Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

ScoobyStoo

Tracking the ISS using a driven mount

Recommended Posts

Hi all,

I don't know if there are any other coders on this site, but I notice that Skywatcher have released an open source API to control their mounts.

skywatcher - SkyWatcher Api - Google Project Hosting

Now my Skywatcher 250PX GoTo Dob mount does a great job of finding and tracking almost everything of interest in the sky except stuff in LEO. I'd like to be able to observe ISS passes using high mags and my fag packet calculations tell me that the Skywatcher dob mount should slew fast enough to be able to track it across the sky.

Before I leap into writing a software application using the Skywatcher API to track LEO objects, I was just wondering if anyone was aware of any existing software that already does it. I'm surprised there isn't already a plugin for Stellarium or something which allows you to do it, but my Googlelations haven't yielded anything substantial.

Would appreciate any pointers anyone has...

Thanks

Share this post


Link to post
Share on other sites

The ISS moves really fast - I'm not sure that even on the fastest slew rate the EQ6/HEQ5 would be able to keep up.

I could of course be completely wrong :D

When I first read your post I'm wondering why the goto didn't like objects in LEO - but was OK with Taurus, Ursa Major etc... I did get there in the end though :)

Ant

Share this post


Link to post
Share on other sites

Yep, that'll be down to my mangling of the English language. Glad the ramblings made some sense though.

Will check my calcs but it does look like the mount can give me the angular velocity I need.

Share this post


Link to post
Share on other sites

I've just stepped out and looked up just as the ISS went by - I take back what I said... although the ISS is fast I think that the motors will keep up without too many issues.

Good luck :)

Ant

Share this post


Link to post
Share on other sites

Well, at its highest the ISS takes just over 6 minutes to go across the sky, from 10 degrees above one horizon to 10 degrees above the other. Call that 160 deg in 6 minutes. So you'd need to slew at 26.66 degrees per minute, or 107 times sideral speed. That should be possible.

Share this post


Link to post
Share on other sites

Yep. I'll have a more thorough Google around at the weekend and if I can't find anything then I'll have a pop at knocking up some code.

Share this post


Link to post
Share on other sites

I have seen this software pop up now and again when looking for similar stuff but never used it so not sure if any good or not

optictracker

Kevin

Share this post


Link to post
Share on other sites

Thanks for the links. Interesting stuff.

Doesn't look like either of these apps work with Skywatcher mounts though...

Share this post


Link to post
Share on other sites

I think the problem is (and I am trying to remember from posts in the various Yahoo groups about it) that when the EQ mounts try to change tracking rate above a certain rate, they need to stop and start at the new rate. That may be in the mount firmware, or not... cant be 100% sure about that.

The other problem may be that if its trying to do succesive "GOTOs" rather than just changing the tracking rate, the firmware in the mount will force a meridian flip when the next goto is beyond the meridian (sonething that a fork mounted scope doesnt have issues with)

Satellite tracker can work with LX200 mounts, and there is a EQMOD LX200 emulator that is supposed to work with EQ mounts, but I havent tried it myself. The guy who would probably know is Chris from EQMOD (who lurks on here every now and then :) )

Share this post


Link to post
Share on other sites

Hi there

Check this video out, I have managed to track the iss with an eq6 pro using the info on the film

The only bit that is not mentioned in the video is how to get the data updates from NASA, without this you won't find the satellites as the data from The Satellite Tracker program is Soooo out of date with the iss moving so fast the error over time is large, without the updates you will be wasting your time. as much as 180 Deg out (sometimes more :)) PM me for any help on this one

BI

Share this post


Link to post
Share on other sites

Ideally you need the tle's to be updated no later than an hour before - get a Spacetrak account setup - and the computer clocked synced to one of the NIST servers...

They used to use the shuttle to "boost" the ISS orbit ...

Peter...

Share this post


Link to post
Share on other sites
I think the problem is (and I am trying to remember from posts in the various Yahoo groups about it) that when the EQ mounts try to change tracking rate above a certain rate, they need to stop and start at the new rate. That may be in the mount firmware, or not... cant be 100% sure about that.

Yes that is true - it is the mount firmware. I have heard of some French astronomers who have managed to pacth the motor controller firmware to fix this!

The other problem may be that if its trying to do succesive "GOTOs" rather than just changing the tracking rate, the firmware in the mount will force a meridian flip when the next goto is beyond the meridian (sonething that a fork mounted scope doesnt have issues with)
When using EQMOD/EQMODLX in combination with satellite tracker we don't really do successive gotos except when puttin the mount into an intercept position. Once the satellite is intercepted and tracking only rate changes are sent to the mount.

Satellite tracker can work with LX200 mounts, and there is a EQMOD LX200 emulator that is supposed to work with EQ mounts, but I havent tried it myself. The guy who would probably know is Chris from EQMOD (who lurks on here every now and then :) )

EQMODLX takes the "LX200 GPS" output of satellite tracker and maps it to ASCOM type commands. So theory this would allow interfacing with any ASCOM driver that happens to support the MoveAxis and PulseGuide methods - though of course our main priority was to ensure interfacing with the EQMOD ASCOM driver.

Chris.

Share this post


Link to post
Share on other sites
Hi there

Check this video out, I have managed to track the iss with an eq6 pro using the info on the film

The only bit that is not mentioned in the video is how to get the data updates from NASA, without this you won't find the satellites as the data from The Satellite Tracker program is Soooo out of date with the iss moving so fast the error over time is large, without the updates you will be wasting your time. as much as 180 Deg out (sometimes more :)) PM me for any help on this one

BI

Glad to hear you managed to get some practical success out of watching my video. I'll add a comment/annotation about getting latest TLE data.

Folks should be aware that the synta mount motors are liable to make some quite strange sounds when tracking at these high "non standard" speeds (not your usual whispering sidereal tracking!) nothing to worry about though.

Chris.

Share this post


Link to post
Share on other sites
Glad to hear you managed to get some practical success out of watching my video.

Credit where credits due :)

BI

Share this post


Link to post
Share on other sites

I wrote software to track the ISS (or any other satellite) using the Celestron ALT/AZ mount. I used the 'rate' commands to track and not individual 'goto' commands. It would also download the orbit data so as to get the most up-to-date info.

I was also using the live image feed from the camera on the scope to maintain lock once it had 'phase-locked' the mount to the ISS.

However, the problem I had with the mount was that it's just to darned sloppy/inaccurate for such use, it was certainly fast enough (with ease), but sadly a total no-go with that particular mount.

Not had the Skywatcher mount so comment on those.

Here's a bit of source code for you incase it may be of some help to you.

Edited by Cath

Share this post


Link to post
Share on other sites

Maybe I should try this. What kind of camera do people usually use? My mount is capable of tracking it on its own without even the computer connected, so the camera thing is most important to me.

/per

Share this post


Link to post
Share on other sites

Ok, maybe i am being stupid or doing something wrong..... I "think" i have followed the steps detailed exactly from the above video....

When i click on "CONNECT" in satelite tracker i get an error message "Cannot Connect to Telescope". I have ASCOM simulator scope selected in the EQMODLX mount select and am connected.... I have a Virtual Com port 5 created and listening.... but still the same error when i hit connect... Can anyone point me in the right direction.....PLEASE!!!

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.