TIC 399544063
An uncatalogued eclipsing-binary candidate from TESS.
Eclipsing-binary candidate: 0.6929-day period, a 5.25% primary eclipse, a 4.82% secondary eclipse at phase 0.597. Automated cross-checks question this period - see below.
This light curve is smooth and sinusoidal rather than eclipse-shaped - typical of a close pair distorted by each other's gravity, or of a signal that is not an eclipse - so the eclipse-geometry estimates do not apply. The drawing is generic; the glow still follows the real light curve.
Not to scale. 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 (6,322 K). Only the relative orbit is shown; both stars really circle their common centre of mass. Animated about 2,494x 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.
- Secondary2026-10-19 12:33 UTC
- Primary2026-10-19 19:16 UTC
- Secondary2026-10-20 05:11 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 0.491% (observed minus binned median).
Automated cross-checks question this period - see Caveats below.
- Period
- 0.69290 d
- Primary depth
- 5.25%
- Secondary depth
- 4.82%
- Epoch (T0)
- 2882.363 BTJD
- Duration
- 0.96 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 58.
- 30.3
- 0.11 px2"
- -0.3975 phase
- none
- 0.85
- 58
The dimming is centred on the target star. No nearby contaminant detected.
- Centroid offset
- 0.11 px
- Difference SNR
- 30.3
- Capable neighbour
- none
- TESS sector
- 58
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.
It is about 1,254 light years away: the light TESS recorded left it around 1,254 years ago.
Together the two stars give off about 3.7 times the Sun's light in Gaia's band - before correcting for interstellar dust, which only makes distant stars look fainter.
Its colour is close to the Sun's.
Source: ESA Gaia DR3, source 437999394754571008.
Gaia's position measurements fit this source poorly (RUWE 1.96, above the usual 1.4). That often means more than one star is there - most likely a wider third star or an unresolved neighbour, since a tight eclipsing pair barely moves Gaia's image. Context, not confirmation.
- Distance
- 385 +/- 5 pc
- Light-travel time
- ~1,254 years
- Apparent G
- 11.16
- Absolute G
- 3.24
- Colour BP-RP
- 0.84
- RUWE
- 1.96
- Match offset
- 0.13 arcsec
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 47.0 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
- 0.69290 d
- BLS period
- 0.69290 d
- Odd/even z
- 1.82
Caveats
Known limitations and things to check.
Cross-check:The light curve is dominated by a smooth sinusoid with period 0.13850 d (Lomb-Scargle power 0.88); the adopted 0.69290 d is 5.00 x that. The true period is more likely 0.13850 d (pulsation or spots) or 0.27700 d (contact binary), and the 'eclipses' may not be eclipses.
VIIIInstrument
Raw values, fits and technical details.
Instrument
Raw values, fits and technical details.
Full statistics
- 0.69290 d
- 0.69290 dsame
- 5.25% +/- 0.03%seen 66/66
- ML screening score
- 0.952logistic_regression
- 4.82% +/- 0.06%phase 0.597, 75 sigma
- 1.82< 3
- 0.1385 dpower 0.88 - FLAG
- 1.0 h
- Distance (TIC, Gaia-based)
- 272 pc
- 11.10 / 10.66
- 6322 K / 1.39 Rsun
- RA / Dec (J2000)
- 02h 40m 29.5s +47d 00m 17s
- 947.4 / 30.3
- 19,214 ptsover 754 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 = 1.82 (gate 3.0): alternate eclipses match, so the BLS period stands.
O - C timing
66 eclipses timed, rms 4.54 min, reduced chi-square 294.10 (64 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 = 0.692903 +/- 0.000000 d.