Past and Present of the Synoptic Observations of the Sun at the National Astronomical Observatory of Japan

The National Astronomical Observatory of Japan has a history of about 100 years of regular synoptic solar observations. It started with Ca K spectroheliographic and white-light imaging observations, and shortly afterward, the counting of sunspots was started. Current imaging observations are being carried out in the Hα line, the Ca K line, the G-band, and the green continuum. In addition, the NAOJ has a history of more than 30 years of magnetic field measurements, and now we are conducting full-Sun spectropolarimetry observations. Most of the historical photographic and hand-drawn data have been digitized and are now open at our web site as well as recently obtained data. Here we introduce our data to promote the collaboration in the long-term solar activity study.