Plaskett Report for July 1929

Had it not been for a week of clear nights at the close of the month, there would have been a very low record for the month’s observing. As it was, there were 26 nights on which a total of 96 plates were secured with a total exposure time of 121.4 hours. The ten-year average shows 26 nights, 203 plates with total exposure 136.4 hours.

Approximately 15, 288 persons visited the observatory during the month.

Director J. S. Plaskett measured 15 spectrograms for interstellar calcium. Arranging stellar and interstellar velocities in various groups and computing the rotational coefficient and K term. Usual correspondence, etc.

Assistant Director W. E. Harper worked 5 nights securing 46 plates. Measured for radial velocity 27 plates. Put through a solution for the 1927 and 1928 observations of HR 5472 and additional work on changing velocity of systems. Gave one seminar talk.

Astronomer J. A. Pearce measured the velocity of calcium on eleven spectrograms. Occupied during the month with computations on the motions of interstellar calcium. Gave 1 staff talk on Rotation of the Galaxy.

Astronomer C. S. Beals worked 4 nights, obtaining 5 plates. prepared a paper on ‘The Nature of Wolf Rayet Emission’ for AAS meeting. Measured 4 plates of Wolf Rayet stars for absolute wave lengths. Tested new optical parts of ultra-violet spectrograph. Gave on seminar talk.

Computer S. N. Hill did computational and other work on B-type stars.

Assistant Astronomer R. O. Redman obtained 33 spectra (28 plates) on 7 nights. Measured 10 standard K spectra and from these and former measures calculated the probable errors in the K programme. Measured 39 plates for the K programme and 1 of Y Cygni. From radial velocities collected to date performed preliminary calculations with respect to galactic rotation in giant K stars.

Summer Assistant P. M. Millman worked 2 Saturday nights securing 3 plates, after showing visitors objects with telescope. Plotted star fields of faintB-stars. Tested out periods for binaries. Gave one seminar talk.

Assistant Astronomer A. Pannekoek secured 14 star spectra on 6 nights and 4 sky spectra at daytime. Other nights made photometric experiments. Theoretical work on stellar atmospheres and absorption lines.

Clerk-Stenographer Miss L. M. Blake handled correspondence, official reports, accounts, library assistance and typing of astronomical papers. Envelopes for spectrograms.

Instrument Maker Foreman T. T. Hutchison assisted in observing on 17 nights. Replaced broken wheel on dome and kept telescope in running order.