Appeal by Astronomers

Safeguarding the Astronomical Sky (IT)

paper_I_arXivpaper_II_(arXiv) -> the FULL paper <- press EN_PDFpress IT_PDF




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This is an international appeal by professional astronomers open for subscription to ask for an intervention from institutions and governments.

Astronomical observations from the ground can be greatly harmed by the ongoing deployment of large satellite fleets in preparation for the next generation of telecommunications.

For centuries the astronomical observations from the ground have led to exceptional progress in our scientific understanding of the Laws of Nature. Currently, the capability of astronomical instrumentation from the ground is endangered by the deployment of satellites fleets.

Through this international appeal and following the same concerns expressed by the International Astronomical Union, IAU [1] and other institutions, we raise a formal request for greater effective protection and safeguard for professional astronomical observations from the ground, guaranteeing the right to observe a sky free from unnecessary artificial polluting sources.

In particular, all the signers, astronomers and collaborators wish to manifest humanly and personally their worry and contrariety to the sky coverage produced by artificial satellites, which represent a dramatic degradation of the scientific content for a huge set of astronomical observations.

The sky degradation is not only due to light pollution in the sky near cities and the most populated areas, but it is also due to artificial satellite fleets crossing and scarring observations with bright parallel streaks/trails at all latitudes.

Astronomers are extremely concerned by the possibility that Earth may be blanketed by tens of thousands of satellites, which will greatly outnumber the approximately 9,000 stars that are visible to the unaided human eye. This is not some distant threat. It’s already happening. The american private company SpaceX has already put 180 of these small satellites, collectively called Starlink, in the sky and plans to constellate the whole sky with about 42,000 satellites (placed at three different quota: 340km, 550km and 1150km). Thus, together with other telecommunication space projects in the near future (i.e. the English OneWeb, the Canadian Telesat, the American Amazon, Lynk and Facebook, the Russian Roscosmos and the Chinese Aerospace Science and Industry corp), there could be over 50,000 small satellites encircling the Earth (at different altitudes) for various telecommunication purposes but mainly delivering internet.

These new satellites are small, mass-produced, and orbit very close to the Earth with the intent to provide speedy internet connection with low-latency signals. But that closeness (~340Km) also makes them more visible, and brighter in the night sky especially when lighted by the Sun (satellites launched by SpaceX, 180 at the present day, are brighter than 99 percent of the population of objects visible by the Earth orbit ).

The current total number of cataloged objects in Earth orbit is less than 20,000 among spacecrafts, rocket bodies, fragmented mission and other related debrids, so with only the nominal Starlink fleet the total number of orbiting objects will triple (see pictures).(*)

In the mid and long term, this will severely diminish our view of the Universe, create more space debris, and, deprive humanity of an unblemished view of the night sky. It has been computed that most of these satellites will be visible to the naked eye (with a brightness between the 3rd and 7th magnitude particularly in the time after sunset and before sunrise, reaching the brightness of the stars in the Ursa Minor constellation (e.g. there are only 172 stars in the whole sky exceeding the expected brightness of Starlink satellites). Thus with 50k satellites the “normality” will be a sky crowded with artificial objects (every one square degree of the sky will have a satellite crawling in it along the whole observing night).

Not only observations with wide-field survey telescopes will be damaged (e.g. LSST [2] capable to scan and perform a survey of the entire sky in three nights or VST [3] with its 268MegaPixels camera and a FOV of 1 square degree or Pan-STARRS [4] with its FOV of 7 square degrees and 1.4 Giga pixels camera, …), but also deep/long exposures with small-field facilities will be unavoidably impaired, see picture and [7].

Considering that large area astronomical observations and sky survey are commonly used in NEO and asteroids monitoring and research related projects to guard the Earth planet from potential impact events, such satellite constellations could negatively impact on the ability to prevent and warn the whole humankind.(*)

Few starlink satellites visible in a mosaic of an astronomical image (NSF’s National Optical-Infrared Astronomy Research Laboratory/NSF/AURA/CTIO/DELVE)

This light pollution is extremely damaging for astronomical observations at all wavelengths. The recent attempt to use non-reflecting paint on the body (i.e. not the solar panels which represents 75% of the reflecting surface) of one of the Starlink satellite (n.1130 DARKSAT), see [8], even if their brightness would reduce to zero (which is impossible since the solar panels, which represent 3/4 of the reflective surface, would remain uncovered), the degradation for scientific observations will remain high for two reasons: 1) the stars and other objects in the universe will be eclipsed, therefore harming time-dependent (variability) studies, and,  2) the reflectivity of surface depends on the observational wavelength, so what becomes dark in one part of the spectrum (e.g. visible) remains bright or shines in other parts of the spectrum  (e.g. infrared or radio).(**)

