Confirm the classification and CMD position of V136_f

Confirm the classification and evolutionary status of V136_f by obtaining $I$-band data sufficient to determine its position in the color-magnitude diagram.

Background

V136_f is identified as a member according to Vasiliev (2021) and could be classified as a semiregular variable on the basis of its period. However, its VV magnitude places it below the tip of the red-giant branch, creating uncertainty about that classification. The authors retain it as a long-period variable provisionally and state that II-band observations are needed to resolve its position and classification.

References

Based on its period, it could be classified as an SR, but its magnitude in $V$ places it below the tip of the RGB. Data in $I$ are needed to confirm its position in the CMD and provide a more reliable classification; it has been decided to keep it as an LPV.

— 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 “SR and LPV stars”