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ROYAL ASTRONOMICAL SOCIETY OF CANADA Standing Committee on Observational Activities Programme for Solar Eclispe of July 20, 1963 Bulletin No. 5 Basic Observation Programme May 4, 1963 Section C. Visual Observations This section of the basic observation programme covers visual observations made during the total phase either with the naked eye or with telescopic aiti and with the emphasis on drawings or sketches, supplemented by verbal descriptions of detail seen. Dark Adaptation. jt is common knowledge that our ability to see dim light is pro- portional to the length of tame that the "rod" cells of the eye's retina remain unstimulated. To see fine detail during the brief period of totality, the eye must first become dark adapted, a process that takes at least twenty minutes. The gradual darkening of the sky during the partial phase is not suflicient to produce the des- ired effect, and the following methods of dark adaptation are suggested, (1) The observer is blindfolded during the approach of totality. This rather drastic measure deprives him of the thflll of seeing the sudden transition front partial to total phase when the corona sinnes forth in all its beauty True, he can watch the end of totality and the subsequent partial phase but it is not as spectacular as the approach. (2) The observer can wear dark red goggles during the approach of totality, for it has been fohd that the rods are practically unstimulated by the red end of the spectrum. This method aflows activity during the period of adaptation. Care must still be taken to provide adequate protection for the eyes when looking directly at the sun. (3) The observer can wear a black patch over his "observing" eye, watching the approach of totality with the other and removing the patch only after the beginning of totality. This method is particularly, sqitable for those making telescopic observations for most observer invariably use the same eye at the eyepiece. 1. CORONA Regardless of the ztumbei of photographs taken, visual observations of the solar corona will be useful, for the human eye, if properly dark adapted, can see fine detail that is difficult to photograph without over-exposing other aretts. The problem, of course, in making visual observations is to record faithfully the detail that one sees - the shape and extent of the corona, the variations in intensity and to do this in a very limited period of time. The observer should not trust to memory but should complete his drawing from actual observation tharing the period of totality. This is a tall order and it is suggested that the observer practise before- hand, making drawings frdth. pro jected Slides of the solar corona. For the sake of uniformity it is suggested that a two inch circle represent the sun's disk. A verbal description, recorded immediately after totality, should supplement the drawing. As mentioned in Bulletin No. 4, at sun-spot minimum it is expected that the corona will have long equatorial streamers and short polar plumes. Observations can be made with the naked eye or with a telescope. The report form should give details of equipment used. The telescopic observer has the disadvantage that, since no filters are used during totality, he must be ready to stop a few seconas before the end of totality to avoid the possibility of injury to his eyes.