I had captured 3 drift frames. The first had 41 Dra and SAO 9002 and was 30 seconds long. I had meant to produce longer ones but goofed on the setting of the EOS Utility timer. The 2 others were still 30 seconds and without bright stars. I chose the first image.
The Réduc software only accepts FITS and BMP files. So I converted, with IrfanView, the Canon RAW files to Windows BMPs.
Winging it, I loaded the drift image BMP into Réduc. Stared at the interface for a moment. Clicked the Drift Analysis button but, not surprisingly, got a calculation error. Noted the comp A and B buttons. Used them and again clicked the Drift Analysis button. Was prompted to set the view orientation. Recalled the drift was right to left during the session. So west was left. But I drew a blank with north. I chose north as up. The Reduction dialog appeared. I stared at it for a mo. Um. The θ value was 270. That wasn't what I was after... Sketched a Cartesian coordinate graph. 270 to the left... What was I looking for? What should I pay attention to?
Popped into the tutorial. Learned I was doing the basic steps OK. But could refine. Observe the Δ value. I decided to redo. Opened the file. Reduced the size of the (green) detection box, to 29 pixels. Set the start and end points. Hit the Drift button. In SkyTools, double-checked the view orientation. It helped being able to detect star TYC 04577-0964 1 in the field. Confirmed. North was down. OK. Everything working.
The Reduction dialog showed the Δ as -1.5.
Close enough. From an airplane.
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Just out of curiousity, I measured the angle in Visio using a screen capture... -1.5°. How about that!
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