Presentation + Paper
6 July 2018 Direct measurements of wind disturbances forces on the CTIO Blanco 4m telescope mount and its effect in tracking jitter
Author Affiliations +
Abstract
Since the CTIO 4m Blanco Telescope was successfully upgraded, commissioned, and integrated with the DECam Instrument in Sept 2012, the performance of the telescope mount tracking has been excellent, with a median tracking jitter of 0.025”, and 0.06”rms, for the declination, and right ascension axes respectively. Any occasional increase in mount tracking jitter, has been associated with wind induced torque disturbances, affecting both axes simultaneously, especially during high speed wind conditions, combined with dome, and wind direction alignment.

In order to investigate the response to the telescope mount servo control, to wind induced disturbances, we have instrumented the 4m Blanco Telescope mount, upper secondary ring, with a novel 2-axis direct wind force sensor, sampled at 200 Hz, using inexpensive pocket digital scale type load cells, this combined with a small surface area of 0.00375 m2, we have obtained wind pressure noise values of 0.4 Pa-rms.

Our investigation will compare the Power Spectral Density (PSD) of the wind disturbance forces, with the expected Kolgomorov model, and explore the correlation between wind disturbance forces, and mount tracking jitter.

Also we will establish under what dome, wind direction, and wind speed conditions the increased mount tracking jitter, could affect science image results, and cause an increase in image ellipticity, and FWHM. This information should help observers, in taking appropriate measures, to minimize the wind induced image degradation in the future.
Conference Presentation
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Michael Warner and Norman Diaz "Direct measurements of wind disturbances forces on the CTIO Blanco 4m telescope mount and its effect in tracking jitter", Proc. SPIE 10700, Ground-based and Airborne Telescopes VII, 107000J (6 July 2018); https://doi.org/10.1117/12.2311479
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KEYWORDS
Telescopes

Sensors

Data acquisition

Wind measurement

Error analysis

Image quality

Electronics

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