9 replies to this topic

[Rac19]

After considerable trial and error I have managed to capture a grainy image of the ISS. There is a lot of room for improvement, to say the least. It was an achievement for me just to get the ISS in frame. The cringeworthy image is attached.

 

I have a Celestron Evolution 8 on a wedge and used a 0.5x reducer (effectively 1,000 mm FL) to widen the FOV to increase the chance the target being in the FOV. The tracking accuracy appeared to sufficient go to the Evolution 8's native 2,000 mm FL

 

I used SkyTrack in "leapfrog" mode which moves to successive positions on the ISS predicted path, 6 seconds apart, and pauses for the target to pass through the FOV. There is a continuous mode, but SkyTrack says that my connection via CPWI isn't responsive enough for that. When I attempted continuous tracking, there was a fair bit of wild slewing.

 

I am interested to hear of anyone else's experience with similar equipment and software (SkyTrack/CPWI).

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Edited by Rac19, 18 September 2023 - 07:43 PM.

[Winteria]

Congrats! 

 

I got continuous to work in SkyTrack by connecting to the mount through NexRemote, made a little write up a while ago here.

 

I'm also interested to see others' input.

[RMay]

Do you have an idea as to what your final image is expected to look like using that arrangement? Here’s an iPhone shot, one frame from a slo-mo video I took of a lunar ISS transit back in 2021. It’s not much, but it’s visible…

 

Ron

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[Rac19]

Do you have an idea as to what your final image is expected to look like using that arrangement? Here’s an iPhone shot, one frame from a slo-mo video I took of a lunar ISS transit back in 2021. It’s not much, but it’s visible…

 

Ron

I was expecting better than what I got, more like the link in post #2. In that example continuous mode was used and you can see that the exposure was fine tuned in the first second or so.

 

I am going to persevere with leapfrog mode for a while at 2,000 mm FL. If a C6 can achieve the results in post #2, my Evolution 8 should be able to do at least as well. I have lots of issues using the HC, it it has problems with me. The HC is required for continuous mode.

 

Your image in post #3 is good too. It had occurred to me that waiting for a moon transit was an option, it just doesn't happen very often?

Edited by Rac19, 18 September 2023 - 09:49 PM.

[RMay]

Wow, well, that image you referred to is terrific, for sure.

You can use an ISS tracker app to locate lunar and solar transits from your area, or those nearby. I will be shooting another solar transit in about three weeks from my neighborhood.

Here’s what I use…

https://spotthestation.nasa.gov/

I think it’s much easier to have the Moon as a backdrop to try and capture the ISS, but I’m limited to using my iPhone.

Ron

[Rac19]

Wow, well, that image you referred to is terrific, for sure.

You can use an ISS tracker app to locate lunar and solar transits from your area, or those nearby. I will be shooting another solar transit in about three weeks from my neighborhood.

Here’s what I use…

https://spotthestation.nasa.gov/

I think it’s much easier to have the Moon as a backdrop to try and capture the ISS, but I’m limited to using my iPhone.

Ron

Thanks, that's what I plan to do but I can't see any transits in the near future.

 

I see the ISS as a new challenge to follow on after the planets and DSOs. It is proving to be just that.

[ButterFly]

Congrats! 

 

I got continuous to work in SkyTrack by connecting to the mount through NexRemote, made a little write up a while ago here.

 

I'm also interested to see others' input.

You can use CPWI as well.  I put a program together to automatically plate solve align it, specifically for use with SkyTrack in mind.  If you create a set of pass points through SkyTrack, you can drag and drop those to get alignment points into CPWI's model as well.  Watch it carefully the first few runs to make sure you have no cordwrap issues or leg strikes, then it's automatic once you've got a good set of initial problem free points.  A ten point model takes only a few minutes.  Adding the particular passes' points takes a few more.

 

Be aware that polar alignment matters for EQ mounts and leveling matters for Alt/Az mounts.  SkyTrack uses MoveAxis commands, which are mount oriented.  The better the polar alignment (leveling), the better the mount motions correspond to sky motions.  For example, if your polar alignment is off, moving the mount RA axis will move along the sky's RA direction as well as a little bit in the Dec direction.  That's a slight drift you can nudge with the fine timing controls, but it's easier to just start off with a better baseline.

 

Don't neglect CSS.  It also shows lots of details.

[ButterFly]

From your previous post:

 

 

Before the pass:

 

I check https://www.time.gov/ to see how much my computer clock is off by. If it's off by more than maybe a half-second, I'll sync it in Windows Date and Time Settings.

Just use an NTP server instead.  I use Meinberg NTP.  It communicates with a bunch of time servers to get within a millisecond, and sets the time, without any user intervention.  I just check to make sure it's actually communicating with servers.

 

Beware of clock drift.  Once you send your mount the time, it will drift after that - your mount is keeping time rather than the computer, even with CPWI.  With a next morning pass using a previous evening alignment, the time can be off by half a second to a few seconds.  For best results, do the alignment soon before your intended pass.

[Winteria]

You can use CPWI as well.  I put a program together to automatically plate solve align it, specifically for use with SkyTrack in mind.  If you create a set of pass points through SkyTrack, you can drag and drop those to get alignment points into CPWI's model as well.  Watch it carefully the first few runs to make sure you have no cordwrap issues or leg strikes, then it's automatic once you've got a good set of initial problem free points.  A ten point model takes only a few minutes.  Adding the particular passes' points takes a few more.

Doesn't CWPI have to connect to SkyTrack via ASCOM, ie is slower than Legacy? I had a look through your thread - cool software - though I haven't found the need for a pointing model for ISS lately.

 

Don't neglect CSS.  It also shows lots of details.

Yes - for the folks further south. Maxes out from here at 27° though I've still tried.

[ButterFly]

I haven't noticed a difference in speed between legacy and ascom.  The update frequency setting is the same in skytrack for both.