LMU Munchen operates an astrophysical observatory on Mt. Wendelstein with two telescopes (2m and 40cm, Refs.1-3) and five instruments (three imagers4-8 and two spectrographs9, 10) for night time observations. The observatory offers service observations for the astronomy groups of the LMU physics department as well as for their collaborators. Staff and student observers have to be able to adjust observation scheduling to a wide range of observing conditions (often changing several times during an individual night) meeting the demands of very different observation project constraints (background limited, seeing limited, time limited etc.). To meet these requirements we adapted a free bug tracking software (https://www.redmine.org) which was already in place for observatory operations and software development. The tool enables easy communication between, and progress documentation for observers and observing projects leads with only very little administration overhead. Here we describe how we set up the tool and its impact on observations quality.
The Ludwig-Maximilians-Universität München operates an astrophysical observatory on the summit of Mt. Wendelstein which was equipped with a modern 2m-class robotic telescope in 20111-3. One of the two Nasmyth ports is designed to deliver the excellent (< 0.8” median) seeing of the site for a FoV of 60 arcmin2 without any corrector optics at optical and near infrared (NIR) wavebands. This port hosts a three channel imager whose design was already presented in Lang-Bardl et al. 2010.4 It is designed to efficiently support observations of targets of opportunities like Gamma-Ray-bursts or efficient photometric
redshift determination of sources identified by surveys like PanSTARS, Planck (SZ) or eROSITA. The covered wavelength range is 340 nm to 2.3 microns. The camera provides standard broadband filters (Sloan, Y, J, H, Ks) and 5 narrowband filters (OI, Hα, SII, H2, Brλ). The narrowband filters will enable deep studies of star forming regions. We present the final design of the camera, the assembly and alignment procedure performed in the laboratory before we transported the instrument to the observatory. We also show first results of the achieved on sky performance concerning image quality and efficiency of the camera in the different filter passbands.
LMU Munchen operates an astrophysical observatory on Mt. Wendelstein1. The 2m Fraunhofer telescope2, 3 is equipped with a 0.5 x 0.5 square degree field-of-view wide field camera4 and a 3 channel optical/NIR camera5, 6. Two fiber coupled spectrographs7-9 and a wavefront sensor will be added in the near future. The observatory hosts a multitude of supporting hardware, i.e. allsky cameras, webcams, meteostation, air conditioning etc. All scientific hardware can be controlled through a single, central "Master Control Program" (MCP). At the last SPIE astronomy venue we presented the overall Wendelstein Observatory software concept10. Here we explain concept and implementation of the MCP as a multi-threaded Python daemon in the area of conflict between debuggability and Don't Repeat Yourself (DRY).
A modern 2-m telescope is in comissioning phase at Wendelstein Observatory since late 2013. In order to make full use
of good seeing conditions in Wendelstein, many measures were taken to reduce the image aberration to get the best image
quality. Due to its fast primary mirror, the telescope image quality depends critically on the secondary mirror alignment.
Thus a scheme of quick and accurate alignment of the secondary mirror is desired for the telescope system. We will
utilize a Shack-Hartmann wavefront sensor (SHS) to optimize the alignment for a basically well aligned telescope system.
The principle of the image aberration measurement using SHS is shortly re-introduced with this paper. Merit function
regression method can be used to align the secondary mirror of the telescope system using Zernike coefficients derived
from the reconstructed wavefront. The principle of merit function regression method is described in this paper. Optical and
mechanical layout of this telescope alignment system is also shown. A temperature stabilized box for SHS was designed
to keep the wavefront measurement precision of a commercial SHS system in the harsh conditions of an observatory site.
Mechanical design and temperature control system of the temperature stabilized box are also illustrated. The deviation of
the temperature is within 0.04 degree from the first test of the temperature stabilization experiment, which is good enough
to decrease the wavefront measurement error produced by environmental temperature variation.
