in 1822 he published the first of many double-star catalogues, the identifying numbers of which are still used today. struve's stars, however, are now often named in his honor (for example, struve 2398), whereas the original catalogue prefix was the greek letter sigma. in 1833 he moved to russia to set up the pulkovo observatory near st. petersburg, of which he was director until his retirement in 1862, when his son took over in the post. in total, friedrich struve produced 272 astronomical works and 18 children; his great-grandson otto, by contrast, produced 907 works but zero children.