Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
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SEARCHING FOR TRANSIT TIMING VARIATIONS AND FITTING A NEW EPHEMERIS TO TRANSITS OF TRES-1 B

  • Received : 2020.10.18
  • Accepted : 2022.07.01
  • Published : 2022.08.31
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Abstract

Based on the light an exoplanet blocks from its host star as it passes in front of it during a transit, the mid-transit time can be determined. Periodic variations in mid-transit times can indicate another planet's gravitational influence. We investigate 83 transits of TrES-1 b as observed from 6-inch telescopes in the MicroObservatory robotic telescope network. The EXOTIC data reduction pipeline is used to process these transits, fit transit models to light curves, and calculate transit midpoints. This paper details the methodology for analyzing transit timing variations (TTVs) and using transit measurements to maintain ephemerides. The application of Lomb-Scargle period analysis for studying the plausibility of TTVs is explained. The analysis of the resultant TTVs from 46 transits from MicroObservatory and 47 transits from archival data in the Exoplanet Transit Database indicated the possible existence of other planets affecting the orbit of TrES-1 and improved the precision of the ephemeris by one order of magnitude. We now estimate the ephemeris to be (2 455 489.66026 BJDTDB ± 0.00044 d) + (3.0300689 ± 0.0000007) d × epoch. This analysis also demonstrates the role of small telescopes in making precise midtransit time measurements, which can be used to help maintain ephemerides and perform TTV analysis. The maintenance of ephemerides allows for an increased ability to optimize telescope time on large ground-based telescopes and space telescope missions.

Keywords

Acknowledgement

This publication makes use of the EXOTIC data reduction package from Exoplanet Watch, a citizen science project managed by NASA's Jet Propulsion Laboratory on behalf of NASA's Universe of Learning. This work is supported by NASA under award number NNX16AC65A to the Space Telescope Science Institute. This research has made use of the data provided by the MicroObservatory telescope network in addition to the astropy.io.fits and astropy.timeseries.LombScargle Python modules. This research has also incorporated historical data from the Exoplanet Transit Database. Special thanks to Yves Jongen, Vicenc Ferrando, Aleksandra Selezneva, Mario Morales, Rene Roy, Marc Bretton, Anael Wunsche, Mohammed Talafha, Francisco Jimenez Alvarado, Dominika Durovcikova, Karol Petrik, Ramon Naves, David Molina, Sean Balkwill, Alexander, Jennifer Eastman, Steffen Shaigec of the Athabasca University Geophysical Observatory, Mickie Wiebe, Terry Youngman, Kevin B. Alton, Ferran Grau Horta, Mark Salisbury, Alessandro Marchini, Juanjo Gonzalez, Katie Iadanza, Thomas Balonek, Fernand Emering, Bradley Walter et al. of the Paul and Jane Meyer Observatory (PJMO), Viktoriia Krushevska and Yuliana Kuznyetsova of the Main Astronomical Observatory of the NAS of Ukraine, Maksim V. Andreev of the ICAMER Observatory of the NAS of Ukraine, Darryl Sergison, Martin Vrastak, Lubos Brat, Manfred Raetz, Stan Shadick, Thomas Sauer, Radek Dreveny, Tomas Kalisch, Joe Garlitz, and Bruce Gary for providing these observations. Further, we would like to thank the AAVSO observers with observer codes GELD, HTAA, HAMA, HLAC, MTRC, NCAA, OXEA, RAKB, SHAF, SJOR, AKV, URMA, KMUA, KADB, LGEC, VJCA, SNIC, KELA, FMAA, DJJB, JBEB, GBRC, and LDJC for uploading transits of TrES-1 b to the AAVSO database. We would also like to thank Dr. Robert Zellem for helping us with using EXOTIC and analyzing TTVs.

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