TIC 77210120
An uncatalogued eclipsing-binary candidate from TESS.
Eclipsing-binary candidate: 1.5344-day period, a 4.58% primary eclipse, a 0.56% secondary eclipse at phase 0.295.
- Surface brightness ratio
- 0.12
- Companion temperature
- ~3,345 K
- Companion / star radius
- ~0.21
- Face hidden at primary eclipse
- ~5%
- Separation
- ~3.6 x the star's radius
- Eccentricity
- at least 0.321
- Secondary eclipse phase
- 0.295 measured, 0.299 in this orbit
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 follow temperature on a stellar colour scale, saturated so the differences show; the star's is its catalogue value (5,373 K). 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 5,524x 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.
- Primary2026-10-20 06:37 UTC
- Secondary2026-10-20 17:30 UTC
- Primary2026-10-21 19:27 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 42.741% (observed minus binned median).
Clear, repeating eclipses with a consistent period and depth.
- Period
- 1.53443 d
- Primary depth
- 4.58%
- Secondary depth
- 0.56%
- Epoch (T0)
- 3480.632 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 80.
- 134.5
- 0.12 px3"
- 0.0000 phase
- TIC 772101140.89 px, dT 2.4
- 0.80
- 80
The dimming is centred on the target star. No nearby contaminant detected.
- Centroid offset
- 0.12 px
- Difference SNR
- 134.5
- Capable neighbour
- TIC 77210114
- TESS sector
- 80
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?
- ZTF g (36 pts, 5 outliers)Confirmed (p=0.0060)
- ZTF r (39 pts, 3 outliers)Not significant (p=0.06)
Folded at the TESS-measured period of 1.53443 d, at least one band shows individual ZTF epochs - real observations, years apart - landing far below the baseline brightness and clustered in phase far tighter than chance would produce given how many such epochs that band has (p < 0.01, chance-corrected for the outlier count).
Source: ZTF public light-curve archive (IRSA), independent of the TESS data used to detect this candidate.
Real ZTF ground-survey photometry backs this period: one band shows epochs, years apart, landing more than 5 sigma below the baseline brightness and clustered in phase far tighter than chance would produce given how many such epochs that band has (p < 0.01) - a different instrument finding the same eclipse.
- Bands confirmed
- ZTF g
- Deepest clustered dip
- 7.2 sigma (ZTF g)
- Chance p-value
- 0.0060 (ZTF g)
- Period tested
- 1.53443 d
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
- 1.53443 d
- BLS period
- 1.53443 d
- Odd/even z
- 2.45
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
- 1.53443 d
- 1.53443 dsame
- 4.58% +/- 0.34%seen 16/16
- ML screening score
- 0.398logistic_regression
- 0.56% +/- 0.03%phase 0.295, 16 sigma
- 2.45< 3
- 10.5804 dpower 0.00
- 4.1 h
- Distance (TIC, Gaia-based)
- 1064 pc+/- 243
- 12.75 / 12.17
- 5373 K / 3.55 Rsun
- RA / Dec (J2000)
- 18h 02m 39.3s +09d 52m 27s
- 250.3 / 134.5
- 10,865 ptsover 26 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 = 2.45 (gate 3.0): alternate eclipses match, so the BLS period stands.
O - C timing
16 eclipses timed, rms 64.50 min, reduced chi-square 3764.97 (14 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 = 1.541195 +/- 0.000031 d.