The commissioning of the telescope and its first instrument, a Nasmyth port mounted 0.5 degree CCD mosaic imager, started in November 2013. We will report about the results of astronomical tests of the integrated system including the achieved optical quality across the field of view, pointing and tracking quality and operational experiences with the observatory system. The special design features of this alt-az telescope are its compactness and the low-ghost wide field optics (0.7o f.o.v. diameter), and we will briefly report on the lessons learned especially for these special features. We will present an outlook on the further commissioning including the additional instruments which are all under construction or already finalized.
LMU München operates an astrophysical observatory on Mt. Wendelstein1 which has been equipped with a modern 2m-class telescope2, 3 recently. The new Fraunhofer telescope has started science operations in autumn 2013 with a 64 Mpixel, 0:5 x 0:5 square degree FoV wide field camera,4 and will successively be equipped with a 3 channel optical/NIR camera5 and 2 fibre coupled spectrographs (IFU spectrograph VIRUSW6 already in operation at the 2.7 McDonald, Texas and an upgraded Echelle spectrograph FOCES7, 8 formerly operated at Calar Alto oberservatory, Spain). All instruments will be mounted simultaneously and can be activated within a minute. The observatory also operates a small 40cm telescope with a CCD-camera and a simple fibre coupled spectrograph for students lab and photometric monitoring as well as a large number of support equipment like a meteo station, allsky cameras, a multitude of webcams, in addition to a complex building control system environment. Here we describe the ongoing effort to build a centralised controlling interface for all hardware. This includes remote/robotic operation, visualisation via web browser technologies, and data processing and archiving.
Ludwig-Maximilians-Universitat Munchen operates an astrophysical observatory on the summit of Mt. Wendelstein 1 which has been equipped with a modern 2m-class telescope.2-4 The new Fraunhofer telescope is designed to sustain the excellent (< 0:8" median) seeing of the site [1, Fig. 1] over a FoV of 0:2 deg2 utilizing a camera built around a customized 64 MPixel Mosaic (Spectral Instruments, 4 × (4k)2 15μm e2v CCDs). The Wendelstein Wide Field Imager5 had its commissioning in the lab in the course of the last few months and now waits to see first light on sky in the near future, i.e. when telescope commissioning allows to test science instruments.
In November and December 2010 we successfully commissioned a new optical fibre-based Integral Field Unit
(IFU) spectrograph at the 2.7m Harlan J. Smith Telescope of the McDonald Observatory in Texas. Regular science observations commenced in spring 2011. The instrument achieves a spectral resolution of λ/Δλ = 8700 with a spectral coverage of 4850Å – 5480Å and a spectacular throughput of 37% including the telescope optics.
The design is related to the VIRUS-P instrument that was developed for the HETDEX experiment, but was modified significantly in order to achieve the large spectral resolution that is needed to recover the dynamical properties of disk galaxies. In addition to the high resolution mode, VIRUS-W offers a stellar population mode with a resolution of λ/Δλ = 3300 and a spectral coverage of 4340Å – 6040Å. The IFU is comprised out of 267
150 μm-core optical fibers with a fill factor of 1/3. With a beam of f/3.65, the core diameter translates to 3.2" on sky and a large field of view of 105" x 55" that is ideally suited to study the bulge regions of local spiral galaxies. The large throughput is due to a design that operates close to the numerical aperture of the fibers, a
large 200mm aperture refractive camera with no central obscuration, highly efficient volume phase holographic gratings, and a high-QE CCD. We will discuss the design, the performance and briefly present an example for the very up-to-date science that is possible with such instruments at 2m class telescopes.
Due to the exposed location of the Wendelstein observatory on the steep summit of mount Wendelstein no road exists to
transport telescope components and heavy equipment to the observatory in order to install the new 2m Fraunhofer
Telescope Wendelstein (FTW) in its new dome. A two step installation concept was therefore followed to mitigate any
risks that essential hardware would not work once installed on the mountain.
