Johann Friedrich Julius Schmidt estimating it as 3 to 4 arcmin across on March 9, and 8 to 10 arcmin across on the 22nd of that same month.
It is especially popular with shooters familiar with the Imperial measurement system because 1 MOA subtends approximately one inch at 100 yards, a traditional distance on target ranges.
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The exact distance varies along meridians because the shape of the Earth is slightly oblate.
The main scientific goal of the mission is the study of astronomical objects with an angular resolution up to a few millionths of an arcsecond.
Joan of Arc | Minute Maid | Arc de Triomphe | L'Arc-en-Ciel | Up to the Minute | ARC | The Passion of Joan of Arc | story arc | Just a Minute | Ten Minute Rule | Revolutions per minute | Prix de l'Arc de Triomphe | Fort Jeanne d'Arc | Joan of Arc (1948 film) | Arc of Infinity | Arc lamp | Stronger Every Minute | Arc Angels | Single-Minute Exchange of Die | Royal Saltworks at Arc-et-Senans | One Minute Please | Minute to Win It | Minute of arc | Minute Maid Park | Jeanne d'Arc | Courageous Cat and Minute Mouse | arc lamp | ARC International | 3-Minute Warning | words per minute |
The best conditions give a seeing disk diameter of ~0.4 arcseconds and are found at high-altitude observatories on small islands such as Mauna Kea or La Palma.
In 1864 D'Arrest made an unsuccessful search for Martian satellites, and posited an upper limit of 70 minutes of arc as the distance from Mars within which a moon should be sought.