The tidal radius of M3 is about 38 arc minutes.
The center of the distribution of these features is offset about two arc minutes to the southwest.
Firstly, the sun is not a point, but has an apparent size of about 32 arc minutes.
"The direction of origin of the potential signal is known to within five arc minutes."
They are separated by 7 arc minutes on the sky.
It is approximately 2.7 arc minutes away from NGC 9.
The differences shown on the plot are in arc minutes.
A knowledge of the telescope's direction will then give the positions of the sources typically to within half an arc minute.
The cluster appears 18 arc minutes in size.
With the lowest power of 500x, the field of view was 3 arc minutes.