Countess I: A uniformly scanned catalog of known and new transiting exoplanets in TESS’s northern continuous viewing region.

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Countess I: A uniformly scanned catalog of known and new transiting exoplanets in TESS's northern continuous viewing region. — Planet radius distribution and orbital period of TOIs, new false positives and planet candidates. Countess discovered 38 new planetary signals, 28 of which are FPs, through Triceratops validation and LEOVetter pixel scanning. Note that square symbols indicate TOI FPs that were successfully retrieved as FPs by COUNTESS. — Astronomical ph.EP

The Transiting Exoplanet Survey Satellite (TESS) has transformed the study of nearby exoplanetary systems; However, its nominal observing strategy limits its sensitivity to planets with orbital periods of less than ∼10 days for most parts of the sky.

The two TESS Continuous Viewing Zones (CVZs) provide extended time baselines that help overcome this limitation, enabling the detection of longer-period (>10 days) transiting planets around nearby stars.

Here we present COUNTESS, a transient search pipeline optimized for long-baseline TESS observations that combines multi-segment light curves and heterogeneous rhythms, and performs rapid BLS period detection, auditing, and statistical verification. As a first application of the pipeline, we conducted photometry research for the initial and first extended mission at TESS north of the CVZ.

In this analysis, we used Gaia DR3 photometry and 2MASS to derive a homogeneous stellar catalog of FGKM stars for the TESS north CVZ, resulting in a sample of 391,059 stars. We used COUNTESS to search for transiting planets around 26,114 of these TESS-SPOC stars and evaluated its performance, recovering 115 out of 159 known TESS objects of interest (TOIs; 0.85 days).

⊕⊕).

In addition, we identified 10 new exoplanet candidates (1.20 days

⊕⊕) that have passed screening tests, including two new statistically validated subplanets, TIC 219893931b and TIC 237254473b. COUNTESS enables expanded TESS core analyzes and identification of longer-period planets, laying the foundation for future exoplanetary demographic studies, including comparisons with Kepler and K2.

Andrew Hutnesky, Rachel B. Fernandez, Kevin K. Hardegree-Ullman, Stephen Giacalone, Kirsten M. Pauley, Christo Mint, Michelle Kunimoto, Galen J. Bergsten, Saki Burri, Jesse L. Christiansen, Brandon Radzoom, Suvrath Mahadevan

Comments: 26 pages, 10 figures, 6 tables; It was resubmitted to AAS journals after addressing reviewer comments
Topics: Earth and planetary astrophysics (astro-ph.EP); Astrophysical Instruments and Methods (astro-ph.IM); Solar and stellar astrophysics (astro-ph.SR)
Cite as: arXiv:2606.13789 [astro-ph.EP] (Or arXiv:2606.13789v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2606.13789
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Submission date
Written by: Andrew Hutneski
[v1] Thursday 11 June 2026 at 18:01:13 UTC (14,312 KB)
https://arxiv.org/abs/2606.13789
astrobiology, astronomy, exoplanets,