This paper reports on the telescope factory assembly and tests, including on-sky tests, which were performed in early
summer 2011 at the factory site to make sure, that the telescope and all essential subsystems are working properly before
the telescope would be installed on the mountain. The telescope was disassembled again to be transported to the
mountain in summer. Lifting of all structural subsystems and the optics up to the mountain observatory with the help of a
heavy lift helicopter will be presented in detail, also looking at specific design drivers, logistic aspects and special tools
for installation of the telescope and its mirrors in its new dome. Handling and transport concept for the M1 mirror
installation, which also will have to be used when the mirror is disassembled for recoating, are presented. Up to end of
2011 the telescope installation and pre-alignment could be completed including first on-sky tests. The system will
undergo a detailed performance test campaign in the first halve of 2012. Current performance results of these
commissioning activities will be reported.
The integration of the 2m Fraunhofer telescope started in August 2011 at the Mt. Wendelstein observatory. The
logistics of the project are a key problem of the integration as the observatory has no road access. All large
or heavy components inlcuding the primary mirror were successfully delivered by helicopter. Meanwhile, they
are integrated in the telescope. The special design features of this alt-az telescope are its compactness and the
low-ghost wide field optics (0.7 deg. f.o.v. diameter).
We will briefly report on tests of the building and of the telescope system before the telescope moved to the
mountain. The integration at the observatory and the first astronomical performances tests of the telescopes are
discussed, and a brief update on the status of its instruments is presented. We comment on the cleaning and
recoating strategy for the primary mirror based on sample tests.
Ludwig-Maximilians-Universitat Munchen operates an astrophysical observatory on the summit of Mt. Wendelstein1
which will be equipped with a modern 2m-class, robotic telescope. The plan is to operate one of the most
efficient robotic 2m telescopes in Europe in order to offer optimal scientific opportunities for our researchers
and maintain highest standards for the education of students. The 2m Fraunhofer telescope in its new 8.5m
dome has a modern, very compact alt.-azimuth design. Two Nasmyth ports will harbor a wide-field camera
(WWFI2), a medium field multi-channel camera (3kk3), a low resolution IFU spectrograph (VIRUSW4) and a
high resolution spectrograph (upgraded FOCES5). All instruments will be simultaneously ready for remote or
robotic observations. The telescope is designed as a 3-mirror f/7.8 system and should maintain the excellent
(< 0.8" median) seeing of the site1 over a field of view (f.o.v.) of 0.7 deg diameter with a field corrector for the
wide field port at optical wavelength. The second port provides a f.o.v. of 60 arcmin2 without any corrector
optics. It is optimized for simultaneous optical and NIR imaging as well as field spectroscopy and echelle high
resolution spectroscopy over the full optical wavelength regime.6 Here we present the design of the telescope as
well as the scope and projected time line of the overall project.
The Ludwig-Maximilians-Universit¨at M¨unchen operates an astrophysical observatory on the summit of Mt.
Wendelstein1 which will be equipped with a modern 2m-class, robotic telescope.2 One Nasmyth port of the new
Fraunhofer telescope is designed to deliver the excellent (< 0.8" median) seeing of the site [1, Fig. 1] for a smaller
FoV of 60 arcmin2 without any corrector optics at optical and NIR wavebands. Thus, it will be optimized for
fast multi-wavelength follow-up observations of targets of opportunities (e.g. Gamma-Ray-bursts) or efficient
photometric redshift determinations of huge numbers of galaxy clusters identified in optical (PanSTARRS), SZ
(Planck) or X-ray (eROSITA) surveys. We present the design of a compact 3 channel camera which serves these
science requirements, built partly from commercially available Fairchild-2k optical CCD3 cameras (Apogee),
coupled with small Bonn Shutters,4 and mounted on commercial high precision linear stages for differential
focusing. A specially designed beam-splitter system maintains the high optical quality. The NIR camera is built
in cooperation with the Institute for Astronomy in Hawaii. The combined operation of this camera with two
spectrographs at the same telescope port has already been presented at SPIE 2008.5
Ludwig-Maximilians-Universit¨at M¨unchen operates an astrophysical observatory on the summit of Mt. Wendelstein1
which will be equipped with a modern 2m-class, robotic telescope.2 One Nasmyth port of the new
Fraunhofer telescope is designed to sustain the excellent (< 0.8" median) seeing of the site [1, Fig. 1] over a FOV
of 0.2 deg2 utilizing three-element transmissive field corrector optics for optical wavebands. It will be equipped
with a camera built around a customized 64 MPixel Mosaic (Spectral Instruments, 4 × (4k)2 15μm e2v CCDs).
