9 replies to this topic

[Misterpm]

Hi I'm very new to astrophotography, I setup all my gear last night, polar aligned perfectly. But trying to do plate solving was impossible because no matter where I aimed the ota, the stars kept moving. Its probably a simple thing to rectify, but the life of me, I cannot
understand what caused it. My equipment
Skywatcher explorer 150pds
Zwo focuser
Zwoasi662mc camera
Ioptron ipolar
Sharpcap.
Skywatcher Eq5 mount I tried all different exposures, stara were nice and round.
Any help anyone can give me would be very gratefully received.

Edited by Misterpm, 19 March 2025 - 08:13 AM.

[belliott4488]

How long were your exposures? For plate solving, you need only a few seconds, just enough to capture stars. If you see movement in such a short exposure, something is definitely wrong.

 

Also - what is your mount?

Edited by belliott4488, 19 March 2025 - 06:29 AM.

[Tapio]

You list everything but the most relevant item regarding your question - the mount.

Before plate solving have you done star alignment, and checked that you have tracking on?

[kathyastro]

Was your mount tracking?  How confident are you that your polar alignment was good?

[Misterpm]

I've done star alignment in the past before coming across plate solving, which seemed easier. My polar alignment was spot on with a green circle and green cross in the middle.

[Misterpm]

I also tried the tracking in eqmod and in sharpcap. The stars even moved when the scope was parked, back to polaris.

[belliott4488]

Star alignment is a way to correct for tiny errors in your polar alignment. iPolar isn't perfect, so I generally follow my alignment from iPolar with a 3-star alignment just to be sure my mounts knows exactly where it's pointing. 

 

Plate solving is a way to confirm that your mount is pointing where it thinks it is, so that's kind of a third check. In that sense it makes star alignment unnecessary, although it doesn't update your mount's pointing model unless you tell it to do so.

 

Again:

1. What were your exposure times?

2. What mount are you using??

[revans]

Sometimes when a scope slews the mount can settle or slip off of the polar alignment that was done.  It can go off by enough to cause significant star movement especially at higher focal lengths.  When what you describe happens to me, I always go back and re-check the polar alignment.

 

Rick

[ChristianG]

The stars even moved when the scope was parked, back to polaris.

Hello.

 

Are you sure your mount is tracking properly?

 

Anyway, when the mount is parked, the motors are OFF, this means that tracking is OFF too. So of course stars will be moving. Even Polaris, as it is not exactly a the NCP.

 

Do I understand you correctly here?

 

--Christian
 

[Misterpm]

Hi Cristian, yes that's correct, I've been trying to plate solve which I can do so, but not able to solve and sync. When I've moved the scope tube, to another part of the sky, the stars keep moving, when it does that I try to plate solve again but still the stars are moving. I use a zwoasi662 mc camera which I've learned has a very small sensor, could that be the root of my problem? Thankyou.