Sitrec Night Sky and Starlink Development

Mick West

Mick West

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  • Added accurate terminator (light and dark regions of the globe and the border between them)
  • Improved right-drag navigation when using a globe
2023-10-08_16-26-47.jpg


https://www.metabunk.org/sitrec/?sitch=pvs14
 
2023-10-09_12-41-24.jpg

https://www.metabunk.org/sitrec/?sitch=pvs14
I now show both shadowing and flaring of satellites.
Shadowing makes them small if they are in the shadow of the earth. (really they would be invisible)
Flaring assumes the reflection is off the ground-facing flat bottom of the satellite, an calculates the angle between the LOS from the camera reflected off this and the rays of the sun. If <3 degrees it uses this to scale up the satellite.

Works pretty well, but (as expected) not perfect since we don't know the precise angles of the satellites. I'm also not accounting for the elliptical Earth, or atmospheric refraction.

URL for Starlinks
https://www.space-track.org/basicsp...AT_ID,EPOCH/format/3le/OBJECT_NAME/STARLINK~~
 
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wow, that is truly fantastic.

can I disable the globe view & the video view so it can be viewed in the mobile version of Chrome? and then load in the latest TLEs? because if so... then we'll have a mobile app that could show flares in real-time... and that would be absolutely epic. ✅
 
flarkey said:
wow, that is truly fantastic.

can I disable the globe view & the video view so it can be viewed in the mobile version of Chrome? and then load in the latest TLEs? because if so... then we'll have a mobile app that could show flares in real-time... and that would be absolutely epic. ✅
Click to expand...
Eventually. Mobile is a bit fiddly. But I'll give it a go.
 
2023-10-09_16-05-47.jpg

I've added some arrows showing the vector from camera to satellite, and then to the sun.

Also added a slider for the angle at which the sats flare. I had it at 3 for PVS14, but in the "Night Sky" sitch that means we get no flares unless it's bumped up to 5.
 
Somewhat cosmetic (but significant) updates:
  • I use an ellipsoid model for visual occlusion (i.e. the displayed globe is squished at the poles)
  • I use the wgs84 polar radius for actual occlusion tests
  • I have a "penumbra" region which is just a function of the sagitta formed by the ray from the satellite to the sun, as it intersects the globe. This is used to smoothly fade the brighness of satellites as they go from light to dark.
  • This is combined with the flare calculation, so everything is smoother, and closer to reality.
  • I've changed the rotating and panning to be
    • More like Google Earth
    • Less buggy
  • Removed the random crosshairs, unless they are needed.
  • Fixed the Hulsey sitch so it's much close to reality.
 
  • Added a "Night Sky" sitch (old Night Sky is now "Area 6") that's just the globe
    • Uses current Starlink TLE
  • Improved moving around the globe with "L"
  • Added Show/HIde "Flare Region"
You can (somewhat clumsily) use this to check recent Starlink events.

https://www.metabunk.org/sitrec/?sitch=nightsky

Fun demo, moving around and showing where the flares are.

 
Mick West said:
  • Added a "Night Sky" sitch (old Night Sky is now "Area 6") that's just the globe
    • Uses current Starlink TLE
  • Improved moving around the globe with "L"
  • Added Show/HIde "Flare Region"
You can (somewhat clumsily) use this to check recent Starlink events.

https://www.metabunk.org/sitrec/?sitch=nightsky
Click to expand...

Wow, that's fantastic. I did a quick comparison with Heavens-Above and the predicted orbital visibility seems spot on. Although I'll have to wait until the end of October before the flares are visible for me. Looking forward to trying it in real time.
 
https://www.metabunk.org/sitrec/?sitch=nightsky

  • Increased brightness of sunlit satellites below 450km, to make "trains" more apparent.
  • Fixed camera positioning with L and the Lat/Lon in UI so it works all around the globe
  • Brightened the dark side of the Earth, so you can see locations.
  • Made "Nightsky" sitch use full screen (globe on left, camera view on right)
 
  • Start time on the NightSky Sitch is always the current time (on page load). You can adjust this. Or refresh the page to get a new current time
 
Whats the green blob above the sun in this screenshot and in the starmap?? Venus?

1697374373249.png


If so, then I assume the red dot left of the sun is Mercury?

Edit - Duh - I turned on the starnames and that answered all my questions.

1697374569254.png
 
  • The Night Sky sitch now attempts to get your approximate location from the browser. You can choose not to let it and it will use the default.
 
  • NightSky sitch now lets you drag and drop in a .tle (or .txt) file and it will replace the current TLE with that one. So you should be able to do fairly arbitrary Starlink reconstructions.
 
  • Limited zoom out so you can always see the planet
  • Added display of local time along with UTC time.
 
