Need a 'What is above me now' view

[jensenbox]

Use the geolocation of the browser to assist - either by IP or just the standard HTML5 sensor.

[thkruz]

The satcruncher webworker has the framework for az, el, and range calculations from a lat long. You could modify the satcruncher to have a binary "inview" variable and then change the colorscheme to highlight things that are "inview".

[louiselessel]

Hi @jensenbox - were you able to solve this? I need this view as well.
Specifically I need a "What are the closest 100 satellites to this latitude, longitude (40.730610, -73.935242) on earth" - view,
or a "What are the satellites within a radius of 200 km, to this latitude, longitude (40.730610, -73.935242) on earth"

I looked at @thkruz suggestion, but I cannot see how I would write that in the satcruncher unfortunately.

[thkruz]

Let me be more detailed on my earlier response:

Below the declaration for satPos, add the following and adjust to your needs:
var defaultGd = { latitude: 41.015, longitude: -71.125, height: 0.54 };

Below var x,y,z,vx,vy,vz,alt; add:
var azimuth, elevation, rangeSat;

Add the following code:
positionEcf = satellite.eciToEcf(pv.position, gmst);
lookangles = satellite.ecfToLookAngles(defaultGd, positionEcf);
azimuth = lookangles.azimuth; (You might not need this for a telescope)
elevation = lookangles.elevation;
rangeSat = lookangles.rangeSat;

That will allow you to calculate AER for each satellite relative to your lat/long. From there you could add an if statement along the lines of:

if (elevation >= 0 && rangeSat < 200) then to filter satellites currently closer than 200km and pass them back to main.js

NOTE: You will need to create a new array both in sat.js and sat-cruncher.js to pass back and forth. Then you would need to create a new if statement in color-scheme.js to change the object's color.

Let me know if you hit any more road blocks. I forked this project at https://github.com/thkruz/keeptrack.space/ and have the code for this included if you need a reference point (copying and pasting it will almost surely fail). There is simply no way around these changes for what you are asking for. If you don't want to/can't then it might be best to look for another library to do the calculations on-demand instead of in the webworker.

Best of luck.

PS. Geolocation requires https in most modern browsers.

[louiselessel]

Thank you @thkruz !

This worked like a charm, just one question then: how would I access the satellites id or type from here?
I am doing:

if (elevation >= 0 && rangeSat < 2000) {
arrayOfSats1.push(satellite);
}
However that is all of the data, and I can't seem to find the id from in there? Is it another value that I should be pushing here?

thank you so much!

[thkruz]

@louiselessel you can add

extra.SCC_NUM = pad0(satData[i].TLE1.substr(2, 5).trim(), 5)

function pad0 (str, max) {
    return str.length < max ? pad0('0' + str, max) : str;
};

to satcruncher around line 19 (put the function towards the bottom if you want)..

Now you can use the SCC_NUM property to filter inside satcruncher AND it will get passed back to satSet so that you can use it inside the main program too. Something like

if (arrayOfSats1[i].SCC_NUM == '25544')

It is probably more optimal to push "i" or satCache[i].SCC_NUM instead of the whole satCache[i] object since the satCache exists in satSet.js as well with the same id and SCC_NUM properties. The postMessage call can be resource intensive on slower machines.

I pad 0s and use strings for consistency sake when dealing with other external databases that may or may not call 00005 instead of 5.

[louiselessel]

Thank you @thkruz.