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Dark and Quiet - Starlight Constellations?

credit from Australia's Astronomer-at-large

(from the Astronomy in Australia Newsletter)

Starlink satellites as of 13 December 2021. (Credit Heavens Above)

Dark and quiet skies news Early in October, the United Nations Office for Outer Space Affairs (UNOOSA), the Government of Spain and the International Astronomical Union (IAU) held an online conference hosted by the Instituto de Astrofísica de Canarias (IAC) on Dark And Quiet Skies for Science and Society. It was the second international meeting on this topic, focusing on the implementation of recommendations from the first one a year earlier, with sessions devoted to artificial light at night, satellite constellations and radio astronomy. The conference attracted several hundred participants drawn mainly from the astronomical community, but with representation also from industry, government and regulatory bodies. All presentations are now available here. The sessions on satellite constellations and radio astronomy demonstrated that there has been considerable work since the first meeting on quantifying the effects of satellite constellations and evolving strategies to mitigate their effects, particularly in the optical/IR. For example, measurements were presented demonstrating that the Visorsats deployed by SpaceX in the Starlink constellation are typically 1.3 magnitudes fainter than the non-visored satellites in V (i.e. 30% as bright). This reduces their brightness below the threshold of the unaided eye, which addresses a major criticism of the Starlink constellations regarding their damaging effect on the cultural aspects of the night sky.

Starlink satellites as at 13 December 2021. (Credit Heavens Above)Other topics addressed in the conference focused on areas of interest to professional astronomers, including: national and international policies and laws;

the connection with the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) and its Science and Technology Subcommittee (STC);

algorithms being considered for avoidance and streak remediation in optical/IR observations; ‘SatHub’ - a proposed one-stop shop for observers worldwide to coordinate the observation and measurement of interference caused by satellite constellations (both optical and radio); the possibility of hosting an International Astronomical Union Centre for the protection of the dark and quiet sky from satellite constellation interference. In regard to COPUOS, the next meeting of the STC will be held in February 2022, and Australia will contribute through the Australian Space Agency. We in DISER’s International and Astronomy Branch will liaise with the Space Agency beforehand, informed by contributions from a number of sources, including visiting staff member Patrick Kennedy, who undertook a useful deep dive into the issue.

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