Sunspot Drawings

The daily Sunspot Drawings continue a long tradition of Solar Observation at Kanzelhöhe. Although looking superseded by imaging technologies they show their ability to give a quick overlook what is going on. The feature to inspect them without any displaying tool and the ease handling make them favourable for preselecting of periods to investigate but they are precise enough to be also used for deriving proper motions of sunspots. Nevertheless they are still used for deriving the Sunspot Relative Numbers.
Doing a Sunspot Drawing is very simple. We use a refractor (d/f = 110/1650 mm) on our patrol instrument, a projection lens enlarges the primary image to 25 cm diameter and focuses it to an attached drawing desk. Due to the folding of the light path the drawing is side reversed (i. e. E-limb is to the right). The sheet is rotated for azimuth = 0 points to sky North. The alignment is checked by tracing a spot's movement across the sheet due to the Earth's rotation. Although the precision of the scanning devices is quite high we do not recommend to use the scanned i mages for any positional measurements. We encourage you to work on the original drawings which are accessible to guests of the observatory.

Online-Archive

Explanation

Date and Time of Observation Observation Conditions: Seeing (sharpness and quietness), observer and comments about the weather situation Physical Ephemeris of the sun and the correction angle DP Number of groups, spots...; as used for the Sunspot Relative Numbers Markings of Solar N and S (Rotation Axis, corrected for the misalignment DP Markings of the Solar Limb Spot group with Zürich classification

Zürich classification

Class A:	A single pore or group of pores showing no bipolar configuration
Class B:	A group of pores showing bipolar configuration
Class C:	A bipolar group, one spot of which possesses a penumbra
Class D:	A bipolar group whose main spots possess penumbrae; at least one of the spots has a simple structure. the length of the group is generally <10°.
Class E:	A large bipolar group; the two main spots possess penumbrae, and have generally complex structure. Numerous smaller spots lie between the main spots. The length of the group is >10°.
Class F:	A very large bipolar or complex group; length >15°.
Class G:	A large bipolar group containing no small spots between the main spots; length >10°.
Class H:	A unipolar spot possessing a penumbra; diameter >2.5°.
Class J:	A unipolar spot possessing a penumbra; diameter <2.5°.
	Copied from Bray & Loughhead, Sunspots, Chapman and Hall, 1964.