There is an example of the left-right consistency check of three possible
parallaxes in a pixel in that figure.
His reluctance to publish may have been due to a fear of being proved wrong--several other astronomers had in recent years 'found' parallaxes that had been shown to be non-existent--and he would not have wished to look foolish.
Quite a few other observers over the following decades attempted to get parallaxes of Proxima but the results concerning its true proximity often seemed marginal or contradictory.
5-(a), (b) and (c), blue lines and red lines represent the maximum and minimum
parallaxes which are comfortable for viewing, respectively.
TAU would be able to measure
parallaxes of all the stars in our galaxy (distances to more than 30,000 parsecs or 100,000 light-years) and of other nearby galaxies--the Magellanic clouds, the local group galaxies--to approximately a ten-millionth of a second.
Multiple iterations of this process will converge on the individual
parallaxes of Venus and the Sun.
Some measurements --brightnesses and positions though not
parallaxes --were even made of a million stars, later enlarged to 2.5 million stars, at a much lower positional accuracy.
Gaia is the first great leap in the measurement of stellar positions, proper motions, and
parallaxesBut their example regarding the first measurement of stellar parallax might inadvertently leave readers with the impression that Friedrich Bessel, who measured the parallax of 61 Cygni in 1838, was scooped by both Thomas Henderson and Wilhelm Struve, who had previously measured the
parallaxes of Alpha Centauri and Vega, respectively.
With L A unprecedented accuracy, the space craft measured the positions, motions, and
parallaxes (distances) of 118,000 stars.
It measured the
parallaxes of 118,218 bright stars to the extraordinary precision of about 1 milliarcsecond.
Even though he spent the remainder of his long career measuring the precise positions of stars, their
parallaxes remained beyond his grasp.
The spacecraft made headlines last year when Michael Feast (University of Cape Town, South Africa) and his colleagues used it to measure the
parallaxes of Cepheid variable stars.
The principal result of Hipparcos was to provide parallax measurements (the change in position of nearby stars against background ones) for all the brightest stars to a precision as good as the best ground-based
parallaxes. Astronomers now have the most accurate positional and photometric data--which also include proper motion and color information--to date for up to one million stars as faint as magnitude 12.5.
With this reasoning, Henry and his collaborators seek
parallaxes for high-proper-motion stars whose magnitudes and colors further imply closeness.
