Plaskett Report for April 1929

The month was about the average for observing as 122 plates were secured on 15 nights with 103.6 hours observing time. The ten-year average is 17 nights, 136 plates with 100.7 hours total observing.

Approximately 840 persons visited the Observatory during the month

Director J. S. Plaskett observed one night securing two plates. Measured 17 plates for radial velocity. Collation and preparation of material for galactic rotation. Handled the usual correspondence and administrative work.

Assistant Director W. E. Harper observed 3 nights securing 47 plates. Measured for radial velocity 30 plates. Some time spent in improving periods of binaries previously investigated.

Astronomer J. A. Pearce observed on 4½ nights obtaining 32 spectrograms. Measured 59 plates. Gave one seminar talk on ‘Moving Clusters’. Compiled observing catalogue of 506 O-B5 stars north of the equator and fainter than 7.50. Limit is 11.0. Some work on statistics of B class stars.

Astronomer C. S. Beals observed 3 nights obtaining 19 plates. Measured 15 plates of Wolf Rayet stars for band wave-lengths and band widths. Made a  number of determinations of photographic spread in the ordinary and usual regions of the spectrum. Gave one seminar talk

Assistant Astronomer R. O. Redman finished work on wave-lengths of lines in K type spectra as photographed with 1SS camera. Measured 40 plates and reduced same using these wave-lengths. Obtained 22 plates on 3½ nights. gave one seminar talk.

Assistant Astronomer A. Pannekoek assisted in observing on two nights to get acquainted with the working of the telescope. Prepared a list of stars whose spectra are to be obtained for the investigation of the absolute intensities of their lines. Made some accessory devices for that purpose.

Computer S. N. Hill did a least-squares solution of binary star HD 32990. Least-squares solution of same star combining 36 Victoria and 55 Mt. Wilson observations. Work in connection with preparation of faint B-type star programme.

Senior Clerk-Stenographer L. M. Blake handled the usual correspondence, accounts, reports and typing of astronomical papers., seminar talks and radio talks. Library assistance. Envelopes for 122 spectrograms. Proof-read Volume IV, Number 12.

Instrument Maker Foreman T. T. Hutchison assisted in observing on 12 nights. Kept telescope in running order.