AAVSO: American Association of Variable Star Observers

CCD Photometry, Light Curve Modeling, and Period Study of GSC 2624-0941, a Totally Eclipsing Overcontact Binary System

Volume 49 number 2 (2021)

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Kevin B. Alton
UnderOak Observatory, 70 Summit Avenue, Cedar Knolls, NJ 07927; kbalton@optonline.net
John C. Downing
La Ventana Observatory, 28881 Sunset Road, Valley Center, CA 92082; johndowning2014@outlook.com

Abstract

Precise time-series multi-color (BVRc or Ic) light curve (LC) data were acquired from GSC 2624-0941 (= NSVS 8114939 = 2MASS J18275502+3148337) at three different sites between 2018 and 2021. New times of minimum (ToM) from data acquired during this study along with other ToMs extrapolated from the SuperWASP survey were used to generate an updated linear ephemeris. Secular analyses (ToM differences vs. epoch) revealed changes in the orbital period of GSC 2624-0941 over the past 17 years suggesting an apparent increase in the orbital period based on a parabolic fit of the residuals. Simultaneous modeling of multi-color LC data was accomplished using the Wilson-Devinney code. Since a total eclipse is observed, a photometrically derived value for the mass ratio (qptm) with acceptable uncertainty could be determined which subsequently provided estimates for some physical and geometric elements of GSC 2624-0941.