Transit Timing Analysis and Parameter Refinement of the Qatar-1 System

Abstract

In this study, new ground-based transit photometry for Qatar-1b, obtained with the 1.0 m TUG100 telescope in Türkiye, is presented alongside high-precision space-based data from the TESS mission. Using EXOFASTv2, we performed a global MCMC fitting of the light curves to update the physical and orbital configuration of the system. Our results remain consistent with previously published stellar and planetary parameters. To investigate the orbital period variations of the system, we combined our new transit timings with historical and TESS data, allowing us to update the orbital period. An evaluation of the extended O–C diagram suggests that a linear ephemeris is sufficient, as we find no significant evidence (ΔBIC = 5.86) for long-term orbital period variations such as orbital decay. Additionally, probing the frequency analysis with both the Lomb-Scargle periodogram and the Weighted Wavelet Z-transform (WWZ) confirmed the absence of any prominent periodic variations.

Keywords

• Exoplanets
• Hot Jupiters
• Transit photometry
• Transit timing variation

References

1. Alsubai, K. A., Parley, N. R., Bramich, D. M., West, R. G., Sorensen, P. M., Collier Cameron, A., Latham, D. W., Horne, K., Anderson, D. R., Bakos, G. Á., Brown, D. J. A., Miller, G. R. M., Pollacco, D., Queloz, D., Smalley, B., Triaud, A. H. M. J., Udry, S., & Szentgyorgyi, A. (2011). Qatar-1b: A hot Jupiter orbiting a metal-rich K dwarf star. Monthly Notices of the Royal Astronomical Society, 417(1), 709–716. https://doi.org/10.1111/j.1365-2966.2011.19316.x
2. Astropy Collaboration. (2013). Astropy: A community Python package for astronomy. Astronomy & Astrophysics, 558, Article A33. https://doi.org/10.1051/0004-6361/201322068
3. Bakos, G. Á., Pál, A., Torres, G., Sipőcz, B., Latham, D. W., Noyes, R. W., Mazeh, T., Hartman, J. D., Kovács, G., Fischer, D. A., Howard, A. W., Marcy, G. W., Johnson, J. A., Esquerdo, G. A., Miller, R. P., Fűrész, G., Sasselov, D. D., Stefanik, R. P., Shporer, A., ... Sári, P. (2009). HAT-P-10b: A light and moderately hot Jupiter transiting a K dwarf. The Astrophysical Journal, 696(2), 1950–1955. https://doi.org/10.1088/0004-637X/696/2/1950
4. Baluev, R. V., Sokov, E. N., Jones, H. R. A., Shaidulin, V. S., Sokova, I. A., Nielsen, L. D., Benni, P., Shadick, S., Errmann, R., Panchal, A., Rajput, S., & Karimov, R. G. (2019). Homogeneously derived transit timings for 17 exoplanets and reassessed TTV trends for WASP-12 and WASP-4. Monthly Notices of the Royal Astronomical Society, 490(1), 1294–1312. https://doi.org/10.1093/mnras/stz2620
5. Cardoso, J. V. D. M., Hedges, C., Gully-Santiago, M., Saunders, N., Cody, A. M., Barclay, T., Hall, O., Sagear, S., Turtelboom, E., Zhang, J., Williams, A., Barentsen, G., & Lightkurve Collaboration. (2018). Lightkurve: Kepler and TESS time series analysis in Python (ascl:1812.013) [Software]. Astrophysics Source Code Library.
6. Collins, K. A., Kielkopf, J. F., & Stassun, K. G. (2017a). Transit timing variation measurements of WASP-12b and Qatar-1b: No evidence of additional planets. The Astronomical Journal, 153(2), Article 78. https://doi.org/10.3847/1538-3881/153/2/78
7. Collins, K. A., Kielkopf, J. F., Stassun, K. G., & Hessman, F. V. (2017b). AstroImageJ: Image processing and photometric extraction for ultra-precise astronomical light curves. The Astronomical Journal, 153(2), Article 77. https://doi.org/10.3847/1538-3881/153/2/77
8. Covino, E., Esposito, M., Barbieri, M., Mancini, L., Nascimbeni, V., Claudi, R., Desidera, S., Gratton, R., Lanza, A. F., Sozzetti, A., Biazzo, K., Affer, L., Gandolfi, D., Munari, U., Pagano, I., Bonomo, A. S., Collier Cameron, A., Hébrard, G., Maggio, A., ... Turrini, D. (2013). The GAPS programme with HARPS-N at TNG: I. Observations of the Rossiter-McLaughlin effect and characterisation of the transiting system Qatar-1. Astronomy & Astrophysics, 554, Article A28. https://doi.org/10.1051/0004-6361/201321298

