NASA’s Transiting Exoplanet Survey Satellite, TESS, has identified more than 2,000 potential exoplanets in our local region of the Milky Way. Launched in 2018, TESS has already surveyed almost the entire sky once, and it’s now on its second pass. But along the way, TESS has also serendipitously found several objects that aren’t planets, highlighting its value as a multidisciplinary mission. (A list at the end of this article outlines some of the best non-planetary TESS finds.)
Among those unexpected finds is a recent gamma-ray burst (GRB), which TESS spotted in October 2020. GRBs are short-lived but powerful explosions that astronomers believe occur either when a massive star explosively dies or when two neutron stars merge. In both cases, the result is a black hole. These events release as much energy in a few seconds or minutes as the Sun puts out over its entire lifetime.
Another NASA telescope, Swift-BAT, discovered this GRB first. But Swift-BAT was unable to follow up on the blast immediately after its detection because it occurred too close to the Moon. Fortunately, TESS happened to be staring at just the right part of the sky — unhindered by the Moon from its viewpoint — and caught the event by sheer luck. TESS recorded the burst, which grew as bright as magnitude 15.1 for several minutes before it faded away. But that brief window of observation was crucial, providing astronomers with the data needed to calculate the GRB’s distance — nearly 12 billion light-years — among other things.
"Our findings prove this TESS telescope is useful not just for finding new planets, but also for high-energy astrophysics," said Krista Lynne Smith of Southern Methodist University in Dallas, Texas, in a press release. Smith led the work on the GRB, which was published April 14 in The Astrophysical Journal.