SideOfPier issue ?

[TRAPPIST]

Hello Bob,

The SideOfPier property was in our understanding to distinguish between the both possible ways of tracking: instrumental declination < 90 and instrumental declination > 90. As this cannot be distinguished when looking at equatorial coordinates (where DEC is always < 90), the flag SideOfPier seemed to make sense.
Now, we saw in the conformance test program of ASCOM, that in fact the SideOfPier is ONLY related to the hour angle position. In that case, it seems to be totally redundant, as it
1) does no longer distinguish between the DEC > 90 / DEC < 90 cases and
2) can be reconstructed only from the hour angle value.
For our NTM-500 this is usually is not a big issue as it can track indeed one range of hour angles in pierEast and another in pierWest (as it cannot go over the Meridian). For our new NTM-1000 however, which is in our understanding still a GermanPolar mount, it does matter, at it can go way over the meridian, both for DEC < 90 and DEC > 90.

thank you !
Emmanuel

[Bob Denny]

Emmanuel - I am a bit confused. As usual, we need to talk about tracking versus slewing for a GEM. It is possible for many GEM to "go way over the meridian" while tracking but if slewed over the meridian, it will flip. In general, actually, "the meridian" can be any hour angle, and indeed there are mounts which implement some fancy flip points that are different depending on whether the slew is west to east or east to west.

I'm not sure what your question is. Are you having a problem with the NTM1000? Also I think it must be possible for the NTM500 to track east to west past the meridian. A GEM must never flip while tracking, right?

[TRAPPIST]

Hello Bob,

We are just not sure what ASCOM "expects" from us to do. People developing the NTM1000 mount circumvented that now so that it works somehow, but it is not clear for them if what they did, was done in the way it is meant to be.
Note that the NTM1000 is an EM that does not flip even if looking a bit like a GEM (the pilar is tilted).
My post above was relaying their concern about this pier side.

Cheers,
ej

[Bob Denny]

Re-reading your original post I am now even more confused. This mount cannot track across the meridian? I tried to get info but I can't find these mounts on the site:

Snap1.jpg

We will probably need to talk by phone.

[Colin Haig]

Bob, I think this is the mount the late Per Frejvall worked on the ASCOM drivers for.

[Bob Denny]

I think you're right, but I can't visualize what it is nor can I imagine what non-GEM would not be able to track past the meridian (unless I misunderstood Emmanuel). SOme of these tricky geometries can be modeled as simple equatorial but then there's a problem with the dome alignment because they have the geometry of a GEM sort of so what do you do etc? I'll wait to get info and go from there.

[Peter Hannah]

Sorry for jumping in while pursuing another thread, but the NM-500 and NM-1000 mounts seem to be made by ASTELCO (http://www.astelco.com/), not 10Micron. Per Frejvall wrote an ASCOM driver for 10Micron mounts, and the excellent ModelMaker utility which automates the process of making a mount model for accurate slewing and tracking. But I cannot find a link between ASTELCO and 10Micron.

Peter.

[Bob Denny]

Oh you are right!!! Sorry everyone. I was confused.

[Colin Haig]

I was confused too. Sorry about that.