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An image of the Australian desert illuminates satellite pollution

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Re: An image of the Australian desert illuminates satellite pollution

#131

Post by genewitch »

testing22321 wrote: post #91
teamonkey wrote: post #87

Earlier quoted context omitted.

An astronomy photo can commonly require hours or even tens of hours of exposure time.

The noise from a single image of that duration would be unworkable. Even if there were no planes or satellites, nobody would take that as a single exposure.

your method of shooting the stars with a single long exposure is called a "wide-field" image. They're cool, but if you want to get any details of anything other than the milky way you either have to track or you have to stack. that's all there is to it.

I was going off memory, and with 50mm, it looks like 10 seconds is about when you start to get streaks, assuming no cropping. I have cropped sensors so even with a 10mm lens i can only do 12-15 seconds. I have a barn door tracker, and i know how to use https://www.autostakkert.com/

you need to have black frames for it to work, and ideally a lot of them (iirc at least a half dozen if not more) - because this is how the stacker knows which pixels are noisier than other ones, and also what the thermal noise of the sensor "looks like", at least the smarter stackers use it that way. you take a bunch of pictures with the lens cap on in a dark room at around the temperature you're gunna use it at.

real amateur astrophotography is done with CCD cameras, usually monochrome with filters (or a filter wheel), done in video mode, and the frames are processed after the fact. It takes hours with clear skies to make a decent deep field astrophotograph.

Re: An image of the Australian desert illuminates satellite pollution

#132

Post by yencabulator »

defrost wrote: post #117
CognitiveLens wrote: post #116

Earlier quoted context omitted.

I realize it's a nit-pick, but that is not at all the common definition of light pollution as it relates to night skies.

It falls under clause three: What is light pollution Light Pollution is the excess or inappropriate artificial light outdoors. Light pollution occurs in three ways: glare, light trespass, and skyglow. \* Glare is the bright and uncomfortable light shining directly to the observer that interferes with your vision. \* Light trespass is the unintended spill of artificial light into other people’s property or space and o…

Skyglow is when you see the horizon light up in the direction of a city, not the light reflecting from a satellite. Look at the photo in your own link.

Re: An image of the Australian desert illuminates satellite pollution

#133

Post by Miraste »

herewulf wrote: post #123
starkrights wrote: post #118

Earlier quoted context omitted.

You acknowledge the existence of things blocking , and can't imagine that there are people who want to see ? I feel like when is the sky, potential counterpoints can't be that far. For a direct response to your question: the sky and the stars beyond have been present and visible to every human, throughout all of history- how might different people feel about it becoming obstructed? Philosophically? Emotionally? Pragm…

> - Photographers / enthusiasts Sorry, but the ship has sailed. Fix your problems in software maybe. > - Astronomers / enthusiasts Every Starship launch should offer ride-share for a space based observatory. Astronomy will only improve with space based telescopes. Yes, spacecraft are expensive but so are Earth based observatories, but how does it look with launch cost removed from the equation? > - Those who enjoy na…

>how does it look with launch cost removed from the equation?

The Webb Space Telescope cost $10 billion, and has a 6.5 meter mirror. With the launch cost removed, it cost $9.5 billion.

The Extremely Large Telescope is located on Earth, costs a little over $1 billion, and has a 39 meter mirror.

The idea of completely replacing ground observatories with orbital ones is so infeasible it's not really worth discussing. If satellite pollution grows so extreme they can no longer function, those capabilities will simply be lost.

Re: An image of the Australian desert illuminates satellite pollution

#134

Post by defrost »

yencabulator wrote: post #132
defrost wrote: post #117

Earlier quoted context omitted.

It falls under clause three: What is light pollution Light Pollution is the excess or inappropriate artificial light outdoors. Light pollution occurs in three ways: glare, light trespass, and skyglow. \* Glare is the bright and uncomfortable light shining directly to the observer that interferes with your vision. \* Light trespass is the unintended spill of artificial light into other people’s property or space and o…

Skyglow is when you see the horizon light up in the direction of a city, not the light reflecting from a satellite. Look at the photo in your own link.

