Daytime seeing variations in Paranal through a SHABAR system. Description of the method and first measurements from the PoET solar telescope
Abstract
Aims. In this paper we present the software and first seeing measurements from a SHAdow Band Ranger (SHABAR) system that is coupled with the recently comissioned PoET solar telescope, installed at ESO's VLT platform in the Paranal Observatory. The seeing measurements that are collected by this system play a pivotal role in the observational strategy of PoET, as it employs apertures ranging between 1 and 55 arcseconds to observe resolved solar regions. As such, the usage of the smaller apertures hinges upon good observational conditions, which are assessed through real-time measurements from the instrument. Methods. We employ a SHABAR system, consisting of a series of scintillometers that are non-uniformly spaced in a bar, measuring the scintillation of the incoming light. The scintillation is measured in individual detectors, which are then used to characterize the atmospheric turbulence at a given range of heights. We use previously derived formulations, following Kolmogorov turbulence models, to model the collected data and transform it into a seeing measurement. Results. We find that the Paranal daytime seeing can reach values close to 1 arcsecond in the early morning, before the ground temperature increases and creates turbulence in the lower layers of the atmosphere. Over the day, the seeing gradually worsens, with the median seeing reaching values larger than 4 arcseconds in the afternoon. We also find that these variations appears to be stable over the first weeks of observations, yielding compatible results when comparing 37 independent days of operations, with a median seeing of 2.37 arcseconds.
Related
- Can Historic Measurements cast light on the Spectral Differences found between the Pierre Auger Observatory and the Telescope Array?
- A Systematic Assessment of Total Stellar Mass Measurements with Spatially Resolved Photometry and Medium Bands at 1 < z < 9: The Impact of Mass-to-Light Variations and Outshining
- An autonomous approach to model daytime behavior of sub-ionospheric VLF signals over short and medium propagation paths in India
- CtaAgnVar : a Pipeline for Variability Studies with the Cherenkov Telescope Array Observatory
- High Frequency Wideband Study of FRB 20240114A with the Allen Telescope Array
BibTeX
@misc{silva2026daytime,
title = {{Daytime seeing variations in Paranal through a SHABAR system. Description of the method and first measurements from the PoET solar telescope}},
author = {A. M. Silva and B. Wehbe and A. Oliveira and M. Abreu and C. Cardenas-Conde and A. Cabral and P. Moreno and J. H. C. Martins and M. A. Monteiro and N. C. Santos and R. Gafeira},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.20479},
eprint = {2609.20479},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.20479},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Daytime seeing variations in Paranal through a SHABAR system. Description of the method and first measurements from the PoET solar telescope
AU - A. M. Silva
AU - B. Wehbe
AU - A. Oliveira
AU - M. Abreu
AU - C. Cardenas-Conde
AU - A. Cabral
AU - P. Moreno
AU - J. H. C. Martins
AU - M. A. Monteiro
AU - N. C. Santos
AU - R. Gafeira
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2609.20479
UR - https://arxiv.org/abs/2609.20479
AB - Aims. In this paper we present the software and first seeing measurements from a SHAdow Band Ranger (SHABAR) system that is coupled with the recently comissioned PoET solar telescope, installed at ESO's VLT platform in the Paranal Observatory. The seeing measurements that are collected by this system play a pivotal role in the observational strategy of PoET, as it employs apertures ranging between 1 and 55 arcseconds to observe resolved solar regions. As such, the usage of the smaller apertures hinges upon good observational conditions, which are assessed through real-time measurements from the instrument. Methods. We employ a SHABAR system, consisting of a series of scintillometers that are non-uniformly spaced in a bar, measuring the scintillation of the incoming light. The scintillation is measured in individual detectors, which are then used to characterize the atmospheric turbulence at a given range of heights. We use previously derived formulations, following Kolmogorov turbulence models, to model the collected data and transform it into a seeing measurement. Results. We find that the Paranal daytime seeing can reach values close to 1 arcsecond in the early morning, before the ground temperature increases and creates turbulence in the lower layers of the atmosphere. Over the day, the seeing gradually worsens, with the median seeing reaching values larger than 4 arcseconds in the afternoon. We also find that these variations appears to be stable over the first weeks of observations, yielding compatible results when comparing 37 independent days of operations, with a median seeing of 2.37 arcseconds.
ER -