Using Hyper Suprime Camera data (a precursor of what is to come with Rubin Observatory) we assess trail masking mitigation strategies for satellite contamination. We examine HSC data of the Hubble COSMOS field where satellite trails have been identified by eye. Exercising the current LSST Science Pipelines on this data, we study the efficacy of masking satellite trails which appear in single visit exposures before they are assembled into a coadded frame. We find that the current routines largely mask satellite trails in single visits, but miss the extended low surface brightness features of the satellite trails. For a sufficiently wide mask, these faint features appear at a less significant level in the final coadd, as they are averaged down in a stack of tens of exposures. We study this print-through vs mask width. In this note, we describe some of the challenges we encountered in that effort, prospects for more complete removal of the low surface brightness tails of the masked trails, and possible science impacts.
This Report presents the main results of the Conference “Dark and Quiet Skies for Science and Society II” which took place on-line on 3–7 October 2021. This conference was the logical follow-up of the first one, organized as an on-line workshop with the same title on 5–9 October 2020. Both conferences were co-organized by UNOOSA, IAU and the Government of Spain and were well attended.The focus of the second conference was about the feasibility of implementing the recommendationspresented by the first one in its extensive report . The main qualifying difference between the first and the second conferences was a more explicit involvement of the industrial stakeholders and of space policy experts, whose contributions were instrumental in presenting a credible review of the proposed mitigating measures as well as of possible regulatory guidelines.As better explained in the report, the main findings of the conference are also being presented to the59th Session of the Scientific and Technical Sub Committee (STSC) of COPUOS in the form of a Working Paper.
Since 2019, SpaceX has been launching an increasing number of internet satellites into orbit around Earth. The satellite constellation, called Starlink, now includes nearly 1,800 members orbiting at altitudes of about 550 kilometers. Astronomers have expressed concerns that that these objects, which can appear as streaks in telescope images, could hamper their scientific observations.To quantify these effects, a team of researchers studied archival images captured by the National Science Foundation (NSF)-funded Zwicky Transient Facility (ZTF), an instrument that operates from Caltech's Palomar Observatory near San Diego. ZTF scans the entire night sky every two days, cataloguing cosmic objects that explode, blink, or otherwise change over time. This includes everything from supernovae to near-Earth asteroids. The Zwicky team members say they decided to specifically study the effects of Starlink satellites because they currently represent the largest low-Earth orbit, or LEO, constellation, and they have well-characterized orbits.The findings, reported in the January 17 issue of The Astrophysical Journal Letters, shows 5,301 satellite streaks appear in archival images taken between November 2019 and September 2021. The streaks are most apparent in so-called twilight observations, those taken at dawn or dusk, which are important for finding near-Earth asteroids that appear close to the sun in the sky. ZTF has discovered several asteroids of this nature, including 2020 AV2, the first asteroid spotted with an orbit that fits entirely within the orbit of Venus."In 2019, 0.5 percent of twilight images were affected, and now almost 20 percent are affected," says Przemek Mróz, study lead author and a former Caltech postdoctoral scholar who is now at the University of Warsaw in Poland.In the future, the scientists expect that nearly all of the ZTF images taken during twilight will contain at least one streak, especially after the Starlink constellation reaches 10,000 satellites, a goal SpaceX hopes to reach by 2027."We don't expect Starlink satellites to affect non-twilight images, but if the satellite constellation of other companies goes into higher orbits, this could cause problems for non-twilight observations," Mróz says.Yet despite the increase in image streaks, the new report notes that ZTF science operations have not been strongly affected. Study co-author Tom Prince, the Ira S. Bowen Professor of Physics, Emeritus, at Caltech, says the paper shows a single streak affects less than one-tenth of a percent of the pixels in a ZTF image."There is a small chance that we would miss an asteroid or another event hidden behind a satellite streak, but compared to the impact of weather, such as a cloudy sky, these are rather small effects for ZTF."Prince says that software can be developed to help mitigate potential problems; for example, software could predict the locations of the Starlink satellites and thus help astronomers avoid scheduling