HEQ5 Pro alignment fails : I must be doing something wrong...but I can't think what

[pauldaviesuk]

Hi,

I've had an HEQ5 mount (which I've upgraded to GoTo) for some time, which has had relatively little use for one reason or another.

I'm now in the process of rectifying that by build in an observatory in my back garden. I've the mount on a concrete pier (under a dome) and have roughly polar aligned it. Its not perfect yet, but will be fine for visual observing - I can see Polaris in the polar axis 'scope, and it rotates round the X-hair as I rotate the mount.

As it stands - so far,so good. I can use it quite well to star hop about etc. So the next stage is to get the mount to GoTo etc. This is where my problems start.

Let me explain my workflow @ the scope this evening (before the clouds rolled in again):

1) Set the mount+OTA in the home position - weight down & eyepiece down with the clamps finger tight.

2) Power up the mount (good battery) and accept the firmware version (v3.10) and warning messages.

3) Entered the location as 000.04W 51:39N & timezone +0 (ie London)

4) Entered the date as 11/17/2009

5) Entered the time as 20:00:00

6) Selected no DST

7) Selected '1' to begin alignment, and chose '3 Star Alignment'

So far, so good (I think). I'm standing there looking north, with the 'scope's eyepiece in front of me. The Synscan unit has selected the 1st aligment star to be Vega, which I can see fairly low down and to my left. I hit enter and watch the mount move the 'scope to point almost to the Zenith - actually, its looking slightly east...hmmm...not good.

If I undo the clutches and manually point at Vega, then do them up and use the hand-box to fine-tune the pointing, then continue, the alignment goes well.

If I leave the mount alone and use the hand-box to fix the initial failure to find Vega, then it gets the other 2 stars completely wrong too.

If I accept all 3 start positions, without manual correction, they are all wrong, but correct relative to each other.

It just always gets the initial attempt to find the 1st star miles off. I'm sure there must be something simple/obvious I'm missing.

TIA

Paul

[alfi]

hi

im not sure, but should it maybe be 004.??W ?

also your firmware is old, would not harm to update it.

alfi

[barkis]

Is the date entered as the US Format.? Although I don't think it would be accepted if the month was 17 .

Vega is circumpolar, so at 8:00pm it would be lowish in the south west at 8:00pm.

Ron.

[pauldaviesuk]

Thanks for your input..

Alfi.. its definitely 000.04W....as in 0deg 4mins. I'm only a few miles from the Greenwich Meridian. Wouldn't 004.??W be 4 deg West?...somewhere in Cornwall?

That said, the difference between 0d:4m and 4d:?m is not as much...compared to the pointing error I'm getting.

And yes I'll be looking into upgrading the hand-box firmware.

Ron..the date is in the format mm/dd/yyyy as specified by the hand controler...and indeed Vega is in the west at 8pm...which is why I'm not happy that my mount is looking for it somewhere near the zenith!

cheers

Paul

[Mikea]

Before you power down, do you use the "Park" position?

[NickH]

3.25 firmware

Try a 2 star align, try Vega and Deneb

Ensure you're balanced on all axis.

Get a decent 12V PSU as well

See how that goes

[barkis]

When alignment stars are selected for you, and for example Vega the first one selected is out of view in the E/P, should you not be using the controller to centre it, then press enter to slew to star number two, and centre that via the controller too. Enter again.

The electronics sense the steps required to correct the position of Vega, and also for the second alignment star. If you manually move the scope, it can't possibly know where it is pointing surely.

The motor initially counts the steps to the target, and again when you correct the wrong position. Again for star No. 2.

It should then be aware of where in the sky it is, and proceed fairly accurately from then on.

Ron.

[Astro_Baby]

Super double check your Lat Lon coordinates. I had similar troubles on first use and was entering a digit wrong.

I find the firts star is often out by anywhere up to 10-20' but when the mount is steered to it under power its fine with the other two.

Also if you do three star the mount can be super fussy about the actual positions which is why I use the finder to get the stars bang on the crosshair (and obviously have the finder well aligned to the main optics as well).

Check it after a reload of software and see what happens.

