EQ6 3-star align problems

[Ben Ritchie]

Due to the clear but full moon/hazy/windy conditions last night I had an evening housekeeping in the observatory and getting a few things setup, and also spent a bit of time playing with the EQ6/pro. Previously i've only ever one-star aligned (same with my old HEQ5) which has been good enough for quick and easy goto. But I tried three-star aligning last night, but never got it to work....

Polar alignment is close, not perfect but close, and i'm pretty sure the settings in the handset are correct - lat/long, time, etc. Started in the correct position. The first slew (Deneb) wasn't great, but in the right ballpark, the second (Dubhe) significantly closer and the third (Vega) put the star right near the centre of the eyepiece at 130x power. So seemed to be working correctly. But every time I got "Alignment Failed". Tried with a different set of stars and got the same thing. I think the handset briefly shows "Calibrating" (?) before "Alignment Failed".

Any idea what could be going wrong? One- and two-star align both work fine (admittedly I don't think the first one can fail, it just accepts whatever you say?). Do I need to work with a cross-hair eyepiece to get the star precisely centred, rather than guessing in a high-ish power eyepiece?

Also, once you get "Alignment failed" what mode are you running in? Tracking has switched to sidereal (unlike the "off" mode when you start up and don't align), but goto appears weird - telling it to goto Vega (which was in the centre of the FOV) produced a ten-degree slew to somewhere random. Do I need to turn off, go back to home position and start all over?

And one other question, when doing PAE should there be any acknowledgement from the handset that the data is stored? After the "recenter" bit (or whatever it says, I forget) and press enter it just seems to go back to the menu, and it's unclear if it's done anything.

[Ben Ritchie]

One other question, when I park (which works ok) and power up, it comes up with the normal start sequence and - after a bit - asks if I want to start alignment.

At that point, do I say yes and 1-star align (hopefully keeping the previous 3-star align data I did before parking/powering off) or say no and turn tracking on manually (as the mount is not tracking until you've completed alignment)?

[MikeP]

Hi Ben,

The algorithm changes when three (or with EQMOD three or more) stars are used. Its just educated guesswork but I think the "alignment failed" occurs when your adjustments are "too great".

I've not used the handset since 2007 but never had an alignment failed once I got it working. Have a look at my suggestion here ... http://stargazerslounge.com/equipment-help/86457-synscan-align-problems.html#post1278041 for getting initialised.

Also, if you plan to use the GOTO after the three star align, make sure the triangle formed bounds the object. Ideally switch to EQMOD it is much easier than the handset.

Mike

[MikeP]

Hi Ben,

Just educated guesswork again but I think once you power down any coordinates are lost - all the mount remembers is the position of its encoders in what it assumes is the PARK position.

I'm afraid I can't remember how / when tracking gets turned on when using the handset.

Mike

[Ben Ritchie]

Thanks Mike, useful stuff in the link - I see i'm not alone!

I've avoided EQMOD thus far because i'm mostly visual (and my imaging is done at 230mm focal length, so undemanding!) - so all I really want is basic, reasonably-accurate GOTO that puts a target in the 13mm Ethos FOV and a park/power-up sequence that means I can roll off the roof and get going, rather than faff around with aligning each time. So if I can just use the handset and avoid bringing a computer into the observatory that would be a good thing.

[MikeP]

Ben,

I bought an EQ6 when I started out but didn't have a clue where the stars were that the handset listed, so I kept nipping indoors to look them up on my planetarium software, then back to the garden to see if I could see them, were they blocked out with trees, houses etc etc.

With EQMOD (for visual) I point the mount north using a compass or just by eye, the altitude is permanently set. Power on connect to my planetarium (SkyMap) and click on whatever I want to go to - usually a star near the DSO, centre it, synchronise then slew to my DSO, centre it, synchronise, enjoy the view then on to the next target, synchronising as I go. EQMOD keeps each mapping and the slewing gets more and more accurate.

