arXiv subjects

Martin Timpe

Publications and source records attributed to Martin Timpe.

8 recordsLinked to original sources

arXiv2026

Optimizing Wavefront-Deformation Sensor Placement for Active Radio-Telescope Surfaces

Next-generation high-frequency radio telescopes require primary-surface accuracies that passive structures alone cannot reliably achieve. The Atacama Large Aperture Submillimeter Telescope (AtLAST), a 50 m single-dish concept operating up to $\approx$ 1 THz, imposes a $\approx$ 20 $\mu$m rms surface-accuracy requirement across its full aperture. This is practically unattainable for a purely passive reflector subject to gravitational, thermal, and wind-induced deformation. Closed-loop active collimation and surface control are therefore imperative, which in turn requires the deformation field to be known across the full aperture in real time. Measuring it directly at the necessary resolution across the complete surface is, however, hardly feasible; instead, the current AtLAST concept development foresees reconstructing the surface from a limited set of discrete sensor positions. An algorithmic framework is presented that optimizes the number and placement of these sensors to maximize the reconstructability of the deformation field. Finite-element analysis (FEA) load cases (gravity, thermal, wind) define the deformation space, from which a data-driven Proper Orthogonal Decomposition (POD) basis is derived; sensor positions are then chosen by a greedy optimization algorithm and then assessed via leave-one-out cross-validation. Applied to FEA deformations of AtLAST's Back-Up Structure (BUS), and assuming a sensor noise of 5 $\mu$m rms, the method reconstructs all load cases with 50 sensors to below 2.7 $\mu$m rms (worst case) residual (BUS-) surface error.

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arXiv2026

The Atacama Large Aperture Submillimeter Telescope (AtLAST): enabling large-scale sub-mm science beyond 2030

AtLAST is designed to be the largest (sub-)mm single-dish astronomical observatory and the first climate-neutral modern research infrastructure. It offers a unique combination of large aperture (50 m), large field of view (>1 deg), fast scanning speed (up to 3 deg/s), and high surface accuracy (20micron nighttime half wavefront error) that allows >=50% Ruze efficiency up to 1 THz. The design features a rocking chair mount with an active main reflector surface, a high precision closed-loop metrology system, and the space to house six major instruments. Instruments will be periodically updated as spectroscopic focal plane array, detector, coherent amplifier, and semiconductor technologies used in readout and backend electronics will advance over the next decades. AtLAST will be a multi-purpose facility that will produce transformational results in nearly all fields of Astrophysics, such as Astrochemistry, Galactic and Extragalactic Astronomy, Cosmology, Planetary science, Stellar and Solar Physics, High energy astrophysics, and Time domain astronomy. Its unrivalled throughput of 6170 m^2 deg^2 will enable wide-field unbiased surveys. These will overcome extragalactic confusion noise and enable the detection of normal galaxy populations out to z=7. AtLAST will reveal and characterise the missing baryons in the Universe, by mapping the elusive, low surface brightness gas within and around galaxies across cosmic time. AtLAST will be the first green off-grid observatory, powered by a bespoke renewable energy system and reusing its braking energy thanks to a cutting-edge energy recovery system. By sharing surplus power and technological know-how with local communities, AtLAST will contribute to energy justice in Chile. AtLAST's new bold vision of a sustainable pursuit of breakthrough astronomy is an exceptional opportunity to shape the future of scientific research infrastructures. [abridged]

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arXiv2026

Simulation-based dynamic pointing analysis of AtLAST under wind loading and fast-scan conditions

The Atacama Large Aperture Submillimeter Telescope (AtLAST) is a next-generation 50-m class single-dish facility concept designed for high-throughput, wide-field mapping at millimetre and submillimetre wavelengths. Its science goals require fast telescope motion while maintaining stringent dynamic pointing stability under realistic environmental and operational conditions. We present an end-to-end dynamic pointing analysis of the current AtLAST design, coupling a flexible structural model of the telescope mount with the intended cascaded main-axis control architecture, pointing-error evaluation, and measured site wind excitation. A key feature of the study is the use of high-rate wind measurements obtained at the AtLAST candidate sites before telescope construction. The measured wind time series are used as dynamic input to evaluate tracking under wind loading for multiple elevation angles, wind-speed classes, and wind angles of attack. The resulting wind-induced dynamic pointing error remains within the allocated tracking-stability budget for all budgeted wind conditions, confirming the adequacy of the current structural concept and main-axis control approach with respect to wind-driven pointing stability. Fast mapping is investigated separately using a Lissajous-daisy scan close to the kinematic limits of the mount. In contrast to the wind-loaded tracking case, the scan-induced response is more strongly linked to finite control bandwidth and trajectory-following accuracy, particularly in elevation. The analysis therefore identifies two distinct dynamic pointing regimes and provides guidance for future control optimization, feedforward strategies, and active compensation concepts.

