TIC 250549396
An uncatalogued eclipsing-binary candidate from TESS.
Eclipsing-binary candidate: 2.1929-day period, a 8.52% primary eclipse, no significant secondary eclipse.
- Surface brightness ratio
- companion faint - no secondary eclipse
- Companion temperature
- below ~2,997 K
- Companion / star radius
- ~0.29
- Face hidden at primary eclipse
- ~9%
- Separation
- ~5.4 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 follow temperature on a stellar colour scale, saturated so the differences show; the star's is its catalogue value (5,661 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 7,894x 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 14:41 UTC
- Secondary2026-10-20 17:00 UTC
- Primary2026-10-21 19:19 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 1.834% (observed minus binned median).
Clear, repeating eclipses with a consistent period and depth.
- Period
- 2.19290 d
- Primary depth
- 8.52%
- Epoch (T0)
- 1469.190 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 6.
- 41.1
- 0.03 px1"
- 0.0025 phase
- TIC 2505493951.73 px, dT 2.3
- 0.85
- 6
The dimming is centred on the target star. No nearby contaminant detected.
- Centroid offset
- 0.03 px
- Difference SNR
- 41.1
- Capable neighbour
- TIC 250549395
- TESS sector
- 6
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 1,861 light years away: the light TESS recorded left it around 1,861 years ago.
Together the two stars give off about 3.2 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 3117680270125779840.
Gaia's measurements fit a single point of light well (RUWE 1.20), as expected for a pair too close for Gaia to separate.
- Distance
- 571 +/- 6 pc
- Light-travel time
- ~1,861 years
- Apparent G
- 12.19
- Absolute G
- 3.41
- Colour BP-RP
- 0.96
- RUWE
- 1.20
- Match offset
- 0.18 arcsec
The ground-survey check
An independent instrument, different years: does real ZTF photometry show the eclipse at the period TESS measured?
- ZTF g (351 pts, 8 outliers)Not significant (p=0.01)
Folded at the TESS-measured period of 2.19290 d, no band shows a phase cluster tight enough to rule out chance. Ground-survey cadence is sparse - a handful of epochs per orbit - so this is the expected outcome for most real eclipses, not evidence against this one.
Source: ZTF public light-curve archive (IRSA), independent of the TESS data used to detect this candidate.
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
- 2.19290 d
- BLS period
- 2.19290 d
- Odd/even z
- 2.51
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
- 2.19290 d
- 2.19290 dsame
- 8.52% +/- 0.18%seen 9/9
- ML screening score
- 0.683logistic_regression
- < 0.46%none at 5 sigma
- 2.51< 3
- 2.1970 dpower 0.12
- 4.1 h
- Distance (TIC, Gaia-based)
- 563 pc+/- 12
- 12.20 / 11.70
- 5661 K / 2.04 Rsun
- RA / Dec (J2000)
- 06h 18m 17.9s -02d 52m 31s
- 837.8 / 41.1
- 904 ptsover 22 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 = 2.51 (gate 3.0): alternate eclipses match, so the BLS period stands.
O - C timing
9 eclipses timed, rms 4.40 min, reduced chi-square 3.92 (7 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 = 2.193713 +/- 0.000165 d.