It should also be noted that during nominal service operations SpaceX expects to dismiss and replace from 2,000 to 8,000 Starlink satellites every year, disintegrating them in the lower atmosphere, with all related issues.(*)

What is not widely acknowledged is that the development of the latest generation telecommunication networks (both from space and from Earth) already has a profound impact on radio-astronomical observations (at all sub-bands): with LEO satellite fleets it is feared that the situation will become unbearable.

In particular, low Earth orbit satellite’s spectral windows identified to communicate with earth stations in the Ku (12-18GHz), Ka (27-40GHz) and V (40-75GHz) bands will overlap with the nominal radio-astronomy bands and so will interfere with ground radio telescopes and radio interferometers, making the radio detectors enter in a non-linear regime in the K band (18.26.5GHz) and in Q band (33-50GHz). This fact will irreparably compromise the whole chain of analysis in those bands with repercussions on our understanding of the Universe, or even, making the astrophysics community blind to these spectral windows.

To aggravate the matter, with the current technological development, the planned density of radio frequency transmitters is impossible to envisage. In addition to millions of new commercial wireless hot spot base stations on Earth directly connected to the ~50,000 new satellites in space, will produce at least 200 billion of new transmitting objects, according to estimates, as part of the Internet of Things (IoT) by 2020-2022, and one trillion of objects a few years later. Such a large number of radio-emitting objects could make radio astronomy from ground stations impossible without a real protection made by countries’ safe zones where radio astronomy facility are placed. We wish to avoid that technological development without serious control would turn radio astronomy practice into an ancient extinct science.


We, astronomers subscribing to this appeal state THERE IS NO MORE TIME TO DISCUSS, IT IS TIME TO ACT!


  1. to be committed to provide legal protection to ground astronomical facilities in all of the available observation electromagnetic windows.
  2. to put on hold further Starlink launches (and other projects) and carry out an accurate moratorium on all technologies that can negatively impact astronomical observations from space and from the ground, or impact on the scientific, technological and economic investments that each State engages in astrophysical projects.
  3. to put in place a clear evaluation of risks and predictive impacts on astronomical observatories (i.e. loss of scientific and economic value), giving stringent guidelines to private individuals, societies and industries to plan satellite investments without clearly understanding all of the negative effects on outstanding astronomical facilities.
  4. that the US Federal Communications Commission (FCC) and any other national agency be wary of granting permission to ship non-geostationary low-orbit  satellites into orbit or alternatively to limit the authorization of only satellites  being above the airspace of the “home country”.
  5. to demand a worldwide orchestration, where national and international astronomical agencies can impose the right of veto on all those projects that negatively interfere with astronomical outstanding facilities.
  6. to limit and regulate the number of telecommunication satellite fleets to the “strictly necessary number” and to put them in orbit only when old-outdated technology satellites are deorbited, according to the Outer Space Treaty (1967) – the Art IX [5], and the United Nations Guidelines for the Long-term Sustainability of Outer Space Activities (2018) – guideline 2.2(c) [6], requiring the use of outer space be conducted “so as to avoid [its] harmful contamination and also adverse changes in the environment of the Earth” and […omissis…] risks to people, property, public health and the environment associated with the launch, in-orbit operation and re-entry of space objects”.


All of these requests come from the heartfelt concern of scientists arising from threatens to be barred from accessing the full knowledge of the Cosmos and the loss of an intangible asset of immeasurable value for humanity. In this context, all co-signers of this appeal consider ABSOLUTELY NECESSARY to put in place all possible measures to protect the night sky right also on the legal side. It would be desirable to adopt contingent and limiting resolutions to be ratified with shared international rules, which must be adopted by all space agencies to ensure protection for astronomical bands observable from the ground. All of this to continue to admire and study our Universe, for as long as possible.