[tooth_dr]

What barkis says, you need to use the controller to centre the star, as this is how the computer works out how much to correct the alignment error. Otherwise the mount just assumes it is pointing to the right place without adjustment each time.

[pauldaviesuk]

Thanks again for your replies...

I'll be updating the firmware in the hand-box as soon as I can find the the cable, and a PC with a serial port (remember those!!), though I can't beleive v3.10 has such a bug as this!!

Barkis: I tried using the hand-box to move the 'scope on to Vega...this resulted in the mount gettig the locations of the other 2 stars competely wrong. (Moving the OTA manually, resulted in the mount successfully finding the other 2 correctly).

Astro_Baby: I'm not talking 10-20' here.. more like about 6hrs in RA and a few degrees in Dec.

NickH..I've also tried the 2-Star align.. Vega and Deneb.. again it get Vega completely wrong. Its well balanced and power is from a new, freshly charged 12v car PSU - the kind with a 12v socket, a 240v socket and jumper cables

I've been trying to get this woking now for a few weeks now..whenever the sky is clear enough to pick out the alignment stars, re-entering and re-checking all the location/time params.. I'm confident I've got them correct.

Well...looks like it's going to be overcast for the rest of the week....plenty of time to get the handbox updated...I'll report back any progress.

cheers

Paul

[arad85]

I'd be looking at the lat and long you are entering. Are you sure you're not putting lat in as long and vice versa (i.e. effectively saying you're at 51W, 0N)

[Merlin66]

I think the mount is not remembering the PARK position correctly.

After power up re-PARK the scope using the Utility menu and see if it still stays pointing to Polaris....

Also after doing the 2-3 point alignment ( using the clutch if need be) set the Scope to PARK and ensure it's correct.

At the end of the observig session use the Utility option to PARK the mount.

[SteveP]

Paul

Your workflow looks perfect as you describe on the basis that the scope is pointing roughly towards the NCP. This doesn't sound like a small error in your long/lat to me nor a problem with your power source if you are replicating the problem. My guess is that it is either an incorrect 'date' issue (but you seem to have checked and discounted that) or more likely it's connected to the mount's starting position, ie the 'park' position.

When you have had a successful 3 star alignment by manually repositioning the scope, slackening the clutches etc, on the 1st star have you then parked the position using the handset? If so, where does the scope park itself? In the normal CWD position or offset to some significant amount? If it's the latter, then that is a very strong indication that the mount is confused about its starting position.

If you haven't done this already, please give it a go. If the scope does park itself in an unusual position, start from this position and do a 3 star alignment. What happens then with the 1st star?

Steve

[SpookyKatt]

Are you not meant to be setting DST to yes ?

Kathleen

[RobertCL]

I too have had an "enjoyable" time trying to get the HEQ5 Pro goto to work well.

6 hours out sounds like you are not starting from the right place. When you first turn the mount on, the weights should be down and pointing in the same direction as the North leg and looking through the eyepiece of your scope you should be able to see polaris (actually the NCP, but you get the idea).

Then go from there with the procedure you are following.

A lot of people have said you must always use the hand controller to centre the star - this isn't quite true. You can centre the _first_ star (and only the first) by loosening the clutches and manually moving the scope. After that you must use the hand controller for the 2nd and 3rd stars. I take this approach all the time and seem to better results.

My experience has also shown that it's important to get the scope level and to be roughly polar aligned before starting the GOTO alignment. If it is off in polar alignment I find it misses everything by a little way, even after GOTO alignment, which is quite irritating.

Robert.

[pauldaviesuk]

Steve.. u r correct. If I Park the scope after getting an alignment success (by manually moving the scope to the 1st star), then the Park position of way off. I've tried leaving it in this odd position and powering the mount down, then manually moving it to the correct Parked position, before powering up again and re-aligning...it still goes to the wrong location for star 1. Next time I can actually see the alignment stars, I'll try out your suggestion.

SpookyKatt...sure DST = BST, which finished a week or 2 back.. we are now in 'Normal' time, so shouldn't DST be set to 'No' ?

