Mount strip & re-grease pros & Cons

[spaceboy]

Hi All

I am really stuck and I real need some veteran astronomers to help me out.

I have an EQ6 on a pillar in an obsy. I have aligned the polar scope to the best of my abilities. I have placed polaris in the centre of the crosshairs and rotated the mount until polaris has a very small elliptic path in the centre of the crosshairs. I'm guessing there will be more error in the etching of the hairs than there is PS to mount so I am fairly confident this is correct. I use http://myastroimages.com/Polar_FinderScope_by_Jason_Dale/ to then estimate where polaris should sit on the alignment circle. For visual the drift on planets is not a concern but imaging I have noticed there is growing star trails. So I checked the PA today and it is off by some way (see below). This is the second time this has happened in a short time of use. The last time I aligned the mount everything was done up uber tight to eliminate movement from the occasional knock.

Has anyone came across this in the past? I know sometimes the bubble on the mount can be to **** so is there a possibility the mount is not perfectly level. There is a slim possibility I have used the alignment software back to front but I thought the software allowed for reversed views ??

Forgive the crude graphic

[spaceboy]

Don't know if this will help any but this is where I originally aligned the mount to polaris. This was several months ago.

[nightfisher]

wish i could help, but this is my weak spot

[Freddie]

An EQ mount does not need to be level, so this is not your issue

[spaceboy]

Thanks Jules but by the lack of helpful advice it looks like it may be others weak spot also.

I haven't a clue why it is drifting. The mount is bolted down solid, the PS is calibrated to the mount, I don't see how an uneven mount could be the problem as when the mount is rotated polaris stays centre of the cross hairs ??? I just don't know what it could be. The only other thing is I'm putting in the wrong lat into the polar finder software but I have checked that against my satnav and google earth ??????

Looks like I will have to monitor the drift over several nights and hope I sort it that way.

[spaceboy]

An EQ mount does not need to be level, so this is not your issue

Beat me to it

[malc-c]

I'm guessing that you are using EQMod to control the scope as it's observatory based ?

The best way to get the PA as near as dammit spot on is to use the built-in PA tool. You start by placing the bubble at either 12 O'clock, 3 O'clock, 6 O'clock or 