26 replies to this topic

[WadeH237]

Have you tried the C14 much just to see how it handles? I assume the not-fixed mirror is a hurdle in this case? 

I don't generally image with the C14.  Even with a reducer, I am way over sampled, and the FOV smaller than I like.

 

I do know from imaging with it in the past, that the mirror movement would absolutely prevent unguided imaging.  I did make a try at unguided imaging with my 8" EdgeHD, and found that even with the mirror "locked", I could only go up to about 2 minutes before I was unhappy with the stars.  It always requires an OAG for long exposures.

 

My unguided success has been with refractors.  I use Stellarvue 80MM triplet for wide field work, and an AP130GTX to get the 0.9 arc second image scale, which is about all that my site's seeing typically supports.

[Sacred Heart]

This is a hypothetical question to try to understand the theory. Lets say theoretically you had a completely stable mount on solid ground that is not affected by ground erosion or atmospheric conditions. And lets say the mount is perfectly accurate and never drifts.

 

And lets say you did a perfect polar alignment on the celestial pole to a 0.000" precision.

 

How long would this alignment last? I know about precession and the J epochs so I assume that means the coordinate system is constantly changing. Or does that only affect the location of objects and not the coordinate system itself. If so would that mean an alignment would last essentially forever?

 

And a bonus question: What about the average continental drift of 1.5cm per year. How long would it take for that to have an affect if any?

Okay, I am late to the party, but here goes.

 

Speaking for me only,  24 year old Paramount ME MKS3000 mount, I just i a polar alignment on my mount last week. I went from top bottom to side by side with different refractors.  I am portable, set up / tear down every time.  My last polar alignment before last week was done in April of 2022.  Sky X showed me that, I was surprised.

 

Now, technically, I lose my polar alignment as soon as I move the scope. This is true. However using a 550mm or 1000mm scope and being able to put it awfully close to where it was the night before the scope points correctly.  I do start out with homing, then slew to any star, it will be off center but on the screen, I will center the star, synchronize the Sky X map to the telescope and I am done.  Some may go to somewhere in the sky and plate solve and center, basically the same thing.  When I polar align, I use Sharpcap to do initial alignment, then do an all sky pointing model, automated mapping run. This is my pointing model and verifies my polar alignment.  Usually no adjustment is required.

 

Look at photo, see where the pier feet are. There is two aluminum blocks screwed to the concrete, one North and one West.  East is a freebie. Rat cage ensures level mount.

 

No scientific data here, just real world things I do.

 

Joe

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