The following is a list of all known ground-based solar observatories that operate on a routine basis to obtain scientific observations of the sun. The observatories are sorted according to longitude, from east to west. There 100 observatories on the list and 180 separate "instruments". ... Telescope: BiSON site . ... Culgoora Solar Observatory . ... Instrument: Solar Flare Telescope . ... Nobeyama Solar Radio Observatory . ... Telescope: RSTN Site (Radio Solar Telescope Network) . ...