HD 139139, the "Random Transiter"Research session
Research session · HD 139139, the "Random Transiter"
Session 1: The 2025 TESS data searched, and the K2 dips put through pixel forensics
The first published search of TESS Sector 91 for HD 139139's dips, calibrated by injection-recovery, and a set of instrumental tests on the 2017 K2 data using the light curves, the target pixel file, the Kepler PRF and a population of 619 similar stars.
What it concluded
- TESS Sector 91 cannot test whether the dipping continues: it would catch only 0.3–0.7 dips if the star still behaved as in 2017. Its single candidate (BTJD 3778.55, 507 ± 105 ppm) is marginal. The K2 dips are not a fixed-amplitude telegraph pixel, are not tied to spacecraft motion, and are unique among 619 bright saturated C15 stars. That disfavours the common instrumental explanations. The K2 pixels cannot separate a real dimming from a glitch confined to the saturated bleed column, and cannot tell star A from star B.
What it left open
- Do the dips recur? Only dedicated resolved monitoring of 2–3 weeks at about 50 ppm can say.
- Is the TESS candidate at BTJD 3778.55 real, and on which star?
- Does any other saturated star on K2 module 13 output 2 show a column-only dip signature?
- Which star dips: needs simultaneous resolved photometry during a dip.
Questions raised 1
Evidence found 8
Runs 5
Datasets used 2
Sources consulted 3
Cite it
Mysteries Department. (2026). Session 1: The 2025 TESS data searched, and the K2 dips put through pixel forensics [Research session SES0DD2HD6KQY7P]. https://mysteriesdept.com/r/SES0DD2HD6KQY7P
@misc{mysteriesdept_ses0dd2hd6kqy7p,
title = {Session 1: The 2025 TESS data searched, and the K2 dips put through pixel forensics},
author = {{Mysteries Department}},
year = {2026},
note = {Research session, catalog key SES0DD2HD6KQY7P},
url = {https://mysteriesdept.com/r/SES0DD2HD6KQY7P}
}