Bibcode
Bethge, C.; Peter, H.; Kentischer, T. J.; Halbgewachs, C.; Elmore, D. F.; Beck, C.
Bibliographical reference
Astronomy and Astrophysics, Volume 534, id.A105
Advertised on:
10
2011
Journal
Citations
42
Refereed citations
38
Description
Aims: We introduce the Chromospheric Telescope (ChroTel) at the
Observatorio del Teide in Izaña on Tenerife as a new
multi-wavelength imaging telescope for full-disk synoptic observations
of the solar chromosphere. We describe the design of the instrument and
summarize its performance during the first one and a half years of
operation. We present a method to derive line-of-sight velocity maps of
the full solar disk from filtergrams taken in and near the He i infrared
line at 10 830 Å. Methods: ChroTel observations are
conducted using Lyot-type filters for the chromospheric lines of Ca ii
K, Hα, and He i 10 830 Å. The instrument operates
autonomically and gathers imaging data in all three channels with a
cadence of down to one minute. The use of a tunable filter for the He i
line allows us to determine line-shifts by calibrating the line-of-sight
velocity maps derived from the filtergram intensities with
spectrographic data from the Tenerife Infrared Polarimeter at high
spatial and spectral resolution. Results: The robotic operation
and automated data reduction have proven to operate reliably in the
first one and and half years. The achieved spatial resolution of the
data is close to the theoretical limit of 2 arcsec in Hα and Ca ii
K and 3 arcsec in He i. Line-of-sight velocities in He i can be
determined with a precision of better than 3-4 km s-1 when
co-temporal spectrographic maps are available for calibration.
Conclusions: ChroTel offers a unique combination of imaging in the most
important chromospheric lines, along with the possibility to determine
line-of-sight velocities in one of the lines. This is of interest for
scientific investigations of large-scale structures in the solar
chromosphere, as well as for context imaging of high-resolution solar
observations.
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