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© Baader Planetarium GmbH | 2021
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Manual: SunDancer II
8. As soon as the control box is powered, it automatically heats the filter up to the
necessary operating temperature. The display shows the temperature difference
to the set point; when the value 0 is shown, the filter is ready for operation. After
about five minutes, the temperature control has stabilized and you can fine-tune it
if necessary (see the following chapter "Filter calibration").
9. While the filter heats up, you can can insert an eyepiece, point the telescope at the
sun and observe. Due to the longer focal length caused by the telecentric, the sun
must be positioned exactly so that it can be seen in the eyepiece.
10. The micrometer screw tilts the etalon a maximum
of 3° from the optical axis. This has two functions:
(1) You can check the setting of the H-alpha line
without changing the temperature of the filter. To
do this, turn the micrometer screw sensitively and
without using force clockwise all the way in, as far
as it will go, and the H-alpha structures on the sun
should be clearly visible. The scale itself is only for
orientation, the stop does not have to correspond
to the 0 position.
(2) The micrometer screw is used for fast Doppler-event observations: For example,
if a prominence is moving quickly towards you, this may be enough for the H-alpha
line of that structure to shift so far into the blue part of the spectrum that you need
to readjust – this can be done quickly and easily with the micrometer screw or by
decreasing the temperature, which takes a little bit more time, but keeps the filter
in the ideal tilting angle.
Note:
After about three to five minutes the filter is in temperature equilibrium, before
that slight changes in the image are possible due to readjustment.
Note:
Observe the operating temperature of 0 to +40° C. At lower temperatures, the
filter must be thermally insulated so as not to overload the heating.
The Functions of the Temperature Control Box
Once the filter has been correctly calibrated to your
system (see chapter Calibrating the Filter on page 16),
you only need to connect the temperature control box
to the SunDancer II and then to a 12V power source.
The electronics will then bring the filter up to operating
temperature and automatically switch it off if it becomes
too warm.
The display of the control box shows the difference
from the factory set temperature. If your particular setup
requires a different operating temperature, please refer
to the chapter "Filter calibration" for instructions.
As soon as the display shows a stable "0", the filter is
ready for operation. When the telescope is pointed at the
sun, it takes about three to five minutes for the filter to
reach temperature equilibrium.
The micrometer screw can tilt the filter
to easily observe the blue wing of the
H-alpha-line
The display shows the temperature
difference to the ideal operating
temperature. Above shortly after po-
wering up, below once the operating
temperature is reached
The filter has a temperature sensor that switches off the heating if the filter becomes
too hot. In this case, the heating element is automatically switched off and will not
be reactivated until the filter has cooled down to 25 °C and the control box has been
disconnected from the mains.
To switch off, simply disconnect the temperature control box from the power source.
Changing the Operation Temperature
You can easily change the temperature of the filter and thus the position of its transmis-
sion window. Increasing the temperature shifts the maximum to the longer-wavelength
red wing of the H-alpha line; decreasing it shifts it to the blue wing in the shorter-
wavelength spectral range. A change of 10.0 units shifts the transmission maximum by
about 1 angstrom, which is also the maximum possible change.
Press the up arrow to increase the temperature or the down arrow to decrease it.
After a few seconds, the display changes to the current value and the filter is tempered
to the new setpoint (displayed as a deviation from the factory-set temperature value).
The new setpoint remains stored. So the next time you use it, the control box will
always show the last set value.
Note:
For quick observations in the blue wing of the H-alpha line, you can also use the
micrometer screw.
Using a Neutral Density Filter
The difference in brightness between the prominences and the solar disk is very large,
and it can be helpful, especially when observing with a large exit pupil, to screw a neu-
tral density filter into the eyepiece. This makes the structures on the solar disk more
visible to the eye, while the prominences become less
visible. You can achieve the same effect with a single
polarising filter that you screw into the eyepiece.
Then, as when used with a Herschel prism, the image
brightness can be adjusted by rotating the eyepiece
in its eyepiece clamp.
How strong the effect is depends on the respective
system as well as on your own eyes. In principle, the
image brightness can also be adjusted simply by
increasing the magnification; however, this presuppo-
ses that the air turbulence permits higher magnifica-
tions at all.
We recommend the following filters:
• Polarising filters: 1¼"
# 2408343; 2" # 2408342
• Neutral density filters (grey filters) ND 0.6 (T=25%): 1¼"
# 2458343; 2": # 2458321
• Neutral density filters (grey filters) ND 0.9 (T=12.5%): 1¼":
# 2458344; 2": # 2458322
Polarizing and Neutral Density Filters dim
the brightness, which may lead to better
visibility of details in the eyepiece
