"occasionally observed" — Kollokationen-Wörterbuch Englisch

occasionally observed Kollokation
Automatische Übersetzung (wir garantieren seine Korrektheit nicht): od czasu do czasu zauważać
  1. observe Verb + occasionally Adverb
    Schwache Kollokation

    Also nowadays the lights are observed occasionally, they have been taken on movies and photographed.