Kappa Bootis is my third double star observation from the night of the 1st May (see my previous post for a discussion of this). Here is my image:-
This was a 5s exposure at ISO 1600 on a Nikon D90 at the prime focus of a 140mm Maksutov Cassegrain (an Orion OMC-140). The picture can be better seen by 'clicking' on it. The image is being viewed at full scale (in other words it has not been binned up). Kappa 1 and 2 Boo are marked and Kappa 1 magnitude is 6.69 whereas Kappa 2 is a Delta Scuti variable ranging in brightness from 4.50 to 4.58. The image scale is 0.5859 arcseconds per pixel and this is a 1200x1200 pixel crop of the original.
My method for orientating the image has been described in my last post. Using this I have made some measurements of the separation and position angle (PA) of Kappa Boo (for a discussion of PA and how it is measured please again refer to my previous post). A couple of measurements of the separation gave me 23.60 and 23.02 pixels. This averages to 23.31 pixels and, at 0.5859 arcseconds per pixel, this is 13.7 arcseconds. Again a couple of measurements of PA gave 233.6 and 235.6 degrees which averages to 234.6 degrees. The published separation and PA for this double star is 13.5 arcseconds and 235 degrees, so in very good agreement.
All text and images © Duncan Hale-Sutton 2024
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