Optical-to-NIR Magnitude Measurements of the Starlink LEO Darksat Satellite and Effectiveness of the Darkening Treatment

J. Tregloan-Reed,A. Otarola,E. Unda-Sanzana, B. Haeussler, F. Gaete,J. P. Colque,C. Gonzalez-Fernandez,J. Anais,V Molina,R. Gonzalez,E. Ortiz,S. Mieske,S. Brillant, J. P. Anderson

Astronomy and Astrophysics（2021）

Univ Atacama | TMT Int Observ | Univ Antofagasta | European Southern Observ | Univ Cambridge

Cited 19|Views33

Abstract

Aims. We aim to measure the Sloan r′, Sloan i′, J, and Ks magnitudes of Starlink’s STARLINK-1130 (Darksat) and STARLINK-1113 low Earth orbit (LEO) communication satellites and determine the effectiveness of the Darksat darkening treatment from the optical to the near-infrared (NIR). Methods. Four observations of Starlink’s LEO communication satellites, Darksat and STARLINK-1113, were conducted on two nights with two telescopes. The Chakana 0.6 m telescope at the Ckoirama observatory (Chile) observed both satellites on 5 Mar. 2020 (UTC) and 7 Mar. 2020 (UTC) using a Sloan r′ and Sloan i′ filter, respectively. The ESO VISTA 4.1 m telescope with the VIRCAM instrument observed both satellites on 5 Mar. 2020 (UTC) and 7 Mar. 2020 (UTC) in the NIR J-band and Ks-band, respectively. Results. The calibration, image processing, and analysis of the Darksat images give r ≈ 5.6 mag, i ≈ 5.0 mag, J ≈ 4.2 mag, and Ks ≈ 4.0 mag when scaled to a range of 550 km (airmass = 1) and corrected for the solar incidence and observer phase angles. In comparison, the STARLINK-1113 images give r ≈ 4.9 mag, i ≈ 4.4 mag, J ≈ 3.8 mag, and Ks ≈ 3.6 mag when corrected for range, solar incidence, and observer phase angles. The data and results presented in this work show that the special darkening coating used by Starlink for Darksat has darkened the Sloan r′ magnitude by 50%, Sloan i′ magnitude by 42%, NIR J magnitude by 32%, and NIR Ks magnitude by 28%. Conclusions. The results show that both satellites increase in reflective brightness with increasing wavelength and that the effectiveness of the darkening treatment is reduced at longer wavelengths. This shows that the mitigation strategies being developed by Starlink and other LEO satellite operators need to take into account other wavelengths, not just the optical. This work highlights the continued importance of obtaining multi-wavelength observations of many different LEO satellites in order to characterise their reflective properties and to aid the community in developing impact simulations and developing mitigation tools.

Translated text

Key words

techniques: photometric,light pollution,methods: observational

Bibtex

AI Read Science

AI Summary

AI Summary is the key point extracted automatically understanding the full text of the paper, including the background, methods, results, conclusions, icons and other key content, so that you can get the outline of the paper at a glance.

Example

Background

Key content

Introduction

Methods

Results

Related work

Fund

Key content

Pretraining has recently greatly promoted the development of natural language processing (NLP)
We show that M6 outperforms the baselines in multimodal downstream tasks, and the large M6 with 10 parameters can reach a better performance
We propose a method called M6 that is able to process information of multiple modalities and perform both single-modal and cross-modal understanding and generation
The model is scaled to large model with 10 billion parameters with sophisticated deployment, and the 10 -parameter M6-large is the largest pretrained model in Chinese
Experimental results show that our proposed M6 outperforms the baseline in a number of downstream tasks concerning both single modality and multiple modalities We will continue the pretraining of extremely large models by increasing data to explore the limit of its performance

Try using models to generate summary,it takes about 60s

Must-Reading Tree

Example

Generate MRT to find the research sequence of this paper