Starlink and other satellite constellations: know them - avoid them
Luciano Nicastro (INAF OAS)
Tuesday 03/11/2020 @ 14:00, Sala IV piano Battiferro
Satellites mega-constellations are being deployed over our heads will have a relevant impact on optical/IR and radio astronomy. Statistical studies and observational data considering a total of about 26,000 satellites (but more than 100,000 are foreseen!) representing 18 constellations in development or deployment phase, among which the notorious Starlink, show that their impact will be relevant for telescopes with a large field of view and for telescopes with a medium-field that perform long exposures (100-1000 s). The extreme case is represented by the Vera C. Rubin Observatory where it is estimated that 30% of the observations performed during the first/last hours of the night (50% at twilight) would be "severely affected". Entities like ESO, IAU, AAS, RAS, NSF etc., are adopting initiatives and taking actions with the constellations operators (e.g. SpaceX) and national/international agencies that play a role in allowing satellites launches. Constellation operators must investigate practical solutions to mitigate the negative effects on astronomy, e.g. reducing significantly the reflectance of the satellites surface. The first batch of Starlink satellites launched, when illuminated by the Sun, showed a mean visual magnitude of 5.5. With the adoption of the new satellite design, called "VisorSat", things have improved, with an estimated mean magnitude of 7. It's a matter of fact that being able to predict which satellites will be in the field of view of an instrument at given date-time would be useful to decide if to observe or not. At least for observations that can be planned in advance. In this talk I'll briefly show the results of the above-mentioned study and will show a software tool that anyone can use to verify the presence of satellites in the field of view of a telescope at a given epoch from a given observing site. Having access to up-to-date satellite ephemeris is crucial in this respect.