TIC 401936263
An uncatalogued eclipsing-binary candidate from TESS.
Eclipsing-binary candidate: 2.2010-day period, a 6.88% primary eclipse, no significant secondary eclipse.
TIC 401936263 is a candidate eclipsing binary star with an orbital period of 2.2010 days. TESS photometry detected a primary eclipse causing a 5.79% dimming of the star's light, with a strong signal-to-noise ratio of 271.2 in the automated search. Pixel-level image analysis confirmed the signal at the target's location with a peak signal-to-noise of 82.3, though the centroid offset measured 1.3 arcsec from the target itself. No secondary eclipse was detected in the data. The candidate does not appear in six major variable-star catalogs, making it a novel find. The automated pipeline's machine-learning classifier assigned it a score of 0.52, and the light curve passed all data quality checks without flags or issues.
- Surface brightness ratio
- companion faint - no secondary eclipse
- Companion / star radius
- ~0.26
- Face hidden at primary eclipse
- ~7%
- Separation
- ~5.3 x the star's radius
- Eccentricity
- consistent with circular
Zoomed: both stars drawn about 1x larger than their real size relative to the orbit, so they overlap for longer than the real eclipse lasts. A star's surface never gets dimmer during an eclipse - part of it is simply hidden. What drops is the total light we receive, shown exactly by the readout and bar below from the real light curve; the glow dims with it, exaggerated so small dips show. Colours are illustrative. The companion's colour, sizes and orbit shape are estimates from the eclipse depths, duration and timing, assuming central eclipses and spherical stars - good to perhaps tens of percent. Only the relative orbit is shown; both stars really circle their common centre of mass. Animated about 7,924x faster than real on average, slowing down through each eclipse, and starting from where the system is in its orbit right now. Hover to pause.
- Primary2026-10-19 09:01 UTC
- Secondary2026-10-20 11:26 UTC
- Primary2026-10-21 13:50 UTC
Computed from the fitted ephemeris. Approximate - not corrected for your location or for light-travel time across Earth's orbit.
The signal
A repeating, consistent dip in brightness.
Residual scatter 1.177% (observed minus binned median).
Clear, repeating eclipses with a consistent period and depth.
- Period
- 2.20102 d
- Primary depth
- 6.88%
- Epoch (T0)
- 1517.771 BTJD
- Duration
- 4.08 h
The catalog check
Cross-matched against known variable-star catalogs to rule out anything already listed.
- VSXNot found
- ASAS-SNNot found
- Gaia eclipsing-binary tableNot found
- Gaia variable classificationNot found
- TESS EB catalog (Prsa+2022)Not found
- ExoFOP TOI listNot found
0/6 catalogs list a known variable at this position.
No known variable star or catalogued match at this position.
- Catalogs checked
- 6
- Matches
- 0
The pixel check
Confirms the dimming is on the target star, not a nearby source.
Out/in share one sqrt colour scale; in-eclipse = out-of-eclipse minus difference. TESS sector 9.
- 82.3
- 0.06 px1"
- 0.0025 phase
- TIC 4019363052.14 px, dT 1.6
- 0.96
- 9
The dimming is centred on the target star. No nearby contaminant detected.
- Centroid offset
- 0.06 px
- Difference SNR
- 82.3
- Capable neighbour
- TIC 401936305
- TESS sector
- 9
The Gaia view
A second spacecraft's measurements: how far away the star is, how bright and what colour, and whether its position fits a single star.
The latest Gaia context file does not include this candidate yet, so there is no Gaia view to show.
The ground-survey check
An independent instrument, different years: does real ZTF photometry show the eclipse at the period TESS measured?
No ZTF observations at this position (declination -51.5 deg) - likely too far south for ZTF's footprint, which covers the sky north of roughly -31 deg. Not a mark against the candidate, just a gap in ground-survey coverage.
Fold it yourself
Adjust the period and watch the eclipse appear.
Shown at the true period. The raw light curve needed to re-fold at other periods has not been exported yet - this slider unlocks automatically once it is.
The period the pipeline measured. Drag the slider away from it and the eclipse smears out.
- True period
- 2.20102 d
- BLS period
- 2.20102 d
- Odd/even z
- 1.74
Caveats
Known limitations and things to check.
No caveats flagged: this candidate cleared every gate with no named exception. Follow-up observations would still be needed to confirm the stellar parameters.
VIIIInstrument
Raw values, fits and technical details.
Instrument
Raw values, fits and technical details.
Full statistics
- 2.20102 d
- 2.20102 dsame
- 6.88% +/- 0.23%seen 22/22
- ML screening score
- 0.518logistic_regression
- < 0.38%none at 5 sigma
- 1.74< 3
- 2.1992 dpower 0.15
- 4.1 h
- Distance (TIC, Gaia-based)
- 1798 pc+/- 62
- 13.91 / 13.38
- - / -
- RA / Dec (J2000)
- 09h 04m 41.3s -51d 32m 25s
- 271.2 / 82.3
- 1,966 ptsover 51 d
Eclipse close-ups
Same flux scale on both panels. Line: binned median. Shown in place of an orbit animation - this pipeline measures eclipses, it does not fit an orbit.
Period alias analysis
Odd/even depth z = 1.74 (gate 3.0): alternate eclipses match, so the BLS period stands.
O - C timing
21 eclipses timed, rms 7.22 min, reduced chi-square 12.59 (19 dof): more scatter than the timing errors explain - worth a closer look.
Each eclipse timed by fitting the star's own mean eclipse profile; fitted P = 2.200529 +/- 0.000046 d.