A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Modris Fersters
Date: 2023 May 18, 12:13 -0700
I am glad that you managed to find Venus. Today I took Venus daylight sights too. I tried both:
1) to measure the distance between the Sun and Venus;
2) to measure the altitude of Venus.
The first task was very easy. Some days ago I looked in Stellarium that the distance between Venus and Sun is about 45 degrees. I preset sextant to that angle, put shades on horizon mirror and looked at Sun. Slowly rotating sextant along telescope axis I found Venus very easily. Then I adjust micrometer.
On Second task I was experementing with optimal method to find Venus in horizon mirror. The best method for me was following: I preset sextant to actual distance angle. Then put shades on index mirror. With sextant oriented vertically I looked in the direction of the Sun, but telescope oriented about 45 degrees (this is the angle of Venus/Sun distance) downward from the Sun untill I found the reflection of the Sun in telescope field of view. It is easy. If, for example, the altitude of the Sun is about 45 degrees, I should direct telecope horizontaly. If altitude of the Sun is about 30 degrees, I should direct telescope about 15 degrees below horizon to get Sun image in the telescope.
Then I rotated sextant and at the same time moved it upward, keeping the Sun in the field of view until I found Venus. Then I rotated sextant along telescope axis until the instrument was vertically oriented. Then I removed index shades and, looking at Venus, moved index arm to 0 degrees. At that moment I could see two images of Venus. Next step was bringing Venus down to the horizon to measure the altitude.
I will add that I could not sea Venus without telescope (7X magnification).
You wrote that you took the sights near sunset. I was able to take these sights close to the noon. But your choice near sunset is better.
I will calculate the actual distance between Sun and Venus with your Lunar4.4. to test my sextant.
Thank you for sharing your experience!