[1]  https://www.iau.org/https://www.iau.org/news/announcements/detail/ann19035/?lang

[2]  https://www.lsst.orghttps://en.wikipedia.org/wiki/Vera_C._Rubin_Observatory

[3]  https://www.eso.org/public/https://en.wikipedia.org/wiki/VLT_Survey_Telescope

[4]  https://panstarrs.stsci.edu/

[5]  https://www.unoosa.org/oosa/en/ourwork/spacelaw/treaties/introouterspacetreaty.html

[6]  https://www.unoosa.org/res/oosadoc/data/documents/2018/aac_1052018crp/aac_1052018crp_20_0_html/AC105_2018_CRP20E.pdf

[7] Simulated prediction of “only” 12k Starlink satellites in the sky: https://youtu.be/LGBuk2BTvJE and https://www.youtube.com/watch?v=z9hQfKd9kfA

[8] Visualization tool to find, plot and search satellite orbits: https://celestrak.com/cesium/orbit-viz.php?tle=/satcat/tle.php?INTDES=2020%2D001&satcat=/pub/satcat.txt&orbits=20&pixelSize=3&samplesPerPeriod=90

This appeal/petition can be signed by professional Astrophysicists & Astronomers, Technologists/Engineers , Collaborators & PHD Students involved in professional astronomical observations.

Note that (*) Such a sentence was added the 13/01/2020.

Note that (**) Such a sentence was added the 16/01/2020.

To sign/subscribe this appeal/petition you can follow this link.

Satellites’ Constellations at G7 obliterated!

At this link it is possible to find arguments and concerns related to the crowding of objects and satellites in the Earth’s orbit in the last G7 meeting regarding the sustainable use of Space activities.


They concentrated on space debris an how to avoid them. Unfortunately no member/speaker has identified the satellites’ constellations as the main danger in the future use of the Earth’s orbit in particular regarding the pacific use of the Low Earth Orbit as UN-COPUOS should safeguard and watch over. In particular it is important to note the military use of a large fraction of SpaceX satellites constellation ( https://spacenews.com/u-s-army-signs-deal-with-spacex-to-assess-starlink-broadband/ ) for US Army and AIR Force.

When politics fails and represents only a mirror for ladols!

All sheduled… from the beginning?

Here we post a new IAU call for porposals:

“The International Astronomical Union (IAU) invites proposals for the establishment of an IAU Coordination Centre for the Protection of Dark and Quiet Skies. The centre will foster the development of tools and procedures that can mitigate the impact of satellite constellations on astronomy, and will negotiate directly with the space companies and industries. Interested institutes or organisations are invited, individually or in partnerships, to submit proposals to host the centre.”


The mission of the centre can be summarised as follows:

  1. Coordinate the observation and measurement of the optical and radio interference caused by satellite constellations.
  2. Establish contacts with the space companies and industries involved in the construction and deployment of LEO satellites in order to discuss relevant mitigation measures.
  3. Foster and coordinate the study and testing of hardware solutions aimed at reducing reflected sunlight by the satellites and spurious radio emission in the side-lobes of the satellite transmitters.
  4. Interface with space agencies in order to get access to accurate and up-to-date orbital parameters of all LEO satellites.
  5. Coordinate the development of “smart” scheduling and/or detector operation software as well as specific artifact removal algorithms and distribute them.
  6. Provide suggestions for possible international regulations governing LEO satellites to the IAU Officers, in support of their pursuing the matter at COPUOS level.
  7. Maintain regular contact on matters of common interest with the other IAU Offices (OAD, OAO, OYA, OAE).
  8. Create and maintain a dedicated set of web pages under iau.org for disseminating information about the protection of dark and quiet skies from satellite interference.
  9. Organise thematic workshops (online and/or in person) as needed.

It is clear that all the time dedicated by IAU in conferences congresses and studies beginning from the half of 2019 to current days has revealed , as we have always thought, that there never has been the intention to oppose the development of megaconstellations.

This intention was quite clear when IAU decided to contract/negotiate directly with the companies for mitigation, instead of having the authorizations declared illegal by any official bodies in charge (US federal and or supreme courts or even at international).

With this call we understand how NEVER was thought to avoid the problem (known by early 2019), revealing that the satellite constellations affair is in fact nothing more than a political issue for the monopoly of the space by few nations over everything else (other countries, professions and scientific categories included!).

NOW A QUESTION arises from all international astronomical institutions:


If not contact us, follow and support our legal action, which today is the only one able to stop this mess!

IT IS NOT TOO LATE : just make declare by ICJ (or any US court) FCC authorizations to SpaceX unlawful and all the 1800 starlinks satellites will be deorbited!

