5 Years of Defocused Observations of Exoplanet Transits with T100: Timing Perspective

TL;DR

This paper reviews five years of exoplanet transit observations using the defocusing technique with the T100 telescope, emphasizing improved timing precision through high photometric accuracy.

Contribution

It demonstrates the effectiveness of the defocusing technique in achieving high-precision transit timing over an extended observational period.

Findings

Enhanced timing precision achieved with defocusing method.

Reduced noise from atmospheric scintillation and tracking errors.

Long-term transit timing data collected over five years.

Abstract

We have been carrying out a program for over five years to observe transits of selected exoplanets with 1-meter Turkish Telescope, T100 (Ba\c{s}t\"urk et al. 2014, 2015), by making use of the well-established defocusing technique (Southworth et al. 2009) to achieve high photometric precision. In this contribution, we review the results of our observing program in timing perspective. The basic idea behind defocusing technique is to have the advantage of posing the detector for longer duration in the observations of bright stars, otherwise observed within very short integration times. Then the effect of the photon noise is diminished, which dominates in the short cadence observations. Longer exposures also help in reducing the noise contribution of the atmospheric scintillation. Noise contributions of the imperfect tracking and flat-fielding are mitigated by integrating over a larger area on the detector as well. Although fewer images can be acquired in a given time, we argue that the timing precision is improved because of better photometric precision. This contribution has been supported by T\"UB\.ITAK-3001 project 116F350.