TIC 43785616
An uncatalogued eclipsing-binary candidate from TESS.
Eclipsing-binary candidate: 17.9113-day period (twice the BLS period), a 1.99% primary eclipse, no significant secondary eclipse.
TIC 43785616 is a candidate eclipsing binary star with an orbital period of 17.91 days, identified through automated analysis of TESS photometry. The system shows a primary eclipse with a dimming of 1.15%, detected with a signal-to-noise ratio of 160.8 in the BLS periodogram. Pixel-level image analysis confirms the signal at the target location with a peak signal-to-noise of 27.7, though the centroid offset of 6.7 arcseconds warrants continued attention. No secondary eclipse was detected. The target does not appear in six major variable-star catalogs, making it a novel candidate. However, alternating eclipses show significantly different depths, suggesting the true orbital period is double the initial measurement. This photometric signature, while not affecting the timing analysis, indicates caution is warranted in interpreting this candidate's properties.
- Surface brightness ratio
- companion faint - no secondary eclipse
- Companion temperature
- below ~3,095 K
- Companion / star radius
- ~0.14
- Face hidden at primary eclipse
- ~2%
- Separation
- ~19 x the star's radius
- Eccentricity
- consistent with circular
Zoomed: both stars drawn about 4x 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 (5,925 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 64,481x 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.
- Secondary2026-10-20 00:29 UTC
- Primary2026-10-28 23:25 UTC
- Secondary2026-11-06 22:21 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 0.193% (observed minus binned median).
Alternate eclipses differ in depth, so the true period is twice the search period.
- Period
- 17.91130 d
- Primary depth
- 1.99%
- Epoch (T0)
- 2175.208 BTJD
- Duration
- 8.40 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 32.
- 27.7
- 0.32 px7"
- 0.0000 phase
- TIC 437856044.54 px, dT 1.0
- 0.84
- 32
The dimming is centred on the target star. No nearby contaminant detected.
- Centroid offset
- 0.32 px
- Difference SNR
- 27.7
- Capable neighbour
- TIC 43785604
- TESS sector
- 32
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 1,907 light years away: the light TESS recorded left it around 1,907 years ago.
Together the two stars give off about 5.6 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 3182410104496905344.
Gaia's position measurements fit this source poorly (RUWE 4.34, 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
- 585 +/- 24 pc
- Light-travel time
- ~1,907 years
- Apparent G
- 11.63
- Absolute G
- 2.79
- Colour BP-RP
- 0.86
- RUWE
- 4.34
- Match offset
- 0.24 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 -10.3 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
- 17.91130 d
- BLS period
- 8.95565 d
- Odd/even z
- 137.15
Caveats
Known limitations and things to check.
- Period alias:Odd/even eclipse-depth z-score is 137.15 (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, 17.911302 d, in any write-up.
VIIIInstrument
Raw values, fits and technical details.
Instrument
Raw values, fits and technical details.
Full statistics
- 17.91130 d
- 8.95565 dalias
- 1.99% +/- 0.01%seen 2/2
- ML screening score
- 0.370logistic_regression
- < 0.11%none at 5 sigma
- 137.15> 3: alias
- 3.5932 dpower 0.04
- 8.4 h
- Distance (TIC, Gaia-based)
- 264 pc
- 11.62 / 11.16
- 5925 K / 1.19 Rsun
- RA / Dec (J2000)
- 05h 09m 58.9s -10d 16m 51s
- 160.8 / 27.7
- 17,562 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 = 137.15 (gate 3.0): alternate eclipses differ, so the true period is 2 x 8.9557 = 17.9113 d.