TheWendelsteinWide Field Imager has two filter wheels with eight slots each (SDSS3 [ugriz] + eight still free)
as well as two off-axis guiding units (two FLI Microline with 2k Fairchild CCDs on differential focus stages). A
Bonn Shutter4 ensures high precision photometric exposures. An option to either insert a low dispersion grating
(for field spectroscopy) or support a wave front sensor probe allows for further expansion of the camera. EMI-safe
housing has to overcome the emission of a close by 0.5MW radio station. Special care has been taken to design
a very low ghost budget of the overall system to allow for low-surface brightness applications (e.g. weak lensing
The Ludwig-Maximilians-Universitat Munchen operates an observatory on the summit of Mt. Wendelstein in
the Bavarian alps which will be equipped with a modern 2 m-class, robotic telescope. We did extensive site
evaluations and started various monitoring programs on transmission, extinction, and seeing. Implementation
and results of these monitorings are reported. We further present our strategy to prepare the observatory for
this major upgrade, including hardware installations (besides the telescope), network and software infrastructure
upgrades, as well as improvements in the observatory operations. We aim at most efficient observations in a
"low-person-power" situation on a site which allows only partial robotic operations. The basic telescope design
and the strategy for its first generation of instruments are briefly discussed.
The design of a multi-instrument Nasmyth port for a 2m class telescope, located near Munich, Germany is
presented in this paper. A three channel optical and infrared camera will be located at this Nasmyth focus
together with an IFU spectrograph, a high resolution Echelle spectrograph, and a Shack-Hartmann sensor for
instrument alignment. Fast switching between the instruments and compact design in a small dome are boundary
conditions of the project.
Precise guiding and acquisition is made possible for all instruments. Calibration sources are fed to the fiber
coupled instruments using a built in telescope simulator.
The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) will measure baryonic acoustic oscillations, first discovered in the Cosmic Microwave Background (CMB), to constrain the nature of dark energy by performing a blind search for Ly-α emitting galaxies within a 200 deg2 field and a redshift bin of 1.8 < z < 3.7. This will be achieved by VIRUS, a wide field, low resolution, 145 IFU spectrograph. The data reduction pipeline will have to extract ≈ 35.000 spectra per exposure (≈5 million per night, i.e. 500 million in total), perform an astrometric, photometric, and wavelength calibration, and find and classify objects in the spectra fully automatically. We will describe our ideas how to achieve this goal.
We present the design of a compact two-channel CCD-camera for the 0.8 m Cassegrain telescope operated at the Wendelstein Observatory. To achieve a high efficiency this camera is equipped with two channels, operating in the wavelength range of 400 - 540 nm and 570 - 900 nm, respectively. Each channel is provided with a filter slider for three positions, an independent photometric shutter, and a 2k x 2k CCD (80% peak efficiency). The camera can simultaneously record a red and a blue image of its 10.7' x 10.7' field of view. In addition it has an offset guider and supports robotic operation: Active cooling provides the operating temperature of 160 K avoiding
the use of liquid nitrogen. Both CCDs share a single cryostat and can be aligned during operation. The complete vacuum control including pumping and cryopump cleaning can be operated remotely.