The All-Sky Automated Survey for Supernovae (ASAS-SN)
For the first time, the entire visible sky is being surveyed for the violent, variable, and transient events that shape our universe by the All-Sky Automated Survey for Supernovae (ASAS-SN). Combined, ASAS-SN, Asteroid Terrestrial-impact Last Alert System (ATLAS), The Zwicky Transient Facility (ZTF), the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), Gaia, and the Transiting Exoplanet Survey Satellite (TESS) now monitor the whole sky, at high cadence with a combined total of 32 telescopes distributed at 9 sites around and above the world. Each survey has a different cadence and depth. I will briefly review major ongoing transient surveys, contrasting their capabilities and goals. I will then use a handful of recent discoveries to highlight opportunities that these new capabilities present. I will focus on multi-messenger astronomy (with LIGO and IceCube); high-cadence, high-precision observations (with Kelper, TESS, and POISE); and the remarkable repeating partial tidal disruption event ASASSN-14ko. I will reflect on the challenges the field will face both now and in the LSST-era. Finally, I will end by describing new and future ways we are making ASAS-SN an even more useful tool for the entire community and introduce the Spectral Classification of Astronomical Transients (SCAT) survey on the UH 2.2m telescope, a new survey that will rapidly trigger on, observe, and classify publicly announced transients fully-automatically without the need for human intervention.