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Once only accessible in nearby galaxies, we can now study individual starsacross much of the observable universe aided by galaxy-cluster gravitationallenses. When a star, compact object, or multiple such objects in the foregroundgalaxy-cluster lens become aligned, they can magnify a background individualstar, and the timescale of a magnification peak can limit its size to tens ofAU. The number and frequency of microlensing events therefore opens a windowinto the population of stars and compact objects, as well as high-redshiftstars. To assemble the first statistical sample of stars in order to constrainthe initial mass function (IMF) of massive stars at redshift z=0.7-1.5, theabundance of primordial black holes in galaxy-cluster dark matter, and the IMFof the stars making up the intracluster light, we are carrying out a 192-orbitprogram with the Hubble Space Telescope called "Flashlights," which is nowtwo-thirds complete owing to scheduling challenges. We use the ultrawide F200LPand F350LP long-pass WFC3 UVIS filters and conduct two 16-orbit visitsseparated by one year. Having an identical roll angle during both visits, whiledifficult to schedule, yields extremely clean subtraction. Here we report thediscovery of more than a dozen bright microlensing events, including multipleexamples in the famous "Dragon Arc" discovered in the 1980s, as well as the"Spocks" and "Warhol" arcs that have hosted already known supergiants. Theultradeep observer-frame ultraviolet-through-optical imaging is sensitive tohot stars, which will complement deep James Webb Space Telescope infraredimaging. We are also acquiring Large Binocular Telescope LUCI and Keck-IMOSFIRE near-infrared spectra of the highly magnified arcs to constrain theirrecent star-formation histories.

Flashlights: More than A Dozen High-Significance Microlensing Events of Extremely Magnified Stars in Galaxies at Redshifts z=0.7-1.5