Finding Multi-Messenger Transients with Swift: Lessons learned from searching for MAXI, IceCube and LIGO/Virgo transients

We present results and lessons learned from multi-messenger and multi-telescope searches for X-ray and UV counterparts of transients, utilizing the Neil Gehrels Swift Observatory. Swift is unique in many ways, firstly it is a multi-wavelength observatory, observing in 0.5-150 keV in X-rays, and visible to UV in optical, utilizing the it's three instruments, the Burst Alert Telescope (BAT), X-ray telescope (XRT) and UV/Optical Telescope (UVOT). Secondly, Swift is a robotic telescope, capable of responding rapidly ( minutes to hours) to transient triggers from a variety of sources. Thirdly it's rapid slewing capability allows it to perform unique tasks, such as very low-overhead tiling of large error regions to search for transients. Here we discuss lessons learned and recent results from Swift's search for transients discovered by the Japanese "Monitor of the All Sky X-ray Image" (MAXI) near-all-sky X-ray survey instrument. We show how we applied lessons learned from 8 years of collaborating with MAXI, and show results from recent searches for optical/UV and X-ray counterparts of possible astrophysical neutrino sources, as triggered by the IceCube Neutrino Observatory. Finally we discuss searches for EM counterparts of LIGO sources with Swift, as we prepare for O3.