Volume 49 number 1 (2021)
(Abstract only) In an ideal world, we could image sizescales as small as the distance between the Earth and the Moon. However, even the highest resolution astronomical imaging facililities, like the Event Horizon Telescope, could only do so out to distances less than 100 parsecs (326 light-years) from Earth. However, since light travels from the Earth to the Moon in about 1.3 seconds, rapid variability can probe small distances across the entire Universe—if your source is bright enough and you have a good setup. I will discuss recent rapid-variability results from relativistic jets launched by stellar-mass black holes that are feasting on the envelope of nearby stars. These results demonstrate the power (and pitfalls) of rapid variability (milliseconds to minutes). I will also discuss some of the equipment that astronomers are using to make such measurements—especially CMOS/sCMOS detectors whose useful features include minimized deadtime due to quick readout, low readout noise, and windowing.