Quote:
Originally Posted by RNajarian
but I was wondering, is it possible to have my setup locate and real-time track (larger) Earth satellites in orbit with my computerized mount?
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Technically, yes, the mount is 100% capable of tracking satellites.
2 problems:
1) The software isn't designed to run at speed like that. The 5SE (and nearly anything else out there) is limited to about 3 degrees per second at fast slew, which is an unstable speed. Fastest stable speed (fully controlled by encoder feedback) is generally 2 degrees per second. That means it would take 90 seconds to go horizon to horizon.
2) The software is designed to override the Earth's rotation, which is a simple calculation. Satellites travel in complex 2 dimensional directions, and the software inside the telescope really isn't up to the task. There is external software that can interact with or override the mount, but I'm not sure if there's any Sky Portal compatible stuff. For sure there's programs on the PC that can run via Nexremote or Stellarium or something.
You'll need for sure the 2 line ephemeris/ephemerides for any satellite, this is a series of numbers in a defined order that software uses to calculate the projection of the orbital parameters. With that, the software knows how to point and move to track a satellite, but it remains to be seen if something like the 5SE is stable enough to pull it off.
Here's an example for the ISS:
TWO LINE MEAN ELEMENT SET
ISS
1 25544U 98067A 19298.54632874 .00016717 00000-0 10270-3 0 9005
2 25544 51.6402 74.8919 0006900 187.3660 172.7390 15.50181118 35473
These number CHANGE and sometimes are not correct. Generally, satellite data is not publicly available, so the 2-line data is calculated from observations and the orbital parameters are then estimated. If a satellite makes a tiny course correction, the parameters might be significantly off afterwards.
The same 2-line data is used for comets and asteroids (and actually, for planets and the Moon...) so the Celestron technically can read them, but the software doesn't run at a high enough resolution or sample rate for satellites.
Finally, you won't see anything but a bright dot, even with the camera and tracking. The ISS is HUGE and it's only about the same apparent angular size as Jupiter under the best of conditions, most satellites would be un-resolved even with a telescope.
The other problem is that unlike planets and such, a satellite changes distance dramatically as it goes from the horizon to overhead to horizon. here's an example for the ISS on a particularly good overhead view:
Event Time Altitude Azimuth Distance (km) Brightness Sun altitude
Rises 18:48:10 0° 221° (SW) 2,344 1.1 -15.1°
Reaches altitude 10° 18:50:16 10° 224° (SW) 1,481 0.0 -15.6°
Maximum altitude 18:53:33 61° 305° (NW) 471 -3.4 -16.4°
Enters shadow 18:55:04 28° 17° (NNE) 802 -2.7 -16.7°
So, it changes between 470 kilometers at it's closes to 2300 kilometers away. At's 100 meters across at the largest measurement, so that is:
arctan (100/470,000)=44 acrseconds to arctan(100/2300000)=9 arcseconds.
All of this is why it's hard to find info on tracking satellites online. Most people who get into it build purpose built mounts with high speed steppers and homemade control systems.
Oh...you better have that that telescope alignment dead nuts on as well, everything is dependent on the software calculating the orbital parameters on the fly as referenced by the true position of the scope...