R-band Transit Photometry of TESS Object of Interest TOI 5868: Ground-Based Follow-Up and FWHM-Vetted Detection

As part of the 2025 NASA SCHAR School internship program, we obtained ground-based R‑band time series photometry of the TESS Object of Interest TOI 5868.01 By using a calibrated and quality-checked image sequence, we carried out differential aperture photometry and modeled the resulting light curve to measure the mid-transit time and depths. By applying FWHM vetting threshold = 6.5 px, only 62 of the 280 or 22.14% were retained as “good” data. Our best-fit model yields a mid-transit tim of BJD − 2459000 = 132.000125 ppt and a planet-to-star radius ratio of R_p/R_s = 0.0985. This corresponds to a transit depth of d = (R_p/R_s)^2 = 0.0097000 or .97%. The out-of-transit RMS of the detrended light curve is 11.42 ppt. We show the observing setup, calibration procedure, quality control, and consistency checks. This study provides significant evidence for the planetary nature of TOI 5868.01, by recovering a transit depth and mid-transit timing that corroborates TESS predictions. Our results highlight the valuable role that well-calibrated follow up can play in broader exoplanet validations. Such efforts, not only help confirm candidates from space based surveys such as TESS, but also contribute to maintaining accurate orbital ephemerides and ruling out false positives.This work ultimately shows that precise data reduction and quality can enable modest student led projects to make meaningful contributions to the discovery and study of new exoplanetary systems.