9. Cowan, N. B., & Agol, E. (2011). The statistics of albedo and heat recirculation on hot exoplanets. The Astrophysical Journal, 729(1), Article 54. https://doi.org/10.1088/0004-637X/729/1/54
10. Eastman, J. D., Rodriguez, J. E., Agol, E., Stassun, K. G., Beatty, T. G., Vanderburg, A., Gaudi, B. S., Collins, K. A., & Luger, R. (2019). EXOFASTv2: A public, generalized, publication-quality exoplanet modeling code. arXiv. https://doi.org/10.48550/arXiv.1907.09480
11. Er, H., Ozdonmez, A., Kenger, M. E., Gurbulak, B. B., Nasiroglu, I., Tekkesinoglu, M., & Karaman, N. (2025). Investigating the system configuration of Kepler-451 through orbital period variations: Dynamical and magnetic interpretations. The Astrophysical Journal, 994(1), Article 67. https://doi.org/10.3847/1538-4357/ae1029
12. Er, H., Ozdonmez, A., Kenger, M. E., Tekkesinoglu, M., & Ege, E. (2026). Study of orbital period variation in DK Cyg using extended eclipse timing data. Advances in Space Research, 77, 1365–1371. https://doi.org/10.1016/j.asr.2025.10.029
13. Foster, G. (1996). Wavelets for period analysis of unevenly sampled time series. The Astronomical Journal, 112(4), 1709–1729. https://doi.org/10.1086/118137
14. He, Y., Wu, D. H., & Jin, S. (2024). Dynamical instabilities in post-disc evolution: Hot Jupiters left isolated. Monthly Notices of the Royal Astronomical Society, 530(4), 3934–3941. https://doi.org/10.1093/mnras/stae1076
15. Hord, B. J., Colón, K. D., Kostov, V., Galgano, B., Ricker, G. R., Vanderspek, R., Latham, D. W., Seager, S., Winn, J. N., Jenkins, J. M., Berardo, D., Huang, C. X., Quinn, S. N., Rose, M. E., Smith, J. C., & Wohler, B. (2021). A uniform search for nearby planetary companions to hot Jupiters in TESS data reveals hot Jupiters are still lonely. The Astronomical Journal, 162(6), Article 263. https://doi.org/10.3847/1538-3881/ac2602
16. Komacek, T. D., & Showman, A. P. (2016). Atmospheric circulation of hot Jupiters: Dayside–nightside temperature differences. The Astrophysical Journal, 821(1), Article 16. https://doi.org/10.3847/0004-637X/821/1/16
17. Kreidberg, L. (2015). Batman: Basic transit model calculation in Python. Publications of the Astronomical Society of the Pacific, 127(957), 1161–1165. https://doi.org/10.1086/683602
18. Kutluay, A. C., Baştürk, Ö., Barker, A. J., Yalçınkaya, S., Southworth, J., Selam, S. O., Esmer, E. M., Aksu, O., & Hajarat, S. (2026). Chasing the tides: Searching for orbital decay signatures in transit timing data and tidal models for 20 hot Jupiters. Publications of the Astronomical Society of the Pacific, 138(2), Article 024405. https://doi.org/10.1088/1538-3873/ae406a
19. Lomb, N. R. (1976). Least-squares frequency analysis of unequally spaced data. Astrophysics and Space Science, 39(2), 447–462. https://doi.org/10.1007/BF00648343
20. Maciejewski, G., Dimitrov, D., Neuhäuser, R., Tetzlaff, N., Niedzielski, A., Raetz, S., Adam, C., Roell, T., & Mugrauer, M. (2011). Transit timing variation and activity in the WASP-10 planetary system. Monthly Notices of the Royal Astronomical Society, 411(2), 1204–1212. https://doi.org/10.1111/j.1365-2966.2010.17753.x
21. Maciejewski, G., Fernández, M., Aceituno, F. J., Ohlert, J., Puchalski, D., Dimitrov, D., Seeliger, M., & Neuhäuser, R. (2015). No variations in transit times for Qatar-1 b. Astronomy & Astrophysics, 577, Article A109. https://doi.org/10.1051/0004-6361/201526031
