Publications

@misc{BettonvilHammerschlag_UniqueDesign2024,

title = {Unique design of the Dutch Open Telescope},

author = {F.C.M. Bettonvil; R.H. Hammerschlag; P. Sütterlin; G. Sliepen; A.P.L. Jägers, F. Snik; D.A. van Tricht},

url = {https://dutchopentelescope.nl/unique-design-dot/},

year  = {2024},

date = {2024-11-01},

urldate = {2024-11-01},

abstract = {The Dutch Open Telescope (DOT) is a telescope mainly used for high-resolution solar observations at the Observatorio Roque de los Muchachos (ORM) at a height of 2350m above sea level on the North-West Canary island La Palma, where the seeing can be excellent for high-resolution

observations of the sun. The DOT is of a special construction with open telescope on an also open tower to minimize the local thermal disturbance of the air above and in the telescope, where the primary beam is coming to the primary mirror. This is the basis of the advanced capabilities for large-field high-resolution images, sharp over the whole field during hours for movies showing the dynamic processes on the sun.},

keywords = {},

pubstate = {published},

tppubtype = {misc}

}

@misc{hammerschlag2023heliostat,

title = {Heliostat Anton Pannekoek Observatory (Heliostat APO)},

author = {Rob Hammerschlag},

url = {https://dutchopentelescope.nl/wp-content/uploads/2024/06/HeliostatAPO.pdf

https://api.uva.nl/stargazing/anton-pannekoek-observatory/anton-pannekoek-observatory.html},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

address = {Anton Pannekoek Institute (API), Amsterdam, The Netherlands},

institution = {Stichting Dutch Open Telescope (DOT)},

abstract = {The Heliostat is placed on the roof of the building where the astronomical Anton Pannekoek Institute (API) is housed. Two telescopes in two classical domes are placed from the beginning on the roof for night time observations. The Heliostat is added on the roof near the two domes. The solar light is reflected by the Heliostat to the inside of one of the domes through a window, which can be opened for this purpose. The light is reflected downward through a tube to a room underneath the dome. Instrumentation is installed in this Heliostat room for projection of the solar image and simultaneously the solar spectrum, which is shown under the solar image. Both are visible at the same time in real solar light. The following figures give an impression of the setup.},

keywords = {},

pubstate = {published},

tppubtype = {misc}

}

@misc{kommers2023lightweight,

title = {Light-weight towers with stable platform for astronomical, meteorological and civil-engineering measurements},

author = {Hans Kommers and Oscar Hartogensis and Rob Hammerschlag},

url = {https://www.nwo.nl/projecten/12399

https://dutchopentelescope.nl/wp-content/uploads/2024/06/LightWeightTowersGustyStorm.pdf},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

address = {Albert Cuyplaan 35, 3723 GK Bilthoven, The Netherlands},

institution = {Stichting Dutch Open Telescope (DOT)},

abstract = {Measurements were carried out on two towers at a distance of 900m on the test field of the KNMI (Royal Netherlands Meteorological Institute) near the village of Cabauw. The towers are open light-weight framework constructions, transparent to the air for minimum influence on the local meteorological situation of temperature, wind, and humidity. The developed special geometric design and construction keep the platform parallel to the ground under wind load, giving the open towers the required stability for measurements over large distances with directed optical beams. A Large Aperture Scintillometer (LAS) measures the scintillation between the tops of the two towers. It consists of two 15cm aperture telescopes, which are precisely pointed at each other. The Transmitter is placed on the first tower, and the Receiver on the second tower. Wind and acceleration sensors are installed on the tops of the towers in addition to the LAS. Continuous measurements are performed and data is stored on two computers. A heavy gusty storm occurred on June 5, 2019, and measurements showed that the scintillation signal remained undisturbed, proving that the telescopes remained precisely aligned. The horizontal motions in the heavy wind gusts are of the same size as during the shakes of a person on top of the tower. These experiences demonstrate the avoidance of tilt by the special geometry of the framework. The open light-weight towers are very suitable for the location of the Large Aperture Scintillometers (LAS), with measurements completely undisturbed even during heavy gusty storms with wind speeds up to 38 m/s (137 km/h). This construction is not only a demonstrator for meteorological measurements but also for astronomical applications.},

note = {Project 12399 TTW-NWO, Utrecht University, Wageningen University, Leiden University},

keywords = {},

pubstate = {published},

tppubtype = {misc}

}

@misc{kommers2023measurements,

title = {Open towers, uniquely stable, for measurements of the air above the landscape for climate improvement},

author = {Hans Kommers and Oscar Hartogensis and Sander Deelen and Rob Hammerschlag},

url = {https://dutchopentelescope.nl/wp-content/uploads/2024/06/LichtgewichtOpenTorensUniekStabielV.pdf},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

address = {Albert Cuyplaan 35, 3723 GK Bilthoven, The Netherlands},

institution = {Stichting Dutch Open Telescope (DOT)},

abstract = {A completely new type of towers has been developed to measure scintillation caused by air turbulence above the landscape. These measurements provide data on the exchange of heat and moisture between the atmosphere and the ground, which is important for climate research. The measurements are conducted using near-infrared and mm-wave beams with transmitters and receivers that must remain precisely aligned under all weather conditions. Extreme rigidity against tilting of the tower platform is required to ensure that the transmitters and receivers stay accurately aligned even in strong winds. The first prototypes of these unique open lattice towers have been designed and built, being lightweight yet having the required tilt stiffness. Two of these towers have been placed 900 meters apart in the meteorological test field of the KNMI in Cabauw. Measurements during an extreme storm showed that the scintillation signal remained undisturbed, confirming that the telescopes remained precisely aligned.},

note = {Project 12399 TTW-NWO, Utrecht University, Wageningen University, Leiden University},

keywords = {},

pubstate = {published},

tppubtype = {misc}

}