an observation when one might be in the field of view. Software can also assess whether a passing satellite may have affected an astronomical observation, which would allow astronomers to mask or otherwise reduce the negative effects of the streaks.The new study also looked at the effectiveness of visors on the Starlink satellites, which SpaceX added beginning in 2020 to block sunlight from reaching the spacecraft. According to the ZTF observations, the visors reduce the satellite brightness by a factor of about five. That dims the satellites down to an apparent brightness level of 6.8 magnitude (the brightest stars are first magnitude, and the faintest stars we can see with our eyes are about sixth magnitude).This is still not dim enough to meet standards outlined by the Satellite Constellations 1 (SATCON1) workshop in 2020, a gathering sponsored by the NOIRLab (National Optical-Infrared Astronomy Research Laboratory) and the AAS (American Astronomical Society) to bring together astronomers, policymakers, and other experts to discuss the impact of large satellite constellations on astronomy and society. The group called for all LEO satellites to be at seventh magnitude or fainter.The study authors also note their study is specific to ZTF. Like ZTF, the upcoming Vera C. Rubin Observatory, under construction in Chile, will also survey the sky nightly, but due to its more sensitive imager, astronomers predict that it may be more negatively affected by satellite streaks than ZTF.Other authors of the study, titled, "Impact of the SpaceX Starlink Satellites on the Zwicky Transient Facility Survey Observations," include Richard Dekany (BS '89), Matthew Graham, Steven Groom, and Frank Masci of Caltech; Dmitry Duev, a former Caltech postdoc now at Weights & Biases Inc.; Angel Otarola of the European Southern Observatory; and Michael S. Medford of UC Berkeley and Lawrence Berkeley National LaboratoryZTF is funded by NSF and an international collaboration of partners. Additional support comes from the Heising-Simons Foundation and Caltech. ZTF data are processed and archived by Caltech's IPAC astronomy center. NASA supports ZTF's search for near-Earth objects through the Near-Earth Object Observations program.
[Tony Beasley, director of the National Radio Astronomy Observatory]: “We live in a special time where society can give us money to do pure research and learn about the universe. But if we’re being perfectly honest, we’re also given this responsibility to develop cool stuff that eventually ends up in your cellphone, and educate people and march forward. We get paid to pose and solve difficult problems, and these constellations are just problems that need to be fixed.“The thing I find a little frustrating is, it’s easy when you’ve got amazing internet access to try placing limits on these companies and decide the future of all this. But there’s, what, three-quarters of the world who struggle to get access to this resource. Providing them with this is, I think, at least as important as a dark night sky, in some sense. So we’ve got to balance. And that’s the thing that I have to say I sometimes find missing in the discussion.“Right now, we’re in a ‘Holy shit, what can we possibly do’ mode. But as I feel we have done, the optical community just needs to start solving problems and working more with the companies, and we’ll get around it.”
Oleg Kutkov is a Ukrainian engineer and amateur astronomer who bought a Starlink terminal on Ebay in December to take apart for fun, never thinking he’d actually be able to use it in his apartment in Kiev. But when Russia invaded in February, Elon Musk activated Starlink service over Ukraine, and Kutkov has been using it as his backup internet service ever since.<snip>Kutkov said he used to side with astronomers like Lawler in thinking that the concerns about Starlink impeding observations of the cosmos outweighed its benefits, but Russia’s invasion is changing his mind.“I was 100% with astronomers,” Kutkov said. “But in the current situation, when we really need internet connectivity, that’s starting to be more important.”
https://www.cnn.com/2022/04/04/world/satellite-pollution-night-sky-view-scn/index.htmlNothing new here except the usual anti-Starlink talking points, but at least there's a small attempt to present the other side:QuoteOleg Kutkov is a Ukrainian engineer and amateur astronomer who bought a Starlink terminal on Ebay in December to take apart for fun, never thinking he’d actually be able to use it in his apartment in Kiev. But when Russia invaded in February, Elon Musk activated Starlink service over Ukraine, and Kutkov has been using it as his backup internet service ever since.<snip>Kutkov said he used to side with astronomers like Lawler in thinking that the concerns about Starlink impeding observations of the cosmos outweighed its benefits, but Russia’s invasion is changing his mind.“I was 100% with astronomers,” Kutkov said. “But in the current situation, when we really need internet connectivity, that’s starting to be more important.”