22. Maciejewski, G., Fernández, M., Aceituno, F., Ramos, J. L., Dimitrov, D., Donchev, Z., & Ohlert, J. (2021). Revisiting TrES-5 b: Departure from a linear ephemeris instead of short-period transit timing variation. Astronomy & Astrophysics, 656, Article A88. https://doi.org/10.1051/0004-6361/202142424
23. Maciejewski, G., Fernández, M., Sota, A., Amado, P. J., Ohlert, J., Bischoff, R., Neuhäuser, R., & Sicilia, J. A. (2023). Search for planets in hot Jupiter systems with multi-sector TESS photometry. III. A study of ten systems enhanced with new ground-based photometry. arXiv. https://doi.org/10.48550/arXiv.2307.00538
24. Mancini, L., Southworth, J., Raia, G., Tregloan-Reed, J., Mollière, P., Bozza, V., Lanza, A. F., & Wertz, O. (2017). Orbital alignment and star-spot properties in the WASP-52 planetary system. Monthly Notices of the Royal Astronomical Society, 465(1), 843–857. https://doi.org/10.1093/mnras/stw1987
25. Mandel, K., & Agol, E. (2002). Analytic light curves for planetary transit searches. The Astrophysical Journal Letters, 580(2), L171–L175. https://doi.org/10.1086/345520
26. Mannaday, V. K., Thakur, P., Jiang, I. G., Sahu, D. K., Joshi, Y. C., Pandey, A. K., Joshi, S., Griv, E., Mkrtichian, D. E., & Püsküllü, Ç. (2020). Probing transit timing variation and its possible origin with 12 new transits of TrES-3b. The Astronomical Journal, 160(1), Article 47. https://doi.org/10.3847/1538-3881/ab9818
27. Mannaday, V. K., Thakur, P., Southworth, J., Jiang, I. G., Sahu, D. K., Mancini, L., Vaňko, M., Kundra, E., Pribulla, T., Joshi, Y. C., Pandey, A. K., Griv, E., Mkrtichian, D. E., & Shlyapnikov, A. (2022). Revisiting the transit timing variations in the TrES-3 and Qatar-1 systems with TESS data. The Astronomical Journal, 164(5), Article 198. https://doi.org/10.3847/1538-3881/ac91c2
28. MAST Portal. (2026, 26 Şubat). Space Telescope Science Institute. https://mast.stsci.edu/
29. Matsumura, S., Peale, S. J., & Rasio, F. A. (2010). Tidal evolution of close-in planets. The Astrophysical Journal, 725(2), 1995–2016. https://doi.org/10.1088/0004-637X/725/2/1995
30. Mayor, M., & Queloz, D. (1995). A Jupiter-mass companion to a solar-type star. Nature, 378(6555), 355–359. https://doi.org/10.1038/378355a0
31. Mislis, D., Mancini, L., Tregloan-Reed, J., Ciceri, S., Southworth, J., D'Ago, G., Bruni, I., Baştürk, Ö., Alsubai, K. A., Bachelet, E., D'Alessandro, R., Murgas, F., Pallé, E., Parley, N., Rai, J. P., Rostron, J. W., Southworth, J., Tregloan-Reed, J., & Schroeder, T. (2015). High-precision multiband time series photometry of exoplanets Qatar-1b and TrES-5b. Monthly Notices of the Royal Astronomical Society, 448(3), 2617–2623. https://doi.org/10.1093/mnras/stv197
32. NASA Exoplanet Archive. (2026, 26 Şubat). California Institute of Technology. https://exoplanetarchive.ipac.caltech.edu/index.html
33. Parmentier, V., Showman, A. P., & Fortney, J. J. (2021). The cloudy shape of hot Jupiter thermal phase curves. Monthly Notices of the Royal Astronomical Society, 501(1), 78–108. https://doi.org/10.1093/mnras/staa3418
34. Patra, K. C., Winn, J. N., Holman, M. J., Gillon, M., Burdanov, A., Jehin, E., Delrez, L., Pozuelos, F. J., Barkaoui, K., McCormick, C., Queloz, D., Triaud, A. H. M. J., & Broome, M. (2020). The continuing search for evidence of tidal orbital decay of hot Jupiters. The Astronomical Journal, 159(4), Article 150. https://doi.org/10.3847/1538-3881/ab7374