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arXiv2024

A physical optics characterization of the beam shape and sidelobe levels for the Atacama Large Aperture Submillimeter Telescope (AtLAST)

(abridged) The Atacama Large Aperture Submillimeter Telescope (AtLAST) is undergoing a design study for a large (50 meter) single-dish submm-wavelength Ritchey-Chr\'etien telescope to be located 5050 meters above sea level in the Atacama Desert in northern Chile. It will allow for observations covering 30 to 950 GHz. Observing at such high frequencies with a 50~m primary mirror will be challenging, and has never been attempted thus far. This observational capability demands exquisite control of systematics to ensure a reliable beam shape, and to mitigate the expected sidelobe levels. Among them, critical issues that large telescopes like AtLAST need to deal with are introduced by the panel gap pattern, the secondary mirror supporting struts, mirror deformations produced by thermal and gravitational effects, and Ruze scattering due to surface roughness. Proprietary software such as TICRA-Tools allows for full-wave, complex-field physical optics simulations taking into account these features. Such calculations can be computationally expensive since the mirror surfaces are gridded (meshed) into a fine array in which each element is treated as a current source. If the telescope size is large and the wavelengths are short this may lead to very long running times. Here we present a set of physical optics results that allow us to estimate the performance of the telescope in terms of beam shape, directivity, sidelobes level and stray light. We also discuss how we addressed the computational challenges, and provide caveats on how to shorten the run times. Above all, we conclude that the scattering effects from the gaps and tertiary support structure are minimal, and subdominant to the Ruze scattering.

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arXiv2024

The Optical Design Concept for the Atacama Large Aperture Submillimeter Telescope (AtLAST)

The Atacama Large Aperture Submillimeter Telescope (AtLAST) aims to be the premier next generation large diameter (50-meter) single dish observatory capable of observations across the millimeter/sub-millimeter spectrum, from 30 to 950~GHz. The large primary mirror diameter, the 2-degree field of view and its large 4.7-meter focal surface give AtLAST a high throughput (aperture size times field of view) and grasp (throughput times spectral reach), with the ability to illuminate $>\mathcal{O}(10^7)$ detectors. The optical design concept for AtLAST consists of a numerically optimized two-mirror Ritchey-Chr\'etien system with an additional flat folding mirror, which enables a quick selection among its planned six instrument positions. We present the optical design concept and discuss the expected optical performance of AtLAST. We then present design concepts that can be implemented in the receiver and instrument optics to correct for astigmatism and mitigate the high degree of curvature of the focal surface in order to recover significant fractions of the geometric field of view at sub-millimeter wavelengths.

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arXiv2024

Technical requirements flow-down for the concept design of the novel 50-meter Atacama Large Aperture Submm Telescope (AtLAST)

The Atacama Large Aperture Submm Telescope (AtLAST) is a concept for a novel 50-meter class single-dish telescope operating at sub-millimeter and millimeter wavelengths (30-950 GHz). The telescope will provide an unprecedentedly wide field of view (FoV) of 1-2 degree diameter with a large receiver cabin housing six major instruments in Nasmyth and Cassegrain positions. The high observing frequencies, combined with the scanning operation movements with up to 3 deg/second, place high demands on the accuracy and stability of the optical and structural components. The design features the introduction of a rocking chair type mount with an iso-statically decoupled main reflector backup structure and an active main reflector surface with a high precision metrology system. The planned site location is in the Chilean Atacama Desert at approximately 5050 meters above sea level, near Llano de Chajnantor. This paper gives an overview of the optical, structural, and mechanical design concepts. It explains the flow-down from key science requirements to technical design decisions as well as showing design analogies from other existing large radio, (sub-)mm, and optical telescopes.

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arXiv2024

The conceptual design of the 50-meter Atacama Large Aperture Submillimeter Telescope (AtLAST)

The (sub)millimeter sky contains a vast wealth of information that is both complementary and inaccessible to other wavelengths. Over half the light we receive is observable at (sub)millimeter wavelengths, yet we have mapped only a small portion of the sky at sufficient spatial resolution and sensitivity to detect and resolve distant galaxies or star forming cores within their large-scale environments. For decades the astronomical community has highlighted the need for a large, high-throughput (sub-)mm ($\lambda\sim 0.35-10$ mm) single dish. The Atacama Large Aperture Submillimeter Telescope (AtLAST), with its 50-m aperture and $2^\circ$ maximal field of view, aims to be such a facility. We present here the preliminary design concept for AtLAST, developed through an EU Horizon 2020-funded design study. Our design approach begins with a long lineage of (sub)millimeter telescopes, relies on calculations and simulations to realize the optics, and uses finite element analysis to optimize the designs for the mechanical structure and subsystems. The demanding technical requirements for AtLAST, set by transformative science goals, have motivated the design effort to combine novel concepts with lessons learned from the past experience of previous efforts. The result is an innovative rocking chair design with six instrument bays, two of which are mounted on Nasmyth platforms, inside a large receiver cabin. Ultimately, AtLAST aims to achieve a surface accuracy of $\leq 20~\mu$m root mean square half wavefront error, corresponding a Ruze efficiency $>50\%$ at 950~GHz. We conclude that closed-loop metrology of the active primary surface will likely be required to achieve our surface accuracy goal. In the next phase of the project, we will prototype and test such metrology on existing platforms, with a goal of delivering a mature, construction-ready design by the end of this decade.

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arXiv2023

Progress in the Design of the Atacama Large Aperture Submillimeter Telescope

The Atacama Large Aperture Submillimeter Telescope (AtLAST) aims to be the premier next generation large diameter (50 meter) single dish observatory capable of observations across the millimeter/submillimeter spectrum, from 30~GHz to 1~THz. AtLAST will be sited in Chile at approximately 5100 meters above sea level, high in the Atacama Desert near Llano de Chajnantor. The novel rocking-chair telescope design allows for a unprecedentedly wide field of view (FoV) of 1-2$^\circ$ diameter, a large receiver cabin housing six major instruments, and high structural stability during fast scanning operations (up to $\sim 3^\circ$ per second in azimuth). Here we describe the current status of, and expected outcomes for, the antenna design study, which will be completed in 2024.

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