COUNTESS. I. A Uniformly Vetted Catalog of Known and New Transiting Exoplanets in the TESS Northern Continuous Viewing Zone
October 2026 • 2026ApJS..286...42H
Abstract • The Transiting Exoplanet Survey Satellite (TESS) has transformed the study of nearby exoplanetary systems; however, its nominal observing strategy limits sensitivity to planets with orbital periods shorter than ~10 days for most parts of the sky. The two TESS Continuous Viewing Zones (CVZs) provide extended temporal baselines that help overcome this limitation, enabling the detection of longer-period (>10 days) transiting planets around nearby stars. Here, we present COUNTESS, a transit-search pipeline optimized for long-baseline TESS observations that combines multisector light curves with heterogeneous cadences, and implements fast-folding box least-squares period detection, vetting, and statistical validation. As a first application of the pipeline, we conducted a search on the primary and first extended mission photometry in the TESS northern CVZ. For this analysis, we used Gaia Data Release 3 and Two Micron All Sky Survey photometry to homogeneously derive a stellar catalog of FGKM stars for the TESS northern CVZ, resulting in a sample of 391,059 stars. We used COUNTESS to search for transiting planets around 26,114 of these stars with TESS-SPOC light curves and assessed its performance, recovering 115 out of 159 known TESS Objects of Interest (TOIs; 0.85 < P < 124.72 days; 1.03 < Rp < 16.35 R⊕). Additionally, we identified 10 new exoplanet candidates (1.20 < P < 34.62 days; 1.73 < Rp < 4.19 R⊕) that passed vetting tests, including two new statistically validated sub-Neptunes, TIC 219893931 b and TIC 237254473 b. COUNTESS enables extended-baseline TESS analyses and identification of longer-period planets, establishing a foundation for future exoplanet demographic studies, including comparisons with the Kepler Space Telescope and K2.
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