GOTO pointing nowhere near object!

[bujin]

Ok, apologies if the topic title is a bit cryptic - I couldn't think of a more descriptive one!

I went out for an imaging session a few nights ago.  I roughly aligned the mount towards Polaris, then tried an alignment.  Now, this is something I've noticed over a couple of months, but it was only the last session where I tried my first use of Alignmaster that it really started to annoy me and lead me to seek some advice!

When I select a star to align, the telescope slews, but ends up maybe 10-15 degrees off where it should be pointing.

I've ensured that the time is correct, that I'm in the correct time zone and not using Daylight Saving.  The date is correct, and the location is still set at the same as it always has been.

As I say, in previous sessions, I've done the 2 star alignment and made the massive corrections to the position, then done a couple of calibration stars, and after that, it works fine.  However, as I found to much frustration a few nights ago, Alignmaster won't correct if the error is more than 10 degrees out.

Anyone got any advice for me?    Is my mount knackered? 

It's a Celestron CG-5 GT mount, btw.

[Owmuchonomy]

Could be any of the things you mention. Are you sure your location is spot on and you are inputting Longitude West of the meridian? Once your mount is aligned with Polaris are you then aligning your scope with Polaris too. Are you sure it's Polaris. Keep at it you will get there.

[bujin]

Could be any of the things you mention. Are you sure your location is spot on and you are inputting Longitude West of the meridian? Once your mount is aligned with Polaris are you then aligning your scope with Polaris too. Are you sure it's Polaris. Keep at it you will get there.

Yeah, I initially thought that the location had reset itself, but I checked it and it's definitely set correctly.

I'm 100% certain that the mount was aligned with Polaris, and about 99% sure that the camera was aligned with Polaris too (I wasn't using the scope, just the camera attached to the mount).

[michael8554]

10-15 degree error sounds like a GMT/BST error in your setup.

Michael

[ronin]

Check what the start position of the mount should be. A mount/scope cannot slew to a star to align on accurately, unless the system presumes some starting position.

Also write down all the data from the handset, do not look at and think Yes it is right, just read what is displayed and write it down and then check it. From testing things it is amazing how people "see" what they expect to see. Not deliberately but the times I have found this is not exactly rare.

Make sure the timezone is actually correct. I have read of people setting this off by 1 so they do not have to say Yes to DST (why that is a problem I have no idea) trouble is that when DST is actually Off the scope can never be set to compensate so is 1 zone out. But as mentioned previouysly 15 degrees sounds like DST or Timezone.

[astrofox]

15 degrees sounds like an error of 1 hour in setup

[garryblueboy]

Polar alignment roughly doesn't always work I found that out on my HEQ 5 synscan would be miles out .

[bujin]

Thanks for all your responses.  I'll triple check the data next time I set up.  One of the first things I considered was that I had either the time zone wrong, or that it was using BST instead of GMT, as it did seem as if it was about an hour off the expected position.  The handset tells me that I'm definitely in the right time zone, using the right time (i.e. GMT at the moment) and that my location is pretty close (I'm selecting Liverpool as a city rather than inputting the exact coordinates, but Liverpool is almost exactly due north of my location, so shouldn't result in that big a difference).

But I'll definitely make a note of the handset settings next time I get a chance to set up just to confirm it all.

[Northern Soul man]

Hi Ya Bujin, I had a problem a while back, not using any software to align - just visual, the mount was around the same amount out on the first alignment star - turned off then turned on again - same again first alignment was off - wonder if you have tried a factory reset yet - I done this and has worked  well since - after the first calibration star, the alignment was spot on for the rest of the alignment stars - I had a problem though last week, I sent the scope on a GOTO and the actual tube assembly was pointing the wrong way - 180 degrees out, the tube was pointing roughly at the correct position in the sky but the corrector on the Mak was facing the floor - very strange - might be worth a factory Reset  -unless you've already tried that - these mounts are great when they are working, but tend to throw a few "wobblies" every now and then.

Paul.

[ronin]

At least Liverpool is very likely the one you want.

Someone lived closer to Birmingham and used that, minor problem was they selected the first Birmingham and that was Birmingham Alabama. :grin:

[pete910]

For the celstron goto's I've found that putting your actual coordinates in help a lot. Also when aligning make sure the last movements are done with the up and right direction keys.

[Browny]

This is an interesting subject. My niece has a similar problem and being new to this I couldn't really advise her other that to check the co-ords she was putting in. Thanks guys I now have some more suggestions for her to try.