摘要：The paper “Estimating the parameters of globular cluster M 30
(NGC 7099) from time-series photometry”, used an incorrect
expression for the phase φ(t) at time t of a periodic variable
undergoing a linear period change. Equation (3) of that paper
should be:
φ(t) = N E (t) − ?N E (t)?, (1)
where N E (t) is the number of cycles elapsed at time t since a ref-
erence epoch E. For a constant rate of period change β, N E (t) is
given by (Kains et al. 2015):
N E (t) =
1
β
ln
?
1 +
β
P 0
(t − E)
?
, (2)
where P 0 is the period at the epoch E. Using this correct expres-
sion, we are still unable to phase the light curve of RR Lyrae
star V16 satisfactorily, and our conclusions therefore remain
unaffected.
