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1. The Impact of Satellite Constellations on Solar System Science With LSST

   https://doi.org/10.5194/epsc-dps2025-856  

   Eggl, Siegfried; Cornwall, Samuel; Dadighat, Michelle; Jangid, Nayan; Peel, Michael; Rawls, Meredith L; Skinner, Mark A; Tyson, J Anthony; Walker, Constance E (July 2025, Europlanet / American Astronomical Society)

   Ground-based astronomical surveys such as the much anticipated Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) [1] face new challenges due to the increasing number of satellites in Low and Medium Earth Orbit (LEO & MEO). With hundreds of thousands of artificial satellites likely to be launched in the near future as estimated by the IAU CPS, satellite trails in astronomical images will become frequent enough to require some form of mitigation. Limiting the maximum brightness of artificial satellites to below 7th magnitude is one of the proposed means to reduce satellite impact on Rubin data, which prevents the most severe systematic errors and widespread data loss in LSST camera sensors [2]. Glints caused by satellites and space debris are also expected to pollute LSST alerts [3].Brighter objects may require active satellite-avoidance scheduling schemes such as investigated by Hu et al. [4]. The IAU Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU CPS) in cooperation with the Aerospace Corp. is currently developing online services with global API access, such as SatChecker that enable satellite-avoidance [5,6].  However, dodging satellites would effectively decrease observing time in large sky surveys such as the LSST. In this contribution we report updates on satellite brightness mitigation efforts including technologies developed by both satellite constellation operators to darken their constellations as well as new IAU CPS tools for astronomers intended to help tackle this challenge. We also discuss the potential satellite constellation related losses in Solar System Object (SSO) discovery based on recent Sorcha simulations [7].Acknowledgments: The authors acknowledge support from the National Science Foundation through the award Collaborative Research: SWIFT-SAT: Minimizing Science Impact on LSST and Observatories Worldwide through Accurate Predictions of Satellite Position and Optical Brightness NSF Award Numbers 2332736 and 2332735. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.References:  [1] Ivezić, Ž., et al. (2019) “LSST: From science drivers to reference design and anticipated data products.” The Astrophysical Journal 873.2 : 111. [2] Tyson, J.A. et al. (2020) “Mitigation of LEO satellite brightness and trail effects on the Rubin Observatory LSST,” The Astronomical Journal, 160(5), p. 226. [3] Tyson, J.A., Snyder, A., Polin D., Rawls, M.L. and Ivezić Ž. (2024) Expected Impact of Glints from Space Debris in the LSST. The Astrophysical Journal Letters 966, no. 2 : L38. [4] Hu, J.A. et al. (2022) “Satellite constellation avoidance with the Rubin Observatory Legacy Survey of Space and Time,” The Astrophysical Journal Letters, 941(1). [5] IAU CPS SatChecker (https://satchecker.readthedocs.io/en/latest/fov.html), accessed 2025 May 2. [6] Skinner, M. A., Coursey, C.D., and George, E.R. (2023). Dark and Quiet Skies: A predictive technique to mitigate the impact of satellite reflections on astronomical observatories. 74th International Astronautical Congress (IAC), Baku, Azerbaijan, 2-6 October 2023. [7] Schwamb, M. et al. “Sorcha: A Solar System Survey Simulator for the Legacy Survey of Space and Time”, The Planetary Science Journal (in press). 

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2. UNDERSTANDING THE IMPACT OF SATELLITES ON RADIO ASTRONOMY OBSERVATIONS

   Peel, M; Eggl, S; Rawls, ML; Qui, H; Clements, DL (May 2025, European Space Agency Space Debris Office)

   Lemmens, S; Flohrer, T; Schmitz, F (Ed.)

   Radio telescopes observe extremely faint emission from astronomical objects, ranging from compact sources to large scale structures that can be seen across the whole sky. Satellites actively transmit at radio frequencies (particularly at 10±20 GHz, but usage of increasing broader frequency ranges are already planned for the future by satellite operators), and can appear as bright as the Sun in radio astronomy observations. Remote locations have historically enabled telescopes to avoid most interference, however this is no longer the case with dramatically increasing numbers of satellites that transmit everywhere on Earth. Even more remote locations such as the far side of the Moon may provide new radio astronomy observation opportunities, but only if they are protected from satellite transmissions. Improving our understanding of satellite transmissions on radio telescopes across the whole spectrum and beyond is urgently needed to overcome this new observational challenge, as part of ensuring the future access to dark and quiet skies. In this contribution we summarise the current status of observations of active satellites at radio frequencies, the implications for future astronomical observations, and the longer-term consequences of an increasing number of active satellites. This will include frequencies where satellites actively transmit, where they unintentionally also transmit, and considerations about thermal emission and other unintended emissions. This work is ongoing through the IAU CPS. 

