  We wonder whether M\"arzke-Wheeler effects influence on measured data in
nature. Through a formula developed in this letter for the calculation of the
M\"arzke-Wheeler map of a general accelerated observer, we study the influence
of the M\"arzke-Wheeler acceleration effect on the NASA's Pioneer anomaly and
found that it is about a fifth of the anomaly value. Due to statistical errors
in the measured anomaly, it is not possible to neither confirm nor neglect the
influence of the M\"arzke-Wheeler acceleration effect on the measured Pioneer
data. We hope that the ideas presented here could encourage other research
teams in the search for other observational objects that could finally answer
the question posed in this letter.
