Plaskett Report for February 1922

The observing weather for this month has only been fairly good and would have been very poor except for a run of good weather at the end of the month. There were obtained 134 spectra on 14 nights or parts of nights. During the month the mirror was resilvered and this, owing to unforeseen difficulties, would have prevented observing on two nights which were, however, cloudy.

[A note on the re-silvering of the 72-inch mirror. As silver tarnishes fairly quickly the mirror needed to be re-coated every 4 months or so. The spectrograph would first be removed and then the mirror cell lowered and the mirror removed to the silvering cart. The old coating would be removed. Dams were setup to keep the silvering solution on the mirror. The ‘magic solution’ used for silvering including the use of grain alcohol and rock candy! The solution would be poured onto the mirror and a light held underneath the mirror. As the silver deposited out of the solution the light would become fainter. At the appropriate faintness, hence thickness of coating, the solution would be removed. It would be until the late 1940’s that the mirror would start to be coated with aluminum., Ed.]

Director J. S. Plaskett obtained 21 spectrograms on 2 nights and measured 35 spectrograms for radial velocity. Prepared and delivered two lectures in Vancouver. Made further tests of the ultraviolet spectrograph and attended to the usual administrative work and correspondence work.

[Plaskett was in Vancouver to address a meeting of the B.C. Academy of Science. As reported in the newspaper he stayed the Hotel Vancouver., Ed.]

Research Astronomer W. E. Harper obtained 60 spectrograms on 3 nights. Measured 23 spectrograms for radial velocity and estimated line intensities on 235 spectrograms for determination of absolute magnitude. Spent some time in estimating spectral types and part of two days in assisting the silvering of the mirror.

Astronomer R.K Young obtained 37 spectrograms on 6 nights and estimated spectral types of about 500 spectrograms. He measured 10 spectrograms for radial velocity. Prepared and delivered a lecture before the Victoria Chapter of the Royal Astronomical Society of Canada. Assisted in the silvering of the mirror on two days.

[A newspaper article noted that “the main address of the evening on the spectrograph, by Dr. R. K. Young”. The article also states “Dr. Young will discuss it’s construction and in as simple language as possible”., Ed.]

Article in the Daily Colonist, Feb. 25, 1922

Assistant Astronomer H. H. Plaskett obtained 16 spectrograms on 2 nights. Worked on the determination of the temperature of O-type stars from their spectrum by means of various theories of ionization. Began observations and calculations for determining curvature corrections for one, two and three prism spectrographs. He prepared the manuscript for Volume I, Number 30 of the PDAO. Finally he prepared and gave a short talk to the RASC.

[In fact. Harry Hemley Plaskett’s talk was to the annual meeting of the Victoria Chapter of the RASC. J. S. Plaskett, R. K. Young also spoke at that meeting, Ed.]

Report on the Annual Meeting of the RASC

Clerk-Stenographer Miss H. R. Keay in addition to the usual correspondence and accounts, proof of PDAO Volume I, Numbers 26-29 was read, two articles for the Daily Colonist were typed, the plates obtained during the month were entered and recorded and some back correspondence filed.

Instrument Maker Foreman T. T. Hutchison assisted with observing on 11 nights. Usual work in keeping telescope and dome in working order. Wiring ultra-violet spectrograph for temperature control