Considerations on the impact of the satellites’ mega-constellations on ground-based radio astronomy

This post comes from the Pietro Bolli contribute to the related SAIt open discussion on impact of mega constellation on astronomy (HERE).

SpaceX simulated orbital density

The radio spectrum and its frequency spectrum management in which Radio telescopes operate generally shared with numerous other telecommunications services both for civil and military purposes.

A prerogative of radio astronomy compared to other services is the fact that it operates only receiving signals, so it is a “passive service”, so that it does not create interferences with other services. On the other hand, astronomical radio devices, are very high sensitive and this feature makes them extremely vulnerable any radio frequency interference from transmitting active services.

The harmonization between different services, ie the management of radio spectrum, is regulated very rigidly through multiple levels of control precisely to ensure a suitable use to all possible users. At national level, the Ministry of Economic Development instructs it and manages control, through the national frequency distribution plan (PNRF) and the various territorial inspectorates, operating by means and qualified personnel to verify the compliance of real radio systems accordint to the current legislation.

The last PNRF was approved on 5 October 2018 by decree of the Italian Minister of Economic Development and was published on the ordinary supplement n. 49 At the Official Journal of 19 October 2018, n. 244 [1] .The plan divides the radio spectrum into many sub-bands that are allocated to different remote control services; within the same band, different agencies regulate the coexistence between services. The radio astronomy, which falls on the radio communication services and recognized on an international basis, benefits in particular by some frequency bands with exclusive status in which no issue is allowed (Note 120 of the PNRF). The exclusive reserve is extremely important to ensure absolute calibration of all radio astronomy observations.

The PNRF is conforming to directives from international bodies responsible for the coordination of telecommunications standards, recipening in national legislation both radio communication rules (Radio Regulations) periodically modified from the final acts of the World Radiocommunications Conferences (WRC), both the measures approved by the European Union and the European Conference Agency on Telecommunications and Poste (CEPT).

At European level, CEPT has precisely the mandate to develop regulations and regulations on electronic communications, while worldwide, similar task is delegated to the International Telecommunication Union (ITU) of the United Nations Organization.

The various activities, CEPT and ITU carry out compatibility studies between different services in accordance with recognized methodologies and recruitments and approved by all radio communication services.

The European Astronomical Radio Community is represented in the international radio spectrum management context from the Committee on Radio Astronomy Frequencies (CRAF), an Expert Committee of the European Science Foundation (ESF), whose mandate is to maintain free from interference all frequency bands used for radio astronomical observations and represent the needs of the European scientific community for a continuous access and availability of radio spectrum for radio astronomy.

The CRAF, together with the twin organizations representing the astronomical radio community in other countries of the globe (IUCAF, RAFCAP and CORF ), then participates in the regulatory and technical tables of the bodies charged with coordinating the frequency bands for the various telecommunications services.

In addition to the bands allocated specifically with radio astronomy, astronomers are legitimate, not providing interference to other services, to collect radio waves from the universe even out of their bands, without however claimed to protect other services.

The astrophysic phenomena are not in fact limited to the bands dictated by the legislation and consequently to carry out point science it is also necessary to go out of bands officially allocated. The use of wide bands makes the astronomical radio receivers that are particularly susceptible to the problem of various types of non-linearities related to excessive power and the cumulative number of interference, up to compromise the quality of astronomical radio observation.

Just in an attempt to be able to exploit wider frequency bands possible by limiting the risk of receivers saturation, the radio observing infrastructures are regularly installed in remote areas. Furthermore, within agreements with local / regional / national administrations, telescopes radios often benefit from Radio Quiet Zone or areas without radio emissions or to the limit with emissions previously discussed and agreed with radio astronomers.

The 5th article of the introduction of the Italian PNRF establishes for example that: “According to Article 29 of the Radio Regulation, in order to ensure an adequate level of protection to the radio astronomy service, the MISE can establish all the technical devices necessary for Ensure protection to the radio astronomy stations of San Basilio (CA), Medicine (BO), Noto (SR), including the creation of areas of respect within which any type of issue by the active services is prohibited, even in the Frequency bands attributed to the radio astronomy service or only in specific frequency bands, used by radioactive stations plants, such as to compromise the observational capabilities of radio telescopes and the operation of radioactive receivers “.

Exclusion zone around the Medicina Radio Telescope.