Taking the laptop out is a pain but for me it is much easier than the handset. Also there is no need to input time / date / location.

Good luck.

Mike

[Ben Ritchie]

I bought an EQ6 when I started out but didn't have a clue where the stars were that the handset listed, so I kept nipping indoors to look them up on my planetarium software, then back to the garden to see if I could see them, were they blocked out with trees, houses etc etc.

Yeah, this is a pain - i've got fairly restricted visibility, placing the observatory was a case of compromises in my garden, and I don't have full-sky coverage so trying to remember if I can actually see Rasalgethi, Sadalsuud or Zubenelgenubi is annoying. And that's assuming I even know what they are, and don't just guess that the bright(er) star I can see is the right one

I probably will give up and EQMOD, just trying to see if I can do without at the moment. In general once i'm up and running things work pretty well, it's just the power-up routines that are a bit less than ideal at the moment.

[steppenwolf]

Hi Ben,

Assuming that your mount is 'permanently' installed in your observatory, here is a little trick that will make your future star alignments MUCH more accurate and repeatable:-

The EQ6 mount does not have digital optical encoders so it does not have any feedback system to determine where it is pointing so it is necessary to start the session with the telescope in a known position, the ‘Park’ position.

As you know, this Park position is with the weights pointing downwards and the telescope pointing upwards but this is a purely subjective position BUT the mount assumes it to be an absolute position and makes its first slew on the basis that the mount was accurately parked at the start.

Many mounts work on this basis and it is a reasonable method of controlling the mount but the accuracy of that first slew can be greatly improved by NOT making adjustments using the hand controller (or EQMod) controls. Instead, I issue the slew command and when the mount stops moving, I carefully unlock the clutches on the RA and DEC axes and manually push the mount around until the alignment star is in the centre of the field of view (ideally on a crosshair) and then I clamp the clutches to lock everything in place. At the end of the session when I issue the ‘Park’ command, the mount will park to exactly the correct position all ready for the next session.

This works very well indeed!

[Brinders]

I have heard of people having these problems with the EQ6 Pro before. When I had mine more often than not I got a successful 3 star alignment and that is with a restricted view too.

It helps if you do know the stars you are looking at of course, but I found that if the handset threw up one that I didn't know, or was hidden by trees or the house, I would simply scroll through the list until there was one I could identify with ease (Vega, Deneb, Mizar, Polaris etc trying to ensure that my three star were spread across the sky and not a straight line from one another).

This way GOTO was reasonably accurate (I found that after slewing to a few targets the object I wanted to view progressively appeared away from the centre of the eyepiece). I also used my TAL 25MM which has a cross hair reticule to place the alignment stars dead centre.

Finally, make sure you start the mount facing polaris with the counterweight bar and weights pointing straight down and the scope centered and looking up.

One other thing, I found on the occasions that alignment did fail it helped if you let the scope park itself then start again.

Hope that helps,

Brinders

[Reggie]

I had a couple of issues to start off with and I was given the advice that Steppenwolf has given, I can agree that it is a superb method.

The way I was told to do it (and to check) was to start the alignment, loosen the clutches one at a time and move your target into centre of the crosshair, then issue a park command, then start the alignment process again, choosing the same first alignment star to check that it is where it thinks it is Now continue with the rest of the alignment.

You'd have to use this method on eqmod as well.

I wonder if there would there be a way to retrofit HEQ5/6 mounts with a digital encoder and interface it with an eqmod dll?

[Ben Ritchie]

Thanks guys - is that a technique for getting 3-star align right from a fresh power-up, or does it need doing on resume from park as well? in the latter case that's a major pain in the backside, as it pretty much undoes all the benefits of park in the first place?

I don't mind the align process being a bit cumbersome from scratch, but for resume from park i'm really hoping that I can turn the mount on, hit goto and take it from there

[Reggie]

I use this regularly because I don't have a permanent setup. so once you're aligned ben you should be fine from a resume from park, as long as the mount hasn't moved at all in the meantime