RobertCL... you are correct... If I manually move the scope to correct the major position error on the 1st star, then the other 2 are very close. The problem is with the mount being so far out on the 1st star. And yes, I understand the need for accurate physical, polar alignent, but I don't think the initial pointing error is due to it being slightly off the NCP.

so....2 things occour to me.

1) to eliminate any manual data entry issues...how about using a GPS? I know Sky Watcher do a GPS Mouse kit @ about a £100, but I have an old TomTom GPS mouse..anyone know if this would be adaptable to the SynScan?

2) Is it possible that the mounts confuaion over its Parked location could stem from when I upgraded the mount to GoTo? This involved the replacement of the motors/encoders etc. Ofc, if the mounts just counts motor steps from the user set 'Parked' location this would not be the case.

Paul

[SteveP]

Paul

A bit of progress then! Your scope is so far out though that a more accurate GPS fix or having the wrong DST setting or it not being level or minor errors in your polar alignment will be unlikely to account for it being 6hrs and umpteen degrees out.

Next step which will should confirm the underlying issue... Go through your alignment process again and allow the scope to park itself in the 'unusual' position. Now without moving the scope, restart it (from this unusual position) and re-do a 3 star alignment. Do you find that the alignment gets closer to your alignments stars? If it does, then that confirms that the underlying issue is the Park parameters. Somehow, and it may be connected to when the GoTo motors were installed, the mount has the wrong 'park' parameters, ie it thinks it is starting from a position other than the CWD position. Have you used the scope since the new motors were installed?

Does the HEQ5 GoTo software allow you to re-define the Park parameters?

Steve

[pauldaviesuk]

SteveP...

point 1.. I agree, but a GPS might eliminate any possible typo issues in the future.

point 2...I haven't had a successful alignment since the upgrade.. I'm increasingly starting to think it may be the root of the problem. waiting for a clear sky to try some more ideas out, though.

point 3..I don't think so

cheers

Paul

[Merlin66]

When you do your first alignment star is the error in RA or Dec or both??

The 3.12 upgrade mentions the ADDITION of the Park options ie

Current position - park scope at current position

Custom position - slew and park the scope to the previously saved position

To save a parking position, choose one of the above parking postions under Utility-Park scope, then turn of the power.

If there is a parking position stored in the system, Synscan will prompt "Start from park position?" at power up.

Do you see this message?? Maybe your V3.11 definately needs to be upgraded!

[pauldaviesuk]

hmm.. you know i've just had a thought.....I wonder if, while installing the GoTo kit, I crossed the cables for the RA and Dec motors.....?

Thinking about how the scope behaves atm, I'm not that confident this is the solution....but after reviewing the installation notes for the GoTo upgrade, its about the only thing that could have happened.

If so.. its an easy fix, and I can check it out without opening the dome..so its weather independent!

cheers

Paul

[SteveP]

hmm.. you know i've just had a thought.....I wonder if, while installing the GoTo kit, I crossed the cables for the RA and Dec motors.....?

That's a possibility .. and I suspect you wouldn't be the first to get the motors mixed up!

It could be something as simple as that.

[pauldaviesuk]

so....I've looked into the guts of my mount and all is connected correctly....so scratch that idea... And I've updated the hand-box to v3.25... I guess I just sit tight and in anticipation of a clear night. Now...where did I put that G'n'T...while I wait.... cheers Paul

[alfi]

hi

is it possible to operate the mount with a scope with the dome closed?

you could check the directions of the stars you choose to align against, in stellarium or something like that.

it would tell you if trying out different park positions and procedures work, roughly, without having to wait for good weather.

alfi

[brendant]

I have seen a similar problem on my HEQ5 Pro in the past but the easiest way of avoiding the error is when you power up the handset before you do your alignment - drive the mount to the PARK position (PARK to home position not the current position), then realign RA & DEC to their normal startup positions if they are not already there then proceed to do your alignment and it will be correct.

It appears that the mount gets confused about where park is (starting point) and this is the easiest way of clearing the error as the mount then knows where it is starting the alignment from.

Brendan

[Merlin66]

I'm not sure that was an option under the original V3.11 firmware. With the upgrade to V3.25 it'll be interesting to see if the problem is solved.