How can we look at sattelites with a telescope if they are moving so fast in the orbit?
RATNIK asked:
Following this link you will see an image of the ISS seen through a telescope: http://antwrp.gsfc.nasa.gov/apod/
- Now since the ISS is orbiting the Earth at great speeds, how are we able to see it without having to constantly adjust the telescope to accommodate for ISSs’ movement?
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Following this link you will see an image of the ISS seen through a telescope: http://antwrp.gsfc.nasa.gov/apod/
- Now since the ISS is orbiting the Earth at great speeds, how are we able to see it without having to constantly adjust the telescope to accommodate for ISSs’ movement?
March 11th, 2009 at 5:37 am
The orbit of the ISS is well understood. There are tracking telescope mounts that can track arbitrary orbits, not just stars, planets and the Moon. And, the ISS is pretty bright, so short duration images can freeze motion.
I’ve tracked the ISS at 48x in my dob telescope by hand. It’s not easy. I didn’t quite get this resolution - but i could make out the solar panels and the central body.
March 12th, 2009 at 11:27 pm
SIMPLE:
You attach a motor drive to the telescope so that the telescope is swung across the sky at the same rate that the ISS is moving.
March 16th, 2009 at 12:52 am
NASA has really good tracking equipment so they can do it. You would probably not be able to do it.
March 16th, 2009 at 5:58 pm
Well, you DO have to continually move the telescope to compensate for the movement of the space station. To get the kind of image you see on the NASA site you need high magnification and a computer-guided telescope since you would never be able to track it by hand accurately enough. You also need a video camera and lucky imaging software to stack the images you get to increase the image quality.
If you can find a raw video of the space station used to create an image similar to the one you see you’ll see that even with computer guidance the ISS drifts about in the field of view. That is one of the things the software has to compensate for. In short getting a picture such as that uses several moderately advanced techniques and requires a good deal of skill.
March 19th, 2009 at 8:37 pm
Tracking the moving ISS while taking such pictures IS the main challenge. But it can be done. Some people have even done it by manually moving the telescope by hand to follow the ISS across the sky. The amount of skill needed to do that boggles the mind. My hat is off to suitti.
March 20th, 2009 at 6:28 pm
Tracking a particular satellite requires either specialized computer software and a goto telescope, or a pair of people working together: one looking through the finder to locate the moving satellite and another looking through the main telescope’s eyepiece.
I have many times tracked what I call “accidental satellites.” I’ve been observing with my Dobsonian, which has a very smooth mount, when a satellite has entered the field of view. You’d be surprised how frequently this happens. Once the satellite is in the field, it becomes quite easy to track with a good smooth mount. I do this all the time.
[Edit] This is a better link to this image, as the one you gave only works for a few more hours:
March 22nd, 2009 at 1:36 am
For best results, you need computerized tracking to aim the telescope and electronic image stabilization (fuzzy logic) to keep the target in the center of the frame. To eliminate atmospheric distortion, you need more sophisticated software and perhaps a laser guide star.