A Survey of Comets using TESS

We are performing a survey of comets that serendipitously passed through the TESS (Transiting Exoplanet Survey Satellite) field of view. Using the full-frame images, we are monitoring the comets' short- and long-term temporal behavior, tracking secular changes in activity, measuring the nucleus spin state, mapping and analyzing variability in the coma morphology, and searching for spontaneous outbursts. TESS' instrumental stability, sampling cadence (every 10 or 30 minutes) and long-duration observation baseline (each sector spans 27 days) produce a dataset of unprecedented quality for this study, which has the potential to constrain the characteristics of more than 100 comets in various families. The data are especially promising for identifying rotation periods longer than 24 hours, which are under-sampled in ground-based observations, and for capturing the onset and early stages of outbursts, which have previously only been recorded on three occasions. By aligning and co-adding numerous images, we can also investigate weak activity in faint and distant comets, and search for dust trails that will constrain the comets' dust properties and total mass loss rates.

We will present results from our analyses of these data. Preliminary results include: The discovery that the Oort cloud comet, C/2014 UN271 (Bernardinelli-Bernstein), which may have the largest nucleus ever discovered, was exhibiting activity as early as 2018 when it was at a heliocentric distance of 23 AU; Observations of the residual dust cloud of comet C/2020 F8 (SWAN), which broke up in the spring of 2020, extending over a distance of 10 million kilometers; High cadence observations of the onset of at least two outburst events (46P/Wirtanen and 398P/Boattini) that both exhibit a two-phase brightening; and the discovery of four previously unknown dust trails (46P/Wirtanen, 48P/Johnson, 66P/du Toit, and 371P/LINEAR-Skiff).