Architecture of the metrology for the SRT

Pisanu, T.; Buffa, Franco; Deiana, Gian Luigi; Marongiu, P.; Morsiani, M.; Pernechele, Claudio; Poppi, S.; Serra, G.; Vargiu, G. P.

doi:10.1117/12.925547

Cited by 8 publications

(7 citation statements)

References 2 publications

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“…Moreover, several solutions are being studied and implemented so as to perform real-time measurements of the re°ector deformations and the misalignments errors in the subre°ector position, with the ¯nal aim of correcting them in a \closed-loop" strategy (Pisanu et al, 2012;Prestage et al, 2004):…”

Section: Optical System and Active Surfacementioning

confidence: 99%

Sardinia Radio Telescope: General Description, Technical Commissioning and First Light

Bolli

Orlati

Stringhetti

et al. 2015

J. Astron. Instrum.

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the Sardinia Radio Telescope (SRT) went through the technical commissioning phase. The characterization involved three¯rst-light receivers, ranging in frequency between 300 MHz and 26 GHz, connected to a Total Power back-end. It also tested and employed the telescope active surface installed in the main re°ector of the antenna. The instrument status and performance proved to be in good agreement with the expectations in terms of surface panels alignment (at present 300 m rms to be improved with microwave holography), gain ($0.6 K/Jy in the given frequency range), pointing accuracy (5 arcsec at 22 GHz) and overall single-dish operational capabilities. Unresolved issues include the commissioning of the receiver centered at 350 MHz, which was compromised by several radio frequency interferences, and a lower-than-expected aperture e±ciency for the 22-GHz receiver when pointing at low elevations. Nevertheless, the SRT, at present completing its Astronomical Validation phase, is positively approaching its opening to the scienti¯c community.

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Section: Optical System and Active Surfacementioning

confidence: 99%

Sardinia Radio Telescope: General Description, Technical Commissioning and First Light

Bolli

Orlati

Stringhetti

et al. 2015

J. Astron. Instrum.

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“…As an important part of the radio telescope control system (Kathleen et al 2018), an accurate pointing model is capable of reducing pointing errors that decrease the snapshot imaging quality and stability (Bhatnagar & Cornwell 2017). Larger wind load and larger temperature difference at the new site with higher altitude (5050 m) will lead to the deformation of the primary reflector of the telescope and ultimately affect its pointing accuracy (Gawronski 2007;Pisanu et al 2014;Fu et al 2016). Although the existing pointing model of the CSO telescope is doing well on the observation conditions at Maunakea, Hawaii, it will be difficult for the telescope to maintain the same performance at the new site due to a very different environment (e.g., the altitude rises from 4070 to 5050 m, the average wind speed is 10 m s −1 in winter, and the average temperature difference between day and night reaches 10°C (ALMA 2010)).…”

Section: Introductionmentioning

confidence: 99%

“…Operation and observation of these telescopes show that these additional terms may be very helpful in reducing the optical pointing errors. In addition, some engineers also take advantage of directly measuring the tilt of the elevation axis of the telescope (e.g., the GBT) with inclinometers to correct the optical pointing errors (Prestage et al 2009;Pisanu et al 2014;Fu et al 2016Fu et al , 2019White et al 2022).…”

Section: Introductionmentioning

confidence: 99%

An Improved Radio Pointing Model for SHARC II of the Caltech Submillimeter Observatory Telescope

Chen¹,

Wang²,

Zhou³

2022

PASP

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In this research, we develop a new method of upgrading the radio pointing model of an important instrument of the Caltech Submillimeter Observatory (CSO) telescope, i.e., the Submillimeter High Angular Resolution Camera II (SHARC II), by making three types of structural reconstruction of its existing model. First, the axial displacement of the secondary reflector of the telescope is introduced to the radio pointing model for SHARC II. Second, the multi-layer perceptron is applied for better describing higher-order terms in the radio pointing model, which are hard to be mathematically formulated. Third, a receding horizon modeling method is proposed to replace the time-dependent term in the existing model, for better reducing the negative impact of the time drift on the model’s accuracy. Results of numerical experiments and statistical significance analysis based on the real pointing data of SHARC II show that the reconstructed radio pointing model can improve the accuracy of estimating the pointing error, and the proposed method of upgrading the radio pointing model is effective. Considering that the CSO telescope will be moved from the old site at Maunakea, Hawaii to the new site at the Chajnantor Plateau in Chile, the proposed methods of upgrading the radio pointing model are expected to be employed for pointing correction after the telescope is refurbished at the new site.

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“…2 This goal is met also by means of a metrology system. 3 If no active control of the surface 4 is performed, the radio telescope structure allows operations up to about 20 GHz, with an acceptable loss of efficiency. This paper describes the SRT minor servo system.…”

Section: Introductionmentioning

confidence: 99%

Diving into the Sardinia Radio Telescope minor servo system

et al. 2012

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The Sardinia Radio Telescope (SRT) is a new 64-metre, Gregorian-shaped antenna built in Sardinia (Italy). It\ud is designed to carry out observations up to 100 GHz.\ud The telescope is provided with six focal positions: primary, Gregorian and four beam-waveguide foci. This\ud paper describes the project of the servo system which allows the focus and receiver selection during the instrument\ud setup. This system also operates, at the observation stage, the compensation of some of the stucture deformations\ud due to gravity, temperature variations and other environmental effects.\ud We illustrate the system features following a bottom-up approach, analysing all the project layers ranging\ud from low-level systems, as the hardware controls, to the design and implementation of high-level software, which\ud is based on the distributed objects ACS (ALMA Common Software) framework.\ud Particular focus will be put on the links among the hierarchical levels of the system, and on the solutions\ud adopted in order to guarantee that the control of the servo system is abstracted from the underlying hardware

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Architecture of the metrology for the SRT

Cited by 8 publications

References 2 publications

Sardinia Radio Telescope: General Description, Technical Commissioning and First Light

Sardinia Radio Telescope: General Description, Technical Commissioning and First Light

An Improved Radio Pointing Model for SHARC II of the Caltech Submillimeter Observatory Telescope

Diving into the Sardinia Radio Telescope minor servo system

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