Astronomy in Focus, XXIXB, Focus Meeting 17 XXIXth IAU General Assembly, August 2015 Piero Benvenuti, ed. c  International Astronomical Union 2016 doi:10.1017/S1743921316006074 Light curve modeling of the short-period W UMa star GSC 02049-01164 Lester Fox-Machado 1 , Juan Echevarria 2 , Diego Gonz´ alez-Buitrago 2 and Raul Michel 1 1 Instituto de Astronom´ ıa, Universidad Nacional Aut´ onoma de M´ exico, Ap. P. 877, Ensenada, BC 22860, M´ exico email: lfox@astro.unam.mx 2 Instituto de Astronom´ ıa, Universidad Nacional Aut´ onoma de M´ exico, Ap. P. 70-264, M´ exico, D.F. 04510, Mexico Abstract. The preliminary results of an analysis of the time-series photometric data of binary star GSC 02049-01164 (ROTSE1 J164341.65+251748.1) are presented. GSC 02049-01164 was observed for eight consecutive nights with the 0.84-m telescope of the San Pedro Martir Ob- servatory in Mexico. The light curve of GSC 02049-01164 is typical of those of W UMa type binary stars. In an effort to gain a better understanding of the binary system and determine its physical properties we have analyzed the light curve with the software PHOEBE V.0 0.31a. We have found that GSC 02049-01164 binary system has a mass ratio of ∼ 0.42, an inclination of ∼ 85 degrees, a semi-major axis of ∼ 2.24 R ⊙. It is likely that the two stellar components are in contact, with a degree of overcontact of 13 %. The physical parameters of the stellar components have been derived. Keywords. binaries: eclipsing, stars: individual (GSC 02049-01164) 1. Introduction GSC 02049-01164 (=ROTSE1 J164341.65+251748.1) was reported as a new eclipsing binary star by Zissell (1997) after monitoring three comparison stars suspected variables in the field near the dwarf nova AH Her. He reported a period of 0.323460 days and V band light curve amplitude of 0.6 mag. GSC 02049-01164 was also observed by the robotic optical transient search experiment 1 (ROTSE-1) CCD survey (Akerlof et al. 2000) who reported a period of 0.323432 days. Since them no new observations of the star have been reported. Recently during a long-term monitoring of AH-Her we observed GSC 02049-01164 for eight nights. Since the resulting light curve is longer and better sampled than those obtained in previous studies, we have computed a binary star model to derive the most important parameters of the binary system and its components. A preliminary analysis of these observations is given in the present paper. 2. Photometric observations The CCD observations have been made with the 0.84-m f/15 Ritchey-Chr´ etien tele- scope at Observatorio Astron´omico Nacional at Sierra San Pedro M´ artir (OAN-SPM), during eight consecutive nights from 2013, May 31 to June 7. More data from four observ- ing nights were obtained in August 2013. The telescope hosted the filter-wheel ‘Mexman’ with a CCD camera, which has a 2048 × 2048 pixels array, with a pixel size of 15 × 15 μm 2 . The gain and readout noise of the CCD camera are 1.8 e − /ADU and 7.0 e − , respectively. The typical field of view in this configuration is about 9 ′ × 9 ′ arcmin 2 with the scale of 0. 28 ′′ /pixel. 536 https://www.cambridge.org/core/terms. https://doi.org/10.1017/S1743921316006074 Downloaded from https://www.cambridge.org/core. IP address: 54.70.40.11, on 13 Apr 2019 at 09:25:29, subject to the Cambridge Core terms of use, available at