[RadioAstronomer]

Thank you both. I was busy inserting figures into a paper I am writing last night.

[RightWingAtheist]

Remember to include them in the "special thanks"! :-)

[longshadow]

After some Googling it seems Friedrich Bessel made the first parallax measurment two years before John Draper made the first daguerreotype image of the Moon. Modern measurment are done with photography and spectroscopy, but it seems the pioneering work was done with sextants.

I admit to not being up to speed on this issue, but it seems to me all that would be needed to do parallax measurements would be an adjustable micrometer eyepiece and a telescope of sufficient resolution (large enough apeture and good enough optical quality).

Measure the angular separation between the desired two stars, wait several months to create a large enough baseline, and measure again. Repeat on successive years to be sure the change in separation isn't due to proper motion, then compute the distance trigonometrically.

What I don't know is when micrometer eyepiece was invented, or what it's limits of accuracy were, but in theory at least, parallax could be measured without the need for photographic imaging.

[forsnax5]

"...a paper I am writing last night."

There was a young lady named Bright,
Who transcribed much faster than light,
She'd write it all day,
In a relative way,
And have it the previous night.

:)