35. Penev, K., Bouma, L. G., Winn, J. N., & Hartman, J. D. (2018). Empirical tidal dissipation in exoplanet hosts from tidal spin-up. The Astronomical Journal, 155(4), Article 165. https://doi.org/10.3847/1538-3881/aaaf71
36. Perez-Becker, D., & Showman, A. P. (2013). Atmospheric heat redistribution on hot Jupiters. The Astrophysical Journal, 776(2), Article 134. https://doi.org/10.1088/0004-637X/776/2/134
37. Poddaný, S., Brát, L., & Pejcha, O. (2010). Exoplanet Transit Database: Reduction and processing of the photometric data of exoplanet transits. New Astronomy, 15(3), 297–301. https://doi.org/10.1016/j.newast.2009.09.001
38. Püsküllü, Ç., Soydugan, F., Erdem, A., & Budding, E. (2017). Photometric investigation of hot exoplanets: TrES-3b and Qatar-1b. New Astronomy, 55, 39–47. https://doi.org/10.1016/j.newast.2017.04.001
39. Ricker, G. R., Winn, J. N., Vanderspek, R., Latham, D. W., Bakos, G. Á., Bean, J. L., Berta-Thompson, Z. K., Brown, T. M., Doty, J. P., Dunger, R., Fűrész, G., McCullough, P. R., Morton, T. D., Paegert, M., Palle, E., Pepe, F., Queloz, D., Sasselov, D., Seager, S., ... Villasenor, J. (2015). Transiting Exoplanet Survey Satellite. Journal of Astronomical Telescopes, Instruments, and Systems, 1(1), Article 014003. https://doi.org/10.1117/1.JATIS.1.1.014003
40. Rogers, T. M., & Komacek, T. D. (2014). Magnetic effects in hot Jupiter atmospheres. The Astrophysical Journal, 794(2), Article 132. https://doi.org/10.1088/0004-637X/794/2/132
41. Scargle, J. D. (1982). Studies in astronomical time series analysis: II. Statistical aspects of spectral analysis of unevenly spaced data. The Astrophysical Journal, 263, 835–853. https://doi.org/10.1086/160554
42. Schwarz, G. (1978). Estimating the dimension of a model. The Annals of Statistics, 6(2), 461–464. https://doi.org/10.1214/aos/1176344136
43. Sokov, E. N., Sokova, I. A., Dyachenko, V. V., Rastegaev, D. A., Burdanov, A., Rusov, S. A., Benni, P., Shadick, S., Errmann, R., Adam, C., Puchalski, D., Tlatov, A., Berthold, T., Gennaro, M., & Velichko, S. F. (2018). Transit timing analysis of the exoplanet TrES-5 b. Possible existence of the exoplanet TrES-5 c. Monthly Notices of the Royal Astronomical Society, 480(1), 291–301. https://doi.org/10.1093/mnras/sty1615
44. Southworth, J., Dominik, M., Jørgensen, U. G., Andersen, M. I., Bozza, V., Burgdorf, M. J., D'Ago, G., Dib, S., Figuera Jaimes, R., Fujii, Y. I., Gillbart, S., Haugbølle, T., Hinse, T. C., Hundertmark, M., Khalouei, E., Korhonen, H., Longa-Peña, P., Mancini, L., Peixinho, N., ... Von Essen, C. (2019). Transit timing variations in the WASP-4 planetary system. Monthly Notices of the Royal Astronomical Society, 490(3), 4230–4236. https://doi.org/10.1093/mnras/stz2602
45. Su, L. H., Jiang, I. G., Sariya, D. P., Lee, C. Y., Yeh, L. C., Mannaday, V. K., Thakur, P., & Griv, E. (2021). Are there transit timing variations for the exoplanet Qatar-1b? The Astronomical Journal, 161(3), Article 108. https://doi.org/10.3847/1538-3881/abd4d8
46. VarAstro. (2026, 26 Şubat). Variable Star and Exoplanet Section of Czech Astronomical Society. https://var.astro.cz/en/
47. Von Essen, C., Schröter, S., Agol, E., & Schmitt, J. H. M. M. (2013). Qatar-1: Indications for possible transit timing variations. Astronomy & Astrophysics, 555, Article A92. https://doi.org/10.1051/0004-6361/201321407