ISS tracking question

[Kaptain Klevtsov]

Been wondering about snapping the ISS and I came up with a hair brained scheme involving a custom speed controlled EQ mount to track the thing across the sky. The initial plan falls down though if I can't do the equivalent of polar aligning the mount. Anybody got any ideas about how one would go about this, and if it remains the same over time?

Kaptain Klevtsov

[SteveL]

If what remains the same over time? The altitude changes (the shuttle gives it a nudge back into a higher orbit when it visits), and I guess that would affect its angular velocity.

[Kaptain Klevtsov]

Sorry Steve, I wasn't clear. What I'm wondering is the angles (Alt. & Az.) that I need to have the "RA" axis of the mount at as the ISS clearly doesn't orbit around the Earth's axis or it would fly over the equator all the time. The axis of the ISS is therefore somewhere different to the Earth's axis so my polar aligned mount will be pointed in the wrong direction to track the ISS. Looking at websites it appears to fly in a sine wave pattern when projected onto a map of the Earth so I could nearly work it out from the pictures if I knew how, but that doesn't tell me if the angle would be good for more than one night.

Hope this makes more sense.

Kaptain Klevtsov

[SteveL]

I think this will be tricky.. its orbiting the earth, but the earth is rotating underneath it at the same time.

I just use Satellite Tracker software for my mount, and thats usually pretty close (According to the SatTrack maillist, it can be made to work on EQ mounts)

[George]

Wouldent something like starrynight pro track it?

[SteveL]

No... SNP would only point your scope where it is RIGHT NOW but wouldnt contsantly update the scope to point at the orbit. If you select an object in SNP, all it does is slew the scope to that position, and the scope does the tracking (at sidereal or Lunar rates). Satellite Tracker sends constant readjustments to the scope to position it, because the ISS is not moving at sidereal rate, nor is it moving in a constant RA drift.

[proflight2000]

I tried the tracking software with my heq6 a while ago and basically it went nuts, it would start off all ok then basically I think the scope was unable to cope not the software.

[SteveL]

I did read somewhere that the *EQ mounts are unable to keep up as the ISS passes near the zenith. Hell, when my NS8GPS is tracking, the mount sounds ike its going to explode!