Breakthrough Listen Follow-up of the Random Transiter (EPIC 249706694/HD 139139) with the Green Bank Telescope

TL;DR

This study conducted follow-up radio observations of the star EPIC 249706694, which exhibited unusual transit events, but found no signs of technosignatures, setting an upper limit on potential extraterrestrial signals.

Contribution

First follow-up radio search for technosignatures from EPIC 249706694 with Green Bank Telescope, constraining possible alien transmissions.

Findings

No technosignatures detected above threshold

Set upper limit of 10 TW for potential alien signals

Confirmed absence of detectable signals during observation period

Abstract

The star EPIC 249706694 (HD 139139) was found to exhibit 28 transit-like events over an 87 day period during the Kepler mission's K2 Campaign 15 (Rappaport et al. 2019). These events did not fall into an identifiable pattern and could not be explained by a multitude of transit scenarios explored by the authors. We conduct follow-up observations at C-band frequencies with the Green Bank Telescope as part of the ongoing Breakthrough Listen search for technosignatures. We search for narrow band signals above a signal-to-noise threshold of 10 and with Doppler drift rates within +-5 Hz/s. We detect no evidence of technosignatures from EPIC 249706694 and derive an upper limit for the EIRP (Equivalent Isotropic Radiated Power) of putative transmissions to be 10 TW.