Sad perspective as Europe has also fallen prey to the hard cash with the Kuiper deal. My critiques, should this project go forward as advertised, are unchanged -or even heightened considering the slight orbital altitude increase- from those discussed for Starlink's case.https://mobile.twitter.com/Spicey_Spiney/status/1510951865927753738
Quote from: su27k on 04/06/2022 02:49 amhttps://www.cnn.com/2022/04/04/world/satellite-pollution-night-sky-view-scn/index.htmlNothing new here except the usual anti-Starlink talking points, but at least there's a small attempt to present the other side:QuoteOleg Kutkov is a Ukrainian engineer and amateur astronomer who bought a Starlink terminal on Ebay in December to take apart for fun, never thinking he’d actually be able to use it in his apartment in Kiev. But when Russia invaded in February, Elon Musk activated Starlink service over Ukraine, and Kutkov has been using it as his backup internet service ever since.<snip>Kutkov said he used to side with astronomers like Lawler in thinking that the concerns about Starlink impeding observations of the cosmos outweighed its benefits, but Russia’s invasion is changing his mind.“I was 100% with astronomers,” Kutkov said. “But in the current situation, when we really need internet connectivity, that’s starting to be more important.”Sure, under bombing in a war you might be all for an airstrike to level a beautiful forest and its inhabitants when an enemy tank batallion is entrenched there, rather than the usual attitude of wanting to preserve it as much as practicable. Uses for extraordinary circumstances should not justify everything.
Leveling a forest? Talk about hyperbole!We’re literally just talking about being able to see satellites in space for a short time after sunset and before sunrise.
So how long was the exposure? Most of the clutter here appears to be aircraft. How many of the satellite trails are starlink? This is simply meaningless.Street lighting is a far more serious desecration of the night sky for most of the human race. I live well out in the country and I can only see a few dozen stars.
... but the deployed constellation is essentially invisible to 95% of people...
Quote from: Robotbeat on 04/06/2022 02:15 pm... but the deployed constellation is essentially invisible to 95% of people...That's because our skies are so polluted. Using this argument is like saying it's fine to throw plastic into the ocean because there's already a lot of plastic in the ocean so it doesn't matter, and it helps the less fortunate get rid of their trash.
Quote from: eeergo on 04/06/2022 10:20 amQuote from: su27k on 04/06/2022 02:49 amhttps://www.cnn.com/2022/04/04/world/satellite-pollution-night-sky-view-scn/index.htmlNothing new here except the usual anti-Starlink talking points, but at least there's a small attempt to present the other side:QuoteOleg Kutkov is a Ukrainian engineer and amateur astronomer who bought a Starlink terminal on Ebay in December to take apart for fun, never thinking he’d actually be able to use it in his apartment in Kiev. But when Russia invaded in February, Elon Musk activated Starlink service over Ukraine, and Kutkov has been using it as his backup internet service ever since.<snip>Kutkov said he used to side with astronomers like Lawler in thinking that the concerns about Starlink impeding observations of the cosmos outweighed its benefits, but Russia’s invasion is changing his mind.“I was 100% with astronomers,” Kutkov said. “But in the current situation, when we really need internet connectivity, that’s starting to be more important.”Sure, under bombing in a war you might be all for an airstrike to level a beautiful forest and its inhabitants when an enemy tank batallion is entrenched there, rather than the usual attitude of wanting to preserve it as much as practicable. Uses for extraordinary circumstances should not justify everything.Megaconstellation is not just for extraordinary circumstances, I don't know why this even needs to be pointed out, there're already hundreds of thousands of users, most of them are not in a war zone. This particular case does not prove that constellation is only useful during a war, it just took a war for someone to realize that an internet connection is a privilege which not everybody on Earth has, and constellation can help these people.And the main point of the article is pitching aesthetics of the sky - an entirely subjective thing - against people's need for internet connection, a stupid comparison to begin with. By this same logic we can also forbid wind farms or solar farms because they're an eyesore.
Quote from: Lee Jay on 04/06/2022 02:23 pmQuote from: Robotbeat on 04/06/2022 02:15 pm... but the deployed constellation is essentially invisible to 95% of people...That's because our skies are so polluted. Using this argument is like saying it's fine to throw plastic into the ocean because there's already a lot of plastic in the ocean so it doesn't matter, and it helps the less fortunate get rid of their trash.No,
it’s like saying flying a silent electric airplane is fine because the visual impact is really not a problem (oh look, I can see an airplane! Oh, the humanity!). That’s literally what we’re talking about here.
But you have to massively exaggerate the issue using hyperbolic analogies for anyone to care.
