Oral Abstract

Oral Contribution (O0.7) David Modiano (Anton Pannekoek Institute)

The Transient UV Objects Project

With the recent advances in time-domain astronomy, transient searches have become prevalent through a range of facilities at all electromagnetic wavelengths. However, the ultraviolet (UV) is a notable exception, in that despite being used often for follow-up studies of transients, it has been significantly under-utilised for serendipitous transient discoveries. This presents a considerable obstacle to a complete multi-wavelength understanding of transient phenomena in the Universe, and could also mean that we are foregoing potential discoveries of completely unknown types of transients. To explore this gap, we have developed the Transient UV Objects (TUVO) project. We make use of a pipeline we constructed which processes all data from Swift’s UV telescope UVOT in order to search for serendipitous UV transients using difference image analysis, in near real-time. From 2020-09-15 we have to date processed 24,788 individual UVOT images and detected 3243 candidate transients, an average rate of ~20 candidates per day. The types of sources we find include variable stars, flares, dwarf novae, novae, outbursts from X-ray binaries, tidal disruption events, variable active galactic nuclei, and supernovae. Of the daily candidates, a few typically represent previously unreported new transients, or undiscovered outbursts of previously known sources. This subset of discoveries are our prime targets for further study, for which we have undertaken spectroscopic follow-up campaigns with optical ground-based observatories (INT, SALT) in order to classify and characterise the interesting transients. In this talk I will give an overview of the TUVO project, the functioning of the pipeline, and initial results.