In the Night Sky sitch.
  • Added ability to drag and drop a URL to a TLE hosted on Metabunk (i.e. a link to an attachment)
  • Added permalink generation button, which creates a long URL allowing you to share a particular setup - including a TLE loaded via a link (files dropped in will not be shared)
Example:

https://www.metabunk.org/sitrec/?sitch=nightsky&data=~(lat~38.67~lon~-121.18~alt~822~startTime~'2023-02-15T02*3a37*3a09.343Z~az~6.2~el~32.1~fov~32~p~(x~-74451.69048339054~y~2072629.417102186~z~2623864.1037578946)~u~(x~0~y~1~z~0)~q~(x~-0.3078711525394947~y~-0.023285761895267792~z~-0.05226623331457471~w~0.949705937425932)~f~1042~pd~true~dragURL~'https*3a*2f*2fwww.metabunk.org*2fattachments*2f5-4prelaunch-txt.63617*2f)_
 
  • PTZ (Az, El, Fov) parameters in Look View now controllable with the mouse, which is much more convenient than the GUI.
 
Bug - Sitrec nightsky is running at about 1/3 of realtime. (it does this on both my PC and mac, but admittedly they are old and have a slow internet connection , so it might just be me. Happens in Chrome & Firefox on mac and in Edge on PC)
 
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flarkey said:
Bug - Sitrec nightsky is running at about 1/3 of realtime. (it does this on both my PC and mac, but admittedly they are old and have a slow internet connection , so it might just be me. Happens in Chrome & Firefox on mac and in Edge on PC)
Click to expand...
Yeah, the addition of thousands of satellites puts a strain on older machines. The internet is not used after it loads. Next week I'll focus on both optimization (making it smoother, and your laptop less hot) and time syncing (so it's locked to the clock for time updates)
 
NorCal Dave said:
So, I can open the program and allow it to use my location, then figure out where/when I might see a Starlink array?
Click to expand...
You can edit the date and time to give you an accurate view of the sky at any time, so yes. You'll need to do some tweaking to find out if anything is visible for your location.
 
BUG: Permalinks show incorrect camera for people in different locations (or people who blocked their locations)

This mean's @flarkey's permalinks will work for him, but not for me.

After I fix this, older permalinks will need to be re-exported by the person who made them so they work for everyone else.

In other news, I tidied up the excessively large Venus, and the random pentagons
 
Mick West said:
BUG: Permalinks show incorrect camera for people in different locations (or people who blocked their locations)

This mean's @flarkey's permalinks will work for him, but not for me.

After I fix this, older permalinks will need to be re-exported by the person who made them so they work for everyone else.
Click to expand...
Fixed! (Hopefull, it was a little fiddly)
Also now stores the Show/Hide state for Sun Angle Arrows, Flare Region, and Satellite Names.

So https://www.metabunk.org/u/95cDfQ.html

should look like:

2023-10-31_17-22-07.jpg
 
A fun idea Mick takes his starlink app makes a mobile version that uses GPS location altitude and time as well as compass and orientation sensors to do an AR camera overlay of starlink flares in real-time.
 
jarlrmai said:
A fun idea Mick takes his starlink app makes a mobile version that uses GPS location altitude and time as well as compass and orientation sensors to do an AR camera overlay of starlink flares in real-time.
Click to expand...
Yeah, I need at least to make it a bit more mobile friendly. The might be some limits because it's a Web app.
 
It still seems to be running very slowly on every pc I try, does it need a 0.1s refresh rate? Between 1 to 5 secs would probably do most users.
 
flarkey said:
It still seems to be running very slowly on every pc I try, does it need a 0.1s refresh rate? Between 1 to 5 secs would probably do most users.
Click to expand...
Heck, I'd like it to have a 0.01666s refresh rate. Are you running Chrome? What's the spec of a typical PC you're running it on.

It runs reasonably fast on my 2.6Ghz 2016 Apple laptop.

What's the speed difference between satellites on and satellites off?

There's some very significant optimizations I can do with displaying the satellites, but it will take a few days of work.
 
  • Laptop running Edge: It is noticeably faster - With satellites off it is close to RT. With satellites on it is about 0.7 RT.
  • Old Mac running Chrome: slightly faster, about 0.8 RT.

Bug: Satellite names not showing.
 
flarkey said:
  • Laptop running Edge: It is noticeably faster - With satellites off it is close to RT. With satellites on it is about 0.7 RT.
  • Old Mac running Chrome: slightly faster, about 0.8 RT.
Click to expand...

Try it now (satellite names still broken, but should be noticeably faster)
 
flarkey said:
Some weirdness with sun diretcion arrows when over the rockies....
Click to expand...
This is because I display the Earth as an ellipsoid, but the collision checks use a sphere with the smallest earth radius. So the equatorial bulge in the displayed globe is overlapping some lines of sight.

It can be fixed, but it's slightly fiddly due to the mix of coordinate systems.
 
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