Low pointing accuracy on a HEQ5 pro mount?

[daik]

Hello all,
I've got a new HEQ5 Pro mount and I've found it has really low pointing accuracy. It is to the point I a starting to think that perhaps there is something wrong with my mount.

When I was out last night I did a two star alignment. (Why not 3? I'll get to that). I started with Sirius and the mount whirred away and it pointed roughly at Sirius. I could clearly see it in the finderscope. So I manually make the adjustments to have it centred both in the finderscope and in the eyepiece.

I then selected Archenar as my second star and the mount whirs away and points just roughly at the right part of the sky! Achernar is not to be found in the finderscope even. I labour to find it and the mount goes "yep, ok" once I indicate I have Achernar centred.

If I go 3 star, it is the same operation again, just roughly the right part of the sky.

After that it can't find anything in the sky. I selected M42, but the mount failed to find it. Again it pointed at roughly the right part of the sky but M42 was not to be found. I selected Rigel, but again no bright star even in the finderscope. If I then select Sirius again it finds it and centres it, even in the eyepiece.

I have never had a GEM before, so I do not know if the above indicates that it is just poor (really poor?) alignment or if the mount is in fact faulty?

If someone could give me something I could try to determine if the mount needs repairs (it is under warranty) or if I need to spend more time on alignment that'd be excellent!

Any sort of help to indicate what I should be doing would be most appreciated. I always assumed it was my alignment but I've spent more and more time being more and more careful with my alignment but seen no improvement at all in the pointing accuracy.

So far a 3 start alignment gives me the worst and a 1 star alignment gives me, by far, the best pointing accuracy, which seems odd to me.

-daniel

[pfitzgerald]

I have the same mount as you Daniel.

Did you level your tripod and mount and align it North-South before you tried your alignment? It also be worth your while watching this tutorial and having a look at some of Dion's other tutorials - I've found them to be invaluable.

http://www.youtube.com/watch?v=4fO6hyYtPwM

Hope this helps.

Paul

[guggle]

This might sound like a dumb question, but when you were aligning to each star, were you using the direction buttons on the hand controller, or manually adjusting by releasing the clamps?

[Astroman]

Also make sure your Location is set correctly for the southern Hem, and your time. date. and DST settings are spot on otherwise the mount will think your in another part of the world. I only use the HC when testing, but primarily use EQMOD, but same rules apply, make sure you have all the settings right first, it could be that you didn't set it for the Southern Hem.

Let us know what you find.

[Barrykgerdes]

To get accurate gotos with a GEM you will need two accurate base dimensions first before you do your alignment. Accurate date/time/location and a correct polar alignment. (including mounting of the telescope to avoid cone error)

Doing a polar alignment with the polar scope is the method asked for but the the drift method is the best and can be very time consuming but it is best to use and practice will reduce the time taken

Normally the date/time/location will be required in the setup from the controller. In theory the alignment of three stars as per the instructions in the Synscan manual should be enough but it is assumed that your first action was to use the polarscope and hour angle to get the polar alignment close. If these dimensions are more than a few arc minutes off you will not get your gotos within the FOV of your eyepiece until corrections have been applied.

A lot of people recommend the EQMOD for alignment because before Synscan this was the only way. However unless you are familiar with EQMOD it is far better to use the Hand controller and avoid having to connect a computer to do your alignment.

Barry

[daik]

Thank you all for your replies. I will go out and tell my mount "it's not you, it is me". And then I will go through the setup again.

To answer specific questions:


Yes I did level it, I'm always careful with that. How accurate do I have to be? I use a spirit level and as long as the bubble is between the lines I've called it good, do I need to be even more careful?
I aligned the 'N' marked leg with true south as best I can determine it. I have an electronic compass that allows me to take magnetic declination into account (which I grab from http://magnetic-declination.com/ ) Achernar is pretty much straight south and as I can judge from where the leg is and Achernar is it seems pretty good. I've done a 30s exposure and it shows some drift of the stars, which indicates a slight misalignment.
When I adjusted I used the hand controller. You are right, always start with the simple solutions :) Occam's razor and all.
I have grabbed my location off the GPS on my phone (not using decimal, using degrees/minutes) which should be enough?
Date/time is set accurately, within a minute(probably even far better than that) of actual time I'd say.
I shall spend some time doing better polar alignments next time I am out. Would prefer to use the time observing rather than aligning, but hey, I suppose there are no shortcuts, at least not the first few times.

Again a big thank you to you all for your inputs, I shall attempt this some more, but now it feels like I can be certain it is user error rather than a problem with the mount. If I can get whatever object visible in the finderscope I call it a win. If I can see it in the eyepiece (40mm when I look for stuff) it is total victory.



-daniel

[Astroman]

If you setup in the same position everynight, spend a bit of time (a couple of hours of one night) to do an accurate polar alignment. Learn drift aligning, if you don't have the mount connected to a computer. Mark the position of the tripod legs on the ground, or put a line on the ground which matches the back legs of the tripod. Do this once and every night you go out, as long as you havent moved the AZ and Alt bolts on the mount you should be very close to polar aligned. Good luck hope you get there.

[chiaroscuro]

One other thing - increase the slewing speed to 6 or 7 when tracking to the alignment stars, otherwise the time taken at the default speed, allows significant error to occur. To do this, after selecting the aligning star, press 2, then 6 or 7, then enter.

[AstroDiggle]

Hi Daik....I'm new to all this....but I also have a new HEQ5 mount and am trying to improve my alignment. I can't see south from my backyard...so I'm estimating using compass and inclinometer. I think the other night was the closest I have come...although slewing to Jupiter after alignment...it wasn't in the FOV of the finderscope. Easy then to adjust when the subject is bright and easy to find.....not so good with dimmer things....but...I'm going to keep at it...hoping that practice makes perfect and that the problem at the moment is the "nut behind the wheel"

[widow18]

Just my two cents worth.
To find True south, use solar noon, methods available on the web. It is free and absolutely perfect if done correctly. A compass will probably never come anywhere near that accuracy .
Regards
Peter

[beyond]

I was having similar problems before I updated the hand controller firmware to V3.35. This firmware added a polar alignment option that works great. You need to do a two star (or three star) alignment then the Polar Align option appears. It will slew the mount away from your selected reference star then get you to adjust your Alt/Az bolts to re-centre. You only need 2 or 3 bright stars. I have not looked at polar scope since.

[Craige]

Last weekend I used Solar Noon to find true south after having accuracy issues with my HEQ5. That night I hit every target with my GOTO.

Craige