 |
22. Plot of Declination Drift
Notes: The sky was clear and there was no breeze. There was a first quarter moon in the southwest. We attempted to track Antares near the southern meridian without correction for right ascension or declination. Over 10 minutes, we could see no drift on the fine grid in PHD. But it is difficult for the eye to resolve a change of one or two pixels in a star, so we plotted the log file of a guiding session with DEC turned off. The nominal target was M101, the Pinwheel Galaxy. The blue line is RA, the red DEC. The horizontal axis is time in seconds; the vertical axis is pixels. There is clearly a lot of drift. The apparent southward drift of the guide star shows that the error in alignment to the celestial pole is to the west. Since the adjustment knobs for azimuth are a little crude, it appears that the correction for DEC drift will have to be done by guiding. Zoom in/out with ⌘↑(+/-) (Mac), ctrl (+/-) (PC).