Majaess, DanielBonatto, Charles J.Turner, David GSaito, Roberto KMinniti, DanteMoni Bidin, ChristianGonzález-Díaz, DaniloAlonso-Garcia, JavierBono, GiuseppeBraga, Vittorio F.Navarro, Maria GCarraro, Giovanni2025-04-162025-04-1600250004637Xhttps://repositorio.unab.cl/handle/ria/64210INDEXACION SCOPUSPre-Gaia distances for the open cluster Pismis 19 disagree with Gaia parallaxes. A Two Micron All Sky Survey (2MASS) JKs red clump distance was therefore established for Pismis 19 (2.90 ± 0.15 kpc), which reaffirms that zero-point corrections for Gaia are required. OGLE GD-CEP-1864 is confirmed as a member of Pismis 19 on the basis of DR3 proper motions and its 2MASS+Vista Variables in the Vía Láctea color-magnitude position near the tip of the turnoff. That 0.3 day variable star is likely a δ Scuti rather than a classical Cepheid. The case revealed a pertinent criterion to segregate those two populations in tandem with the break in the Wesenheit Leavitt Law (≃0.5 day). Just shortward of that period discontinuity are δ Scutis, whereas beyond the break lie first overtone classical Cepheids mostly observed beyond the first crossing of the instability strip. © 2025. The Author(s). Published by the American Astronomical Society.enArtículo