Impact of mega constellations to radio astronomy

Recently, several concerns were generated for the impact that the so-called mega-constellations (i.e. Spacex, OneWeb, …), engaging the launch of thousands of satellites located at altitudes between 500 and 1200 km, in order to quantify the impact on the radio astronomy services.

According with ITU radio communications and because those systems fall into the category of non-geostationary satellites orbit (NGSO) with Fixed Satellite Service (FSS), which communicates between earthly stations located in certain positions carried out by one or more satellites in the same sky position.

A first study carried out by CEPT (ECC Report 271, [2]) addresses the compatibility of the Spacex and OneWeb constellations, operating in the bands 10.7-12.75 GHz (Down-link, Space-to-Earth) and 14.0-14.5 GHz (UP- Link, Earth-to-Space), with the services already present the immediately adjacent bands (these are called “incumbent services”).

For what concerns the radio astronomy service, the bands of interest are: 10.6-10.7 GHz (with secondary allocation 10.6 and 10.68 GHz and primary exclusive between 10.68 and 10.7 GHz) and the band 14.47-14.50 GHz (with secondary allocation). The first band is adjacent to the down-link band of the satellite service, while the second overlaps with the band intended for the UP-Link. The protection of the protection of astronomical radio bands is defined in the IUT-R RA.769-2 [3] recommendation and in the case of the down-link in question establishes that no emission of the NGSO satellites should exceed an equivalent density value of power flow (EPFD) equal to -241 dbw / m² in the band 10.6-10.7 GHz for more than 2% of the time (ITU-R RA.1513 recommendation).

The most critical down-link transmission than the UP-Link as there is the possibility that the emission coming from the satellite can be intercepted by the radio radio through its main lobe, whose maximum gain, taking a 100 m diameter antenna corresponds to about 81 dbi at 10.6 GHz. The study reported in ECC Report 271 concludes that to guarantee the aforementioned levels of protection, the satellites are obliged to deactivated all radio bands immediately adjacent to the astronomical radio band (ie channel 10.7-10.95 GHz), when the satellite is in visibility of an astronomical radio observatory accredited (such as those of inaf).

Instead for the up-link part, compliance with the limits imposed by the recommendation for the protection of the astronomical radio bands that are defined by the zones of richness around the radio telescopes to which the transmission in the band 14.47-14.50 GHz or to the limit allowed with emissions such as to guarantee the levels established in the ITU-R RA.769-2 recommendation.

The dimension of the grounds must be determined by any case on the basis of the technical characteristics of the antenna and the orography of the terrain. Depending on the emission levels towards the horizon of the terminals from the ground, which can be installed on fixed or mobile stations (for example ships), the CEPT report shows as possible ribbed designs between 200 E340 km around the antenna. The etc. Report 271 was approved on January 26, 2018 and was subsequently modified January 2019. Currently the CEPT and in particular the SE40 workgroup (Space Service Compatibility Issues) is updating this report to consider new technical parameters for these constellations.

In particular , in the latest version of ECC Report 271, an attachment has been added entitled intermodulation studies in which it shows how the possibility of receiving, through the main-beam coupling of the telescope radio with satellite main-beam, the emission from satellites in the band 10.95-12.75 GHz determine a compression of the active stages of the astronomical radio receiver compromising the protected band.

For this reason, Germany has recently established in issuing the license to the operators who to protect national astronomical radio stations the use of the frequency band 10.95-12.75 GHz by the satellites is not allowed in a radius area of ​​12.5 km around the astronomical radio site (“no down-link spot beams in this area”).

Note that the current report considers cases of a single interference source and non-aggregate interference cases or the most critical scenario in which several satellites transmit simultaneously.

The interest by the mega-constellation operators is also known to operate even at higher frequencies, both in Ka bands (between 18 and 30 GHz) and in the band between 35 and 50 GHz; In particular, for the latter band, the proposal (agenda ITEM 1.6) to authorize the use of various frequency portions between 37.5 and 51.4 GHz for satellite systems for the recent WRC of ITU.

This frequency interval is of primary importance for the scientific community, with various bands allocated to the radio astronomy service, and it will therefore be necessary to carry out new compatibility studies to guarantee protection.


