S T A N F O R D R A D I O A S T R O N O M Y I N S T I T U T E

(Report f rom Solar Institute)

R. N. BRACEWELL StanJbrd University, Stanford, Calif., U.S.A.

(Received 15 September, 1969)

Each day at noon the sun is scanned by the microwave spectroheliograph at Stanford and an automatic typewriter simultaneously types out the temperature as seen point by point by the scanning beam. The resulting spectroheliogram is then distributed immediately to interested users by teletypewriter via the Environmental Science Services Administration in Boulder, Colorado.

At the end of each month the daily maps are published in Solar Geophysical Data

by the Environmental Science Services Administration (ESSA), alongside a variety of other kinds of solar observation made elsewhere.

The angular resolution is 3 min of arc approximately and the wavelength is 9 cm. For a full description of the instrument see Bracewell and Swarup (1961). Further details of the published data are reported in the Descriptive Text issued annually by ESSA. One of the interesting things about the Stanford maps is the high degree of continuity in the data; in recent years publishable observations have been obtained over 98}o of the time. This results from the devotion of the observers J. H. Deuter and J. S. Rutherford. Analysis of recent data has been published by Riddle (1969). Possible research opportunities exist for visitors to Stanford, where several years of continuous data are available on punched cards in a uniform format suitable for computer processing.

At the present time, our principal activity is the construction of a new radio tele- scope with a resolution of 20 sec of arc with provision for polarization measurement, and it should be possible to turn this new instrument on the microwave active regions in another year or so. A report of the non-solar and solar work of the Stanford Radio Astronomy Institute, and references to publications, appears periodically in Astron. J.

References

Bracewell, R. N. and Swarup, G.: 1961, 'The Stanford Microwave Spectroheliograph Antenna, a Microsteradian Pencil Beam Interferometer', IRE Trans. Antennas Propagation 9, 22.

Riddle, A. C. : 1969, 'The Quiet and Slowly Varying Components of 9.1 cm Radio Emission during the Solar Minimum', Solar Phys. 7, 434.

Solar Physics 11 (1970) 161; �9 D. Reidel Publishing Company, Dordrecht-Holland