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3. Report on LEO satellite impacts on ground-based optical astronomy for the Rubin Observatory LSST

   Kandula, P; Kelvin, L; Nourbakhsh, E; Polin, D; Prince, T; Rawls, M; Snyder, A; Smart, B; Stubbs, C; Tyson, A; et al (January 2026, arXiv)

   In August 2025 a workshop was convened to bring together experts to better understand steps that can be taken to mitigate the impact of satellite constellations on astronomical observations. At the time, just over 12,000 operational satellites were in low-Earth orbit (LEO). Although reflected sunlight and emissions all across the electromagnetic spectrum from artificial satellites impact scientific observations and the sky, the workshop focused on reflected sunlight in the wavelength range 330 nm to 1100 nm. This aligns with the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) planned imaging observations over the coming decade. Among other conclusions, we affirm previous recommendations that tracked satellite apparent magnitudes should be no brighter than 7th AB mag. The workshop participants discussed over 30 publications, reports, and presentations, and arrived at the Findings and Recommendations presented here. During the workshop, in addition to affirming many existing recommendations and best practices, the group discovered new issues and devised possible mitigations. These were nearly equally divided between advice to satellite builders and operators and to the observational astronomy community. While the workshop prioritized considerations for LSST, our hope is that many of the Findings and Recommendations will also apply to other observatories and constellations, and that all satellite companies will continue to engage in dialog with sky observers across the globe. 

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4. A Newly Documented Whole‑Sky Circumpolar Constellation in Alaskan Gwich’in

   Cannon, Chris; Holton, Gary (January 2014, Arctic anthropology)

   Traditional approaches to the documentation of indigenous astronomical knowledge often assume a one-to-one or near one-to-one correspondence between indigenous and classical constellation terms. Only a single constellation, equated with the Big Dipper, is robustly attested across the Northern Dene languages. Here we provide evidence from Gwich’in (Dene) that shows that the equation of this single Gwich’in constellation with the classical constellation is only partial. The Gwich’in constellation yahdii is actually a whole-sky constellation that maps nearly the entire sky. The Big Dipper is the tail of yahdii, and the remaining stars in the constellation are identified by other Gwich’in body-part terms, forming a unified functional conceptualization of the sky. Our work demonstrates how observational and cultural biases can prejudice the description of cultural astronomy. Dene astronomy is much richer than has been previously claimed and provides the first well-documented indigenous example of a whole-sky constellation. 

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5. Simulated Impact on LSST Data of Starlink V1.5 and V2 Satellites

   https://doi.org/10.3847/1538-3881/ae196c  

   Kandula, Phanindra; Tyson, J Anthony; Askari, Jacob; Fankhauser, Forrest (December 2025, The Astronomical Journal)

   Abstract The new Starlink V2 satellites incorporate improvements to the chassis brightness through dielectric mirrors, off-pointing solar arrays, and blackened exposed components. For the general case in which the reflectivities are initially unknown, we simulate Legacy Survey of Space and Time (LSST) operations and repeated photometry of every satellite in simulated model constellations. We derive a brightness model of the Starlink V2 satellite and study the simulated apparent brightness as a function of the satellite position relative to the observer and the Sun. Simulated V2 Starlink satellites appear brightest at two distinct positions in the sky: toward the Sun at low elevations where light is specularly reflected, and nearly overhead where the satellite is closest to the observer. A simulation of Starlink V2 satellites at 550 km height distributed across a series of Walker constellations with varying inclinations was analyzed to study the impact on LSST observations. For every thousand V2 Starlink satellites observed, we find only 0.93 will appear brighter than 7th magnitude. The off-pointed solar array and reduced diffuse reflection of the chassis mitigate the brightness. Finally, we simulate lowering this Walker constellation to 350 km. Only 0.56 V2 Starlink satellites per thousand brighter than 7 AB magnitude will be observed in the first hour at this height. This is a 40% reduction in number of bright satellites entering the focal plane compared to the constellation at 550 km height. We find that a combination of factors yield an apparent surface brightness of these satellites for LSST operations only 5% brighter than at 550 km orbit. 

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