Let's assume I've read the link and have had discussions with both visual and radio spectrum astronomers and astrophysicists.

Starlink satellites pollute the night sky with both reflected sunlight and intended and unintended radio spectrum noise.

Manmade objects that inject light into an otherwise dark sky fit the category of skyglow, reflected sunlight tends to be sharper and less diffuse than atmospherically scattered ground lighting .. it's all extraneous human caused pollution from the PoV of telescopes.

Re: An image of the Australian desert illuminates satellite pollution

#135

Post by throwaway2037 »

threeseed wrote: post #31
macinjosh wrote: post #26

It is so polluted you need professional camera gear and processing of hundreds of photos together in order to show it. Get real. Internet access for poor, remote rural areas across the global is more important than convenient timelapse photography.

a) You can take these photos with a smart phone. b) In Australia we are rolling out fibre to rural areas and are testing 10Gb plans. Starlink will never come close to those speeds.

I thought that the Australia National Broadband Network mostly services rural areas with microwave dishes (shortwave radio)? Are they changing their strategy? The original point of microwaves was to reduce cost of laying (fibre) cable. I tried to Google for any recent news about this roll-out that you speak of. Do you have a link that you can share?

Re: An image of the Australian desert illuminates satellite pollution

#136

Post by genewitch »

defrost wrote: post #69
genewitch wrote: post #68

Earlier quoted context omitted.

This would be real simple to prove, Starlink Satelites downlink on the same band as Satelite TV so you can use the receiver from a dish that downconverts it to something a cheap dongle can handle and put that all inside a grounded, metal box in the bed of a diesel and just record spectrum. I was under the impression that actual space business people had ways of not leaking RF when flying over.

It's been proven by several teams already, eg: In new research accepted for publication in Astronomy and Astrophysics Letters, we discovered Starlink satellites are also “leaking” radio signals that interfere with radio astronomy. Even in a “radio quiet zone” in outback Western Australia, we found the satellite emissions were far brighter than any natural source in the sky. from: https://theconversation.com/starlink-…

> Although this IEMR abides by ITU-R guidelines, these intensities are large compared to the strongest astronomical radio sources in the sky and will therefore have the potential to disrupt astronomical observations at SKA-Low frequencies;

Sounds like the ITU-R messed up, regardless of why. starlink is 28% of the EIRP the ITU specified. And the "newer generation are a factor of 12 fainter".

We're talking micro. watts. of Effective Isotropic Radiating Power. with 0dBi antennas (unity gain).

I don't understand why they're using those oddball frequencies, but i haven't paid attention to band allocations in a long time. 159.4MHz is Land Mobile band plan - "business band 2 meters", and oh, 137.5 is "SPACE OPERATIONS". I almost want to guess that the 159.4 is a spur of something down around 39.9MHz, fourth harmonic or something. I don't see anything that would let starlink radiate there, unless they change frequencies over countries. Furthermore, it doesn't seem like the 159.4MHz signals will be a detriment to the facility in question, but merely possibly impinge on radio-astronomers.

I understand that these arrays are so sensitive that the RF they collect and process in the career of a scientist there is roughly equal to a cricket chirping once. or something. But microwatts are real tiny, too. Should be possible to put a notch filter at 137.5, or request space businesspeople to do intra-satellite on some other frequency.|

in fact, business idea: aim a yagi array where the satellites are as they pass over, can be done programmatically, or reactively - at least 4 sensors however far from the facility monitor the starlink downlink frequencies (not 137.5 and 159.4, but the ku band ones) - and then aim at the satellite.

I'll build it out with crap i have in my shed to prove it works if anyone is interested. If you know a satellite is in your second of sky, and you monitor, specifically, the 137.5 frequency with a separate, real sensitive antenna array, you can just drop the IQ/whatever from the radios for that timeframe.

This isn't rocket science, QRM and QRN will plague us forever. Thanks, Marconi.

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