False positives

15 chapters, each an animated explainer with its physics and sources. Every drawing says whether it is an illustration, a model from stored values, or real data, and by how much it is exaggerated. Only the transit chapter is something SetuHQ itself does.

Chapter 10 of 15

False positives

Many transit-like dips are not planets on the target star. A dip is evidence; vetting asks what else could make it. This is where SetuHQ's own checks live.

Illustration
Five ways to fake a planet, each with its sky geometry on a grid of TESS pixels (21 arcseconds each, drawn to scale) and the light curve it makes: an eclipsing binary with a V-shaped grazing eclipse; a background eclipsing binary diluted by the target's light; a hierarchical triple; odd and even eclipses of different depth when the period is half the true one; and an instrumental jump such as a momentum dump.

How often, and what SetuHQ checks

QuantityValueFrom
Kepler candidates that were false positives9.4%overall; 17.7% for giants (Fressin et al. 2013)
TESS prime-mission TOIs found false by follow-up565 of 2,241 (≈25%)Guerrero et al. 2021
A 50% binary eclipse diluted 1,000 times500 ppmδ_obs = δ_true · F_target/F_total [calc]: the depth of a small planet
pi Men c's shape, T23/T140.95flat-bottomed (U), not V [calc from the transit chapter]

SetuHQ's vetting flags, from the light curve alone: odd_even_mismatch (odd and even depths differ), secondary_eclipse (a dip at phase 0.5), low_snr, too_short, edge_event and insufficient_points. It has no pixel-level centroid or difference-image check and no statistical validation, so a blended background binary can pass. See the reviewers › · See a vetted case ›

Sources

↑ ↓ to move · Enter to open · Esc to close