Confirm period change in RRc star KT-36

Confirm whether the RRc star KT-36 exhibits a period change by constructing and analyzing an observed-minus-calculated (O-C) diagram.

Background

The light curves of KT-36 show an offset between filters, and no single period adequately fits all available data. The authors therefore consider a period change likely but state that an O-C diagram is needed for confirmation. Establishing whether the period has changed would clarify the star’s pulsation behavior and improve the interpretation of its Fourier analysis.

References

There is an offset between its filters, and no period could be found that simultaneously fitted all the data. The star likely shows evidence of a period change over time; an $O-C$ diagram would be needed to confirm this.

— A Homogenized Catalogue of Variable Stars in the Globular Cluster M22: Membership, Physical Parameters, and Distance  (2609.11850 - Yepez et al., 10 Sep 2026) in Appendix, Section “Comments about individual stars,” subsection “RR Lyrae stars”