Solar Physics Division
Tokyo Astronomical Observatory
Mitaka, Tokyo, Japan
July 1, 1957
Daily Maps of the Sun
According to the CSAGI (Comite Speciale de 1'Annee Geophysique Internationale, Special Committee for the IGY) recommendation, daily maps of the sun will be made from 1957 July and mailed once a week.
The maps contain approximate positions of big spots, K2-3 flocculi, Hα dark filaments and prominences, and 5303 Å coronal isophotes.
The positions of the phenomena except the corona are corrected to 0h U.T.
The observations between 21h and 24h are written on the map of the next day.
For instance, 21h 10m on the map of the 21st means that the phenomena observed at 21h 10m on the 20th.
Times with parentheses show that they are uncertain.
As a complement, the data from the other observatories are added with parentheses, which are telephoned daily from the Radio Research Laboratory to our observatory through the interchange codes.
Explanation of the Map
The large spots are represented by full circles of 1, 2, and 3 mm diameter, corresponding to their relative dimensions.
At the upper left corner, the date and the relative sunspot number R are given.
The following lines give the hour and the origin of observations used to draw the map.
Chromosphere: The outer contours of the flocculi are taken from K2-3 spectroheliograph. The weakest flocculi are given by contours only and those of the more intense by roughly shaded. The brightest is finely shaded.
Flares: The position of a flare is marked with a square of 3 mm with a reference number. The filled squares indicate the observations made at our observatory, and the diamonds indicate those at the other observatories. For each flare, the times of beginning and ending, and the importance are given in a tabular form.
Corona: The brightness of the corona in 5303 Å is given by a five-step scale, in the form of radii outside the solar limb on the corresponding angles of position. The steps denote an intensity (Norikura scale) of 6-30 x 10-6, 31-70 x 10-6, 71-120 x 10-6, 121-180 x 10-6, and >180 x 10-6. For the coronal intensity under the threshold intensity or < 6 x 10-6, nothing is marked.