Plaskett Report for March 1929

The month was considerably below the average for observing. On 17 nights 101 plates were secured with a total observing time of 93.3 hours. The ten-year average shows 153 plates on 16 nights with 104.8 hours observing. Both mirrors were resilvered during the month.

The number of persons visiting the observatory was approximately 433 in January, 300 in February and 656 in March. For the fiscal year April 1st, 1928 to March 31st, 1929 the total number of visitors was approximately 35,020.

Director J, S, Plaskett obtained 12 spectrograms on one night. Measured 18 for radial velocity. Designed and drew new camera and attachments for ultra-violet spectrograph. Usual administrative work and correspondence.

Assistant Director W. E. Harper worked 2 nights securing 22 plates. Measured for radial velocity 34 plates Silvered telescope mirrors. Making revisions to periods of binaries determined some years ago. Gave seminar talk

Astronomer J. A. Pearce obtained 39 spectrograms on 6 nights. Measured 43 spectrograms for radial velocity. Gave 1 seminar talk. Considerable time was spent on the classification of B-type spectrograms.

Astronomer C. S. Beals obtained 5 plates on 3 nights. Searched literature on the subject of radiation pressure and its connection with Wolf Rayet stars. Prepared two sections of a paper on the origin of the Wolf-Rayet bands. Gave on seminar talk. Nake some experimental tests of photographic spread using different colour filters.

Assistant Astronomer R. O Redman obtained 23 plates for the K programme on 5 nights. Measured 14 spectrograms of K stars. Reduced these and determined wave-lengths of about 70 lines in each of first 6 and about 45 in each of the remaining 8.

Computer S. N., Hill remeasured for radial velocity 28 spectrograms of binary B-star HD 32990. Obtained period of HD 32990. Calculated phases of 52 Mt. Wilson and 32 Victoria observations of HD 32990 and plotted velocities on graph for Mt. Wilson Observatory. Computations of first part of least-squares solution of orbit of above star.

Senior Clerk-Stenographer L. M. Blake did library assistance. Envelopes for spectrograms obtained. Correspondence, reports, accounts. Typing articles for publication.

Instrument Maker Foreman T. T. Hutchison assisted in observing on 6 nights. Prepared mirror for silvering and kept telescope in running order