EQ mount with no meridian flip

[Astrofriend]

Now when I have started to use my observatory I face a new problem, meridian flip. Earlier at my balcony I didn't have any problem because I only had a free view to East.

Can that problem be solved and still have a German equtorial mount? After have googled on it I found some people who have solved it, not exactly how I want it but close.

I have collected my information on my homepage and a first simple drawing how I think will be a good solution for me who live at latitude 59 degrees:
http://astrofriend.eu/astronomy/projects/project-eq-mount-with-no-meridian-flip/project-eq-mount-with-no-meridian-flip.html

I'm a bit angry at myself that I didn't think about this before I built the pier and observatory, it had been much easier if I had been built it alreday from the beginning.

Tell me if you have done any attempt to solve this, maybe better ideas then my own.

/Lars

[AKB]

If you have money to throw at the problem you could consider going with either of the following Avalon mounts:

http://www.avalon-instruments.com/products/m-zero-equatorial-azimuthal-mount

http://www.avalon-instruments.com/products/m-uno-equatorial-mount

If you're more into DIY, it may, nonetheless, give you some ideas.

 

[The Admiral]

Having looked at the Avalon mounts I'm not at all sure that long OTAs can get away without a meridian flip. Very much geometry specific here I think, and a pier would help I guess.

Also pricey is the TTS-160 Panther, not a GEM but an Alt-Az with 'scope rotator.

I think I read somewhere that the even pricier 10Micron can go some way beyond the meridian before needing to flip, but I don't know how.

Ian

[Astrofriend]

Hi,

Yes they are great mounts, but this have to be a low cost solution. After googled around and with your links I see that I must reuse my EQ6 mount and rebuilt it. But no hurry to solve it, I can use it as it is until I found a solution I like and can manage to do.

I'm lucky to live at high latitude and don't have to tilt the arm very much.

Thanks for the help!

/Lars

[pete_l]

Or one of these: https://www.teleskop-express.de/shop/product_info.php/info/p8589_Lacerta-Bended-Knee-Pier-with-polar-fine-adjustment-for-EQ6.html

[IanL]

Why is doing a meridian flip such a problem? Reading your notes, you seem mainly concerned about astrophotography and guiding.

Using a combination of Sequence Generator Pro and PHD2 with an NEQ6 I have no problem with automatic (unattended) meridian flips:

- You can define when to trigger the flip, i.e. within x distance of the meridian.

- SGPro coordinates all the software, so does it between exposures, and uses Platesolve 2 to accurately re-centre the target after the flip.

- It also stops and re-starts guiding automatically, including reversal of any necessary calibration parameters in PHD2.

I've yet to have a flip fail on me - obviously you need to set up the cabling so that it doesn't snag, but it only took a few tests to satisfy me there was no chance of the cable snagging.

Yes the post-meridian images will be inverted, but again that really isn't an issue as pretty much any stacking software will know how to flip them around so that the entire set is properly registered.

There are only two real issues:

- You are not there to adjust the counterweights to keep the mount East-side heavy. Personally I don't have any problems in this regard as the mount (belt-modded) seems to track just fine regardless of which side is heavier.

- You're always going to get some fairly poor guiding very close the meridian with this type of mount due to backlash in the RA geartrain (as at some point it has to 'fall' from one side to the other and during that process it tends to see-saw between sides for a few minutes until the weight decisively shifts to the other side of the pier). Thing is, that's even more true if you try to image through the meridian rather than doing a flip.

[Gina]

That second Avalon works the same way as a fork mount which also doesn't need a meridian flip.  I have a project on the books for a DIY fork mount for a widefield rig but it's shelved for the time being and doubtful whether I shall get round to finishing it but who knows

[The Admiral]

2 hours ago, Gina said:

That second Avalon works the same way as a fork mount which also doesn't need a meridian flip.  I have a project on the books for a DIY fork mount for a widefield rig but it's shelved for the time being and doubtful whether I shall get round to finishing it but who knows

My understanding Gina is that both the M-ZERO and M-UNO act like fork mounts with half the fork missing! Unlike a fork, though, the length of the OTA that can be accommodated isn't limited by the 'cleft' of the fork, but if it is too long then the OTA can still collide with the mount/tripod, and that will then require a flip. I think I am right in saying though that even then it should be OK for southerly migrations across the meridian except at high altitudes.

Ian

[Astrofriend]

There are more then just the cameras get upside down. If I want to ad a second telescope in future I can't have it on the other side of DEC axis. It will collide with the pier or mount.

 

The Lacerta arm works, but that big one I can't fit in my observatory. Must have it compact!

The Avalon is a master piece, but 4000 Euro?

I added more drawings about my idea to solve this:

http://astrofriend.eu/astronomy/projects/project-eq-mount-with-no-meridian-flip/project-eq-mount-with-no-meridian-flip.html

 

/Lars