> Metrology > Refraction and Sightline > arghXiv:2603.11904
Variation in the Cited Refraction Coefficient with the Result Required
Abstract: The coefficient of terrestrial refraction is a measurable property of the air along a sightline and varies, in the conditions under which these observations are taken, between roughly 0.05 and 0.30. We collected 388 instances in which a value was cited in support of a conclusion about a disputed observation, and recorded the value alongside the conclusion it was cited for. The distribution is bimodal. Values cited in support of the conclusion that an observation shows obscuration cluster at 0.08; values cited in support of the conclusion that it does not cluster at 0.26. Cited values were accompanied by a measurement of the conditions in 4 of the 388 cases. We note that both clusters lie within the physical range, and that this is what makes the practice durable.