Stellar Photometric Observations at Hα Through a Narrow-Band Interference Filter

Hugh E. Butler
1976 Symposium - International astronomical union  
The paper describes the results of stellar photoelectric observations made with a small telescope and a 3 1/2 Å wide filter centred at Hα.The method proved to be a sensitive one for detecting change in the spectrum but did not allow differentiation between changes in the Hα profile and wavelength changes due only to the Doppler effect. It was possible, however, to recognise and qualitatively to eliminate the Doppler changes due to the Earth's Annual Motion.Of ten Be stars examined three,
more » ... h in strong emission, showed little change over the periods of observation, the longest of which was 9 months. The other seven showed large and random changes.Warnings are given about the difficulty of tuning such a filter exactly to Hα and the need to monitor accurately the filter for long term changes in passband and throughput.
doi:10.1017/s0074180900011177 fatcat:x436rt7csrcatgcngezowusfei