, 14:06 +0000
Greg
I should have been clearer. Laser reflected only off center of index mirror so no parallax. This is just to calibrate the arc.
If instead you put the laser in place of the sight tube you need to calculate parallax. My laser is on the wall at zero of the ruler.
Bill
On 20 Jan 2017 2:00 p.m., "Greg Rudzinski" <NoReply_Rudzinski@fer3.com> wrote:
Bill,
Sextant mirror parallax needs to be accounted for if done this way.
Greg Rudzinski
From: Bill Lionheart
Date: 2017 Jan 20, 08:12 +0000Suppose you got a 30m room and a ruler calibrared in mm at one end. Then point a well collimated laser from one end of the ruler to the mirror on the sextant (horizontal on a table) so reflected a spot on the ruler. 1mm would be approx 0.1 minute. Take the average either side of the dot and use arc tan on your calculator. Depending on the length of the ruler do the full arc in several stages.Would that work?Bill
