One way to get a feel for what a arc second is in actual distance in the sky is to put a bright star in the center of your field of view then turn off the clock drive on your telescope for however many seconds and the distance that the center of your field of view has moved is however many arc seconds or arc minutes you had the clock off. clear skies ! : I have looked at many deep sky resources and they often refer to the size of galaxies and nebula in 'arc-seconds' but I am unable to find any resources that explain how to fit the 30 arc-seconds wide object in the book on to a star chart to get a feel for its size.

: Does anyone have any URLs or Info on this?