Archives structure (rel. zu web-root)
YYYY... subdirectory according to the year of observation
Data format and file names
|... scanned sunspot drawing in the format JPEG
YYYYMMDD_hhmm...date and time of the observation
The images are saved with 8-bit grey scales and have a size of about 140 kB.
The file names correspond to the SOHO
file name convention for synoptic data.
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Although looking superseded by imaging technologies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 ennough 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
images for any positional measurements. We encourage you to work on the
original drawings which are accessible to guests of the observatory.
This online service began in February 2000 and is updated daily with the new drawing.
The complete archives of sunspot drawings since 1944 were digitized.
The Kanzelhöhe Observatory would like to thank Dr. Alfred Schroll and
DI Franz Vogler for their commitment to do the scanning of the drawings.
Austrian Academy of Sciences
has given financial support for the hardware.
- Date and Time of Observation
- Observation Conditions (Seeing, weather, observer, X and Y give the diameters of the
circle at time of observation - may change due to paper shrinking
- Physical Ephemeris of the sun and the correction angle DP
- Number of groups, spots...; as used for the
Sunspot Relative Numbers
- Alignment markings (spot's trace)
- Markings of Solar N and S (Rotation Axis, corrected for the misalignment DP
- Markings of the Solar Limb
- Spot group with Zürich classification
||A single pore or group of pores showing no bipolar configuration
||A group of pores showing bipolar configuration
||A bipolar group, one spot of which possesses a penumbra
||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 deg.
||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 deg.
||A very large bipolar or complex group; length > 15 deg.
||A large bipolar group containing no small spots between the main spots; length > 10 deg.
||A unipolar spot possessing a penumbra; diameter > 2.5 deg.
||A unipolar spot possessing a penumbra; diameter < 2.5 deg.
The Zürich Classification of sunspot groups. Four examples of each class are shown.
The scale at the bottom
indicates degrees of heliographic longitude. Details are given in e. g.
Bray & Loughhead, Sunspots, Chapman and Hall, 1964.