We had a campaign of observing the annular solar eclipse on 2012 May 21 by naked eye through eclipse eyeglasses to determine the limit line of annularity. As a result, we had about 15,000 reports through our website. In addition there were many observation groups for which about 30,000 people in total participated in the observations. The overall result was that the limit we observed by naked eye through eclipse glasses coincided with a prediction that took into account the lunar limb irregularity within the error of ±500 m. This error of the limit line location corresponds to about ±200 km of the radius of the Sun.

ABSTRACT
1. INTRODUCTION
2. NORTHERN LIMIT OF ANNULARITY
3. LUNAR LIMB PROFILES
4. SOLAR RADIUS
5. LIMIT LINE OBSERVATION CAMPAIGN
REFERENCES

• Mitsuru Soma(National Astronomical Observatory of Japan)