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Solar Disk Integrated Teleskop
Das „Solar Disk Integrated (SDI) Teleskop“ wird das Licht
der räumlich unaufgelösten Sonnenscheibe mittels einer
Glasfaser in den PEPSI Spektrographen füttern. Dessen
Zweck ist einerseits eine externe Kalibrationsquelle für
den höchsten Auflösungsmodus von PEPSI, andererseits
werden kontinuierlich Spektren der Sonne aufgezeichnet
um die Variationen von Spektrallinien-Bisektoren im Verlauf des Aktivitätszyklus zu erhalten.
STELLA Echelle Spektrograph
Der STELLA Echelle Spektropgraph (SES) ist ein moder-
Fig. 4: The prototype of the PEPSI image slicer at work in the STELLA spectrograph.
ner Weißpupillen-Spektrograph mit einer moderat hohen
spektralen Auflösung von 55.000 und einem festen Wellen-
The pressure chamber, housing the spectrograph, is
längenbereich von 390 bis 900 nm, der mit einer einzigen
currently passing the final tests of the temperature
Belichtung erhalten wird. Der Spektrograph ist auf einem
and pressure stabilization loop, before the first optical
optischen Tisch in einem temperaturstabilisierten Raum
components can be moved in.
aufgebaut und mit dem Teleskop mittels einer 15 m langen
The limiting magnitude of the spectrograph will be
Lichtleitfaser verbunden. Die Faser hat einen Kerndurch-
around V = 20 mag in the 120,000 resolution mode
messer von 50 um mit einer Mikrolinse auf der Einkoppel-
with a S/N of 10:1 assuming one hour integration time
seite, welche eine freie Apertur am Himmel von 2,8“ ergibt.
at 0.7” seeing. The main scientific goal is to measure
magnetic fields on the surfaces of stars like our Sun. In
gaining knowledge about the magnetic fields on other
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Calibration 600 µm fiber (ThAr
Entrance diaphragm 5''-20''
at the focal plane of F/15
+FF)
on a moving stage
stars, we hope to better understand our Sun, how it
was formed and what role our planetary system played
and will play.
Solar Disk Integrated Telescope
Collimator F=203mm
Glan-Thompson calibration
prism 30mm mount
depolarizer
Swinging arms with
rotary stages
Wedge depolarizer 25.4mm mount
The Solar Disk Integrated (SDI) Telescope will feed
Disk-unresolved solar light to the spectrograph using
a fiber connection via the PEPSI calibration unit. Its
aim is to provide an external comparison source for
blue plate
Calibration retarder 25mm mount
red plate
Calibration retarder 25mm mount
the UHR mode of PEPSI and its long-term stability,
red plate
Science retarder 25mm mount
and at the same time to monitor the Sun for measur-
reserved
Reserved retarder
ing line-bisector variations over an entire activity cycle.
The highest spectral resolution mode of 300,000 will
Wollaston prism 30mm mount
ADC
Camera F=34mm
3 mm
Inclined mirror with 200 µm
fibers immersed
14 mm
be used for this task.
STELLA Echelle Spectrograph
The STELLA Echelle Spectrograph (SES) is a modern
white pupil spectrograph with a moderately high spectral resolution of 55,000 and a fixed wavelength format
of 390 nm to 900 nm which is obtained in a single exposure. The spectrograph is bench mounted in a tem-
Fiber viewing CCD
camera FOV=20''
with step-gradient
filter linear stage
perature stabilized environment, and connected to the
telescope with a 15 m long optical fiber. This fiber has
a core diameter of 50 um with a microlens attached to
the entrance side, which yields an entrance aperture
of 2.8” on the sky. The detector in use is a 2k x 2k E2V
Fig. 3: Schematic sketch of the PEPSI polarimeter.
CCD.
79