[1] https://www.mise.gov.it/index.php/it/comunicazioni/radio/pnrf-piano-nazionale-di-ripartizione-delle-frequenze

[2] https://www.ecodocdb.dk/download/3ab9e6bc-0afd/ECC%20Report%20271.pdf

[3] https://www.itu.int/dms_pubrec/itu-r/rec/ra/R-REC-RA.769-2-200305-I!!PDF-E.pdf

[4] https://www.ecodocdb.dk/download/808b7529-e32a/ECCREP226.PDF

[5] https://www.ecodocdb.dk/download/368e9fdc-8685/ECCDEC0902.PDF

Light pollution from space junk (operating satellites included!)

In the Monthly Notice of the Royal Astronomical Society is possible to find a new accepted manuscript entitled “The proliferation of space objects is a rapidly increasingsource of artificial night sky brightness” of M. Kocifaj, F. Kundracik, C. Barentine, S. Bará, which is possible to find here.


The population of artificial satellites and space debris orbiting the Earth imposes non-negligibleconstraints on both space operations and ground-based opticaland radio astronomy. The ongoingdeployment of several satellite ‘mega-constellations’ in the 2020s represents an additional threat thatraises significant concerns. The expected severity of its unwanted consequences is still under study,including radio interference and information loss by satellite streaksappearing in science images. Inthis Letter, we report a new skyglow effect produced by space objects: increased night sky brightnesscaused by sunlight reflected and scattered by that large set of orbiting bodies whose direct radianceis a diffuse component when observed with the naked eye or with low angular resolution photometricinstruments. According to our preliminary estimates, the zenith luminance of this additional lightpollution source may have already reached∼20μcd m−2, which amounts to an approximately 10percent increase over the brightness of the night sky determinedby natural sources of light. This isthe critical limit adopted in 1979 by the International AstronomicalUnion for the light pollutionlevel not to be exceeded at the sites of astronomical observatories.
No Earth’s place can be hidden by reflected light!

The new study published in MNRAS photographs the dramatic and unexpected situation of light pollution from satellites and space debris. The night sky around the world is polluted well beyond the levels recommended by the IAU.

Satellites and debris, even invisible to the naked eye, increase the background brightness of the sky.

We are at levels around 10% of the natural value. Considering the “light pollution maps” at these levels the night sky is in the “blue level”: no more place is currently black, dark gray, light gray and dark blue areas!

Congratulations to the authors Kocifaj, Kundracik, Barentine and Bará for this very important result. Compounding the case is that the predicted megaconstellations have not yet been considered in the study, so this is the picture of the already dramatic current situation, destined to substantially worsen with the launch of tens(hundreds) of thousands of satellites in next years!

Another article can be found here: https://www.sciencemag.org/news/2021/03/study-finds-nowhere-earth-safe-satellite-light-pollution

A great book about Satellites’ Constellations

We would like to ubiquitously advertise the great work of one of our illustrious petitioners prof. Lawrence of the University of edinburgo who in his book entitled “Losing the Sky” delves into the serious problem of satellites’ constellations and the impact that these will produce at 360 degrees on our society.

Human unreasonableness, which does not take into account the harmful effects of some choices, pursuing as the unique objective the profit of multinationals, has its roots in the same modus operandi responsible for much worse devastation, such as climate changes & global warming as well as the pollution of the seas and atmosphere, causing irreparably the extinction of a large slice of flora and fauna present on this planet.

Even “Losing the Sky” represents, like other themed publications, a desperate scream in front of the awareness of the imminent crash not only of a profession, but of the whole humanity!

Rebelling is our duty not only as scientists but above all as human beings!

We also point out the foreword to the book of dr. Brian May, our myth! We’d be very proud if Brian would read and sign our “Appeal by Astronomers” petition as well as support our legal action initiative to block the deployment of these satellite fleets to the US FCC.

How to confuse GRBs with Satellites flashes!

Here is an important comment from Tomasz Kwiatkowski about a new interesting paper:

“There is an interesting paper on astro-ph, here is the link:


which shows how a satellite can be mistaken for a GRB. Should we soon have to introduce a new stage of the reduction of observations: de-satellizing?”

