Abstract
Hunter and Lü1 claim that on June 11, 1969 (UT), the quasi-stellar source 3C 345 showed a variation of ≈0.4 blue magnitudes within the span of a few hours. The first ten of their observations on this night (shown in Fig. 3 of their article) have a range of only 0.19 mag, while the inclusion of their eleventh and last observation increases the range to 0.38 mag. If ten observations have a range of 0.19 mag, then the expected r.m.s. deviation of a single observation (σ) is ±0.062 mag and the expected probable error of a single observation is ±0.042 mag (ref. 2, Table 6). Because Hunter arid Lü give probable errors in the range ±0.02 to ±0.055 for their ten observations, it would seem that these ten observations give little or no evidence for any real variation in the object. The reality of the alleged variation therefore depends entirely on the reliability of their last observation on that night.
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References
Hunter, J. H., and Lü, P. K., Nature, 223, 1045 (1969).
Lindley, D. V., and Miller, J. C. P., Cambridge Elementary Statistical Tables, 7 (Cambridge, 1953).
Kinman, T. D., Lamla, E., Ciurla, T., Harlan, E., and Wirtanen, C. A., Astrophys. J., 152, 357 (1968).
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KINMAN, T. Optical Variations in 3C 345. Nature 224, 565 (1969). https://doi.org/10.1038/224565a0
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DOI: https://doi.org/10.1038/224565a0
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