Help needed :(

[Karbon (Andrew)]

Hi all. I'm very new to astrophotography. I bought a 5" Newt a couple of years ago, and got an SV305 camera and took some videos of Saturn & Jupiter that I stacked into some images I was quite pleased with.

I've since then been saving up for a while, and finally bit the bullet and got a Star Adventurer GTi with a Redcat 51, and an ASI120MM Mini + WO Uniguide (32mm F4). I'm using a laptop with the SynScan Pro app, along with APT and PHD2. However, I'm having a lot of trouble with it.

It feels like there's something very wrong with the mount. No matter how I align it, it can't seem to slew to targets accurately, nor track particularly accurately for that matter. I've performed a polar alignment, although I don't know exactly how accurate I am with it given I'm in Melbourne Australia and I can't see any stars through the polar scope, let alone the octans. I've tried using APT's Polar alignment with plate solving, and it can plate solve okay, but the adjustments it suggests are often wildly off. E.g. trying to point me to 160 degrees, rather than true south (edit: I think this was mostly due to using the SV305 for plate solving; when I switch to the 120MM Mini it was more accurate and consistent). Also, when using APT I can plate solve the current target, then use APT to goto a new target, plate solve again, slew again, and repeat this about 3-4 times before it will get me to the right location.

If I perform alignment with the app directly, when I slew to the next target it can be out by anything from 5 to 20+ degrees.

Another example of weird behaviour is when I tried to calibrate PHD2. It consistently shows an orthogonality error of 35-60 (see image). You can see from the tracking that one axis seems to go at 45 degrees to the other; it's quite consistent in that error also.

https://imgur.com/a/Z9QnQba

Any suggestions? As mentioned, it feels like something is wrong with one of the axes of my mount, but then given I'm so new I'm quite willing to believe that I've completely missed something.

FWIW, I have set my location correctly (both in SynScan and APT), so it's not that...

[croweater (Richard)]

Hi Andrew. Have you set your time correctly. I believe in the procedure you would set time and also answer whether daylight savings or not. Worth checking.
Cheers, Richard.

[xelasnave]

And maybe the date?
It is probably Month, then day...easy to miss

[Startrek (Martin)]

Here’s some procedures for Skywatcher mounts with Synscan including setting tripod to true south , Synscan polar alignment, various PHD2 procedures etc. etc ….
Don’t know much about this new mount but I believe you can use the Synscan handcontroller as well for Goto ( rather than the app )
Synscan has an inbuilt polar alignment routine that doesn’t require a view of the pole ( been using it for 5 years )
PHD2 has a polar alignment routine as well ( used it recently)
I use much bigger mounts EQ6-R and EQ8-R pro mounts but hopefully some of this information is relevant to your light weight portable Skywatcher mount

Good luck

Cheers
Martin

[Karbon (Andrew)]

Thanks for the suggestions all. I'll double check my settings for date and time; I believe I set the timezone in the app, but I think it picks up date and time from the laptop's settings. I'll check all the settings again though.

I'll also check the PHD2 polar alignment; it'll be good to have independent methods of verifying alignment.

I'm still confused by the PHD2 calibration though; has anyone seen anything that extreme before? I wouldn't have thought a slight polar misalignment would cause such a bad orthogonality error.

[Crater101 (Warren)]

There have been a few issues with the GTi mount. I had one briefly and returned it. However, others have had one that have performed very well straight out of the box.


There is a long thread here...
https://www.iceinspace.com.au/forum/...d.php?t=197791


...that you will find addresses several of the issues you raised, and offers some other potential solutions.


Good Luck!

[Karbon (Andrew)]

Well, with no surprise to anyone (including me), user error does indeed seem to be the issue here. Thanks again for the help; using PHD2 to polar align gave me far better and consistent alignment.

I was able to get it tracking and I can't complain with these results: https://imgur.com/a/T6DQeeD

Now I need to learn how to process my photos, but that one I can deal with...

Thanks for that thread link Crater101. It's a bit concerning to hear that the new mount I bought might have systemic issues, but from the tracking above it doesn't seem to be a problem for me atm. I was able to take 15 minute photos with nice round stars, so unless it degrades significantly I think it'll be okay for me. I'll post to that thread if it changes...

[Crater101 (Warren)]

Originally Posted by Karbon

Thanks for that thread link Crater101. It's a bit concerning to hear that the new mount I bought might have systemic issues, but from the tracking above it doesn't seem to be a problem for me atm. I was able to take 15 minute photos with nice round stars, so unless it degrades significantly I think it'll be okay for me. I'll post to that thread if it changes...

Pleased to hear that you didn't get a bad copy of the mount. I look forward to seeing the results in the future! All the best.

[Karbon (Andrew)]

Originally Posted by Crater101

Pleased to hear that you didn't get a bad copy of the mount. I look forward to seeing the results in the future! All the best.

Okay, well here’s my first effort. I know I still have much to learn, and put no effort into composition, and have done very little processing, and the colour and detail is poor (I only have an SV305 for now), but I’m pretty happy with how this turned out.

Thanks again everyone who offered help. I didn’t think it’d be as simple as better polar alignment, so I’m very glad to have the suggestions to try other methods.

https://iili.io/HCNOEAP.jpg

[Drac0 (Mark)]

Okay, well here’s my first effort.

It looks like a Tarantula so I would call that a success for your first go.

Cheers,
Mark

[AstroViking (Steve)]

Well done, Andrew. For a first effort, that's very good!

Cheers,
V