The Paper


GN-z11-flash was a signal from a man-made satellite not a gamma-ray burst at redshift 11


Michał J. Michałowski, Krzysztof Kamiński, Monika K. Kamińska, Edwin Wnuk


Long gamma-ray bursts (GRB), explosions of very massive stars, provide crucial information on stellar and galaxy evolution, even at redshifts z ~ 8 – 9.5, when the Universe was only 500-600 million years old. Recently, during observations of a galaxy at a redshift of z ~ 11 (400 million years after the Big Bang), a bright signal, named GN-z11-flash, shorter than 245 s was detected and interpreted as an ultraviolet flash associated with a GRB in this galaxy, or a shock-breakout in a Population III supernova. Its resulting luminosity would be consistent with that of other GRBs, but a discussion based on probability arguments started on whether this is instead a signal from a man-made satellite or a Solar System object. Here we show a conclusive association of GN-z11-flash with Breeze-M upper stage of a Russian Proton rocket on a highly elliptical orbit. This rules out GN-z11-flash as the most distant GRB ever detected. It also implies that monitoring of a larger sample of very high redshift galaxies is needed to detect such distant GRBs. This also highlights the importance of a complete database of Earth satellites and debris, which can allow proper interpretation of astronomical observations.

In Particular:

Brightness of Breeze-M debris as a function of distance from the observer from ourarchival observations with the RBT/PST2 telescope with an infrared cut-off filter (see Meth-ods). At the distance of around 15,000 km, corresponding to the distance for the MOSIFREobservations, the brightness was∼9.2mag, consistent with the MOSFIRE measurementtaking into account phase angle differences and the angular speed of the satellite.
The trajectory of Breeze-M debris in the field of view of MOSFIRE/Keck during theGN-z11-flash detection. The trajectory for the orbit corresponding to the date of the obser-vation is shown as a thick black line with1,2, and3σconfidence intervals shown as shadedregions. The trajectories for orbit elements calculated for days up to one week before and after the MOSIFRE observations are shown as green lines. The blue rectangles correspondto the positions and sizes of the slits used during the MOSFIRE observations. The position ofGN-z11 is shown as the black cross. Within1σof the best orbital model there are solutionscrossing the slit corresponding to GN-z11-flash and missing all other slits.

Chinese Constellations ready to go!

Geely is a new Chinese LEO constellation of an unknown number of newly authorized satellites (+/- 500 satellites shipped per year).

In few years the Low Earth Orbit could be totally saturated by artificial satellites.

Usually we tend to focus on the US constellations, but there are many more LEO constellations planned in China than currently authorized by the US FCC.

After all, the Chinese also have their own FCC which is called China’s National Development and Reform Commission (NDRC), so they do as they please with the authorizations.

Here are the chinese principal constellations:

  • The major governmental LEO constellation CASC called “Hongyan”
  • A secondary government LEO constellation CASIC called “Honyun” and “Xingyun” are currently planned in China;
  • then there is a third constellation called “GW”, which is not clear what it will do with 13 thousand satellites
  • another constellation called “Galaxy Space” for 5G in low orbit.
  • To these we add the Geely constellation for a more accurate GPS service than the current one in low orbit.

More info here: https://spacenews.com/automaker-geely-gains-approval-for-satellites-for-self-driving-constellation/

The Healthy Heavens Trust Initiative, HHTI legal action (of which our SAS Foundation is part) tends to push the inadmissibility of a national agency such as the US FCC to authorize such projects with global implications. But clearly agencies like the Chinese, Russian and Indian ones remain out of this discussion for now, even if a possible resolution would be easily extensible to them.

We will not get out of it until international laws will avoid that national countries to approve with their agencies and commissions this kind of projects, which must be exclusively coordinated and harmonized at international level.

In this contest it is good news that astronomical community is moving in a strenght politically way in order to delegate this difficult task to UNOOSA / United Nations, but it would also be appropriate to indicate a maximum number of satellites beyond which access to the sky will be compromises (and not just for our profession).

If we do not put / propose this ceiling as astronomers (e.g. a maximum of 10 thousand simultaneous orbiting satellites) it is likely that the United Nations, if and when they get this role, will end up putting an agreement on that one, which the national agencies have identified as their satellite’s infrastructure minimal target in order not to compromise the competition of the telecommunications giants.

And in a certain sense the astronomical community will have implicitly given its green light to whatever will be sent downstream of all this.

PS: Some scholars in the field argue that setting a number of satellites in LEO as a ceiling, although we shouldn’t be the one to identify this number, could play a much more prolific role in terms of international cooperation on a global public utility infrastructure and not only aimed at the business and competition of a few private companies and corporations. Therefore, the proposition of such an international action / coordination is desirable, especially if proposed by a strong and authoritative actor such as the international astronomical community; this could act as a driving force for this process of sustainable and cooperated access to the low orbit, preventing future damage instead of focusing on their minimization.

Hoping that all the boxes go to the right place we will continue to inform all of us about related news.

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