I bit late but this only works for species with A. a working sense of vision, B. color receptors similair enough to human/eldrae to recognize that a sudden green star is unusual. For other color receptor cell sensitivity arrangements it may not be obvious. For optimal reasonable anti-stealthiness one may want to vary the laser light though varying patterns, frequencies, and intensities including those that encode prime sequences. And on the off the chance the the species in habitat ing the target species is completely blind, using a very light tap by a Cirys Superzorcher to temporarily mimic a second sun in their sky probably would get their attention but would also probably violate a bunch of explicitly or implicitly agreed arms limitations treaties so that’s probably a bad idea, maybe just land on their planet and start first contact directly that way in that case.