Plaskett Report for September 1927

The observing weather was much below the average for September. While observations were secured on 18 nights yet most of these were so poor that a total of only 106 plates were secured as against an eight-year average of 177. The number of hours actual observing was 103.6 against the September average of 150.3.

Director J. S. Plaskett measured 8 plates. Worked on rotation of galactic system using fainter B-type stars. Made some preliminary measures for the colour index of ν Sagittarii. Prepared and gave seminar talk in interstellar medium

Assistant Director W. E. Harper worked 3 nights obtaining 16 spectra. Measured for radial velocity 37. Determined the orbit of HR 8210 and wrote up for publication. Gave seminar talk on Absolute Magnitudes of Early Type Stars.

Research Astronomer H. H. Plaskett worked 1 night obtaining 10 spectra. Measured for radial velocity 37. Worked on investigations on theory of stellar chromospheres and computations for the temperature determination of Z Andromedae. Prepared and gave seminar talk on the Determination of Absorption Line Intensities in Stellar and Solar Spectra.

Astronomer J. A. Pearce observed 3 nights obtaining 25 spectra. Measured 21 spectrograms for radial velocity. Completed an article for publication entitled “Graphical Solutions of the Pole-Star-Apex Triangle”. Worked on the orbit of the double-lined B-type binary HD 176853

Astronomer C. S. Beals studied methods of determination of absolute magnitude and parallax of stars, stellar temperatures and theory of band spectra. Measured oxygen lines on high dispersion laboratory spectra in the Region 4330 – 4800 to obtain accurate wave lengths for radial velocity work.

Astronomical Computer S. N. Hill computed proper motion and position angle of proper motion vector for B-type stars. Plotted graph, angle pole apex for B-type stars and measured and reduced for radial velocity 6 B-type spectrograms.

Senior Clerk-Stenographer Miss L. M. Blake handled the usual correspondence, accounts, reports, plates and astronomical typing. Typed and prepared for printer Volume IV, Number 4. Work on catalogue of mailing list.

Instrument Maker foreman T. T. Hutchison assisted in observing on 12½ nights. Adapted a guiding arrangement for ultra-violet spectrograph. Put new spider lines in measuring engines.

Temporary Assistant R. M. Petrie observed 4 nights, securing 27 spectrograms. Measured 17 players for radial velocity. Completed orbit of HR 6611. Worked on orbit of HR 6979. Transformed coordinates.

Temporary Assistant P. M. Millman observed 3 nights obtaining 21 plates. Measure 35. Worked on the periods of HD 176818 and HD 176819 and on orbit of HD 176819.

Temporary Assistant H. Zanstra worked on 4 nights obtaining 7 spectra of which 1 was a long exposure. This was in continuation of the research on planetary nebulae.