TIC 318620649
An uncatalogued eclipsing-binary candidate from TESS.
Eclipsing-binary candidate: 27.6687-day period (twice the BLS period), a 1.22% primary eclipse, a 1.01% secondary eclipse at phase 0.500.
TIC 318620649 is a candidate eclipsing binary star detected through automated analysis of TESS photometry. The system shows a primary eclipse with a depth of 0.92% and an orbital period of 27.67 days, along with a secondary eclipse detected at 7.0 sigma significance. The detection achieved a strong signal-to-noise ratio of 60.8 in the Box Least Squares search, and pixel-level image analysis confirmed the source location near the target with a peak signal-to-noise of 7.3. The target does not appear in any of six major variable-star catalogs. However, data quality checks reveal that alternating eclipses differ significantly in depth, suggesting the initially measured period may have been underestimated - the corrected orbital period of 27.67 days accounts for this pattern.
- Surface brightness ratio
- 0.82
- Companion temperature
- ~6,293 K
- Companion / star radius
- ~0.11
- Face hidden at primary eclipse
- ~1%
- Separation
- ~40 x the star's radius
- Eccentricity
- consistent with circular
- Secondary eclipse phase
- 0.500 measured, 0.500 in this orbit
Zoomed: both stars drawn about 8x 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 (6,719 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 99,607x 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.
- Primary2026-10-26 01:28 UTC
- Secondary2026-11-08 21:18 UTC
- Primary2026-11-22 17:31 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 0.483% (observed minus binned median).
Alternate eclipses differ in depth, so the true period is twice the search period.
- Period
- 27.66869 d
- Primary depth
- 1.22%
- Secondary depth
- 1.01%
- Epoch (T0)
- 1960.054 BTJD
- Duration
- 5.86 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 84.
- 7.3
- 0.22 px5"
- 0.0000 phase
- TIC 3186206621.45 px, dT 3.8
- 0.62
- 84
The dimming is centred on the target star. No nearby contaminant detected.
- Centroid offset
- 0.22 px
- Difference SNR
- 7.3
- Capable neighbour
- TIC 318620662
- TESS sector
- 84
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?
The latest ground-survey file does not include this candidate yet, so there is no independent ZTF check to show.
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
- 27.66869 d
- BLS period
- 13.83435 d
- Odd/even z
- 4.33
Caveats
Known limitations and things to check.
- Period alias:Odd/even eclipse-depth z-score is 4.33 (gate > 3.0): alternating eclipses differ significantly in depth, the signature of a true period double what BLS found. Pixel-check confirmation and eclipse timing are unaffected - report the corrected period, 27.668693 d, in any write-up.
VIIIInstrument
Raw values, fits and technical details.
Instrument
Raw values, fits and technical details.
Full statistics
- 27.66869 d
- 13.83435 dalias
- 1.22% +/- 0.25%seen 4/5
- ML screening score
- 0.556logistic_regression
- 1.01% +/- 0.04%phase 0.500, 28 sigma
- 4.33> 3: alias
- 0.5123 dpower 0.01
- 5.9 h
- Distance (TIC, Gaia-based)
- 1790 pc+/- 69
- 13.01 / 12.24
- 6719 K / 6.98 Rsun
- RA / Dec (J2000)
- 23h 18m 23.7s +58d 23m 56s
- 60.8 / 7.3
- 41,256 ptsover 1680 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 = 4.33 (gate 3.0): alternate eclipses differ, so the true period is 2 x 13.8343 = 27.6687 d.
O - C timing
4 eclipses timed, rms 16.70 min, reduced chi-square 76.06 (2 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 = 27.668229 +/- 0.000048 d.