P.E.I.S.D.
P.E.I.S.D: "If the observational error distribution of the star's positions
follows the normal distribution (which is a good approximation when many observations
are made), the probability that the actual position of the star is within the radius of the standard error of the indicated position is 68.3%. That means that if the Star's DecErr is given as 0.16", the star's actual declination should be within +/- 0.16" of the declination at the epoch calculated from the J2000 declination and proper motion provided in the catalog with the probability of 68.3%. Note that the term P.E.I.S.D. (e.g., Probable Error In Star's Declination) can be obtained by
multiplying the standard error by 0.6745 for the normal distribution since the
probable error means such that the probability within the probable error
is 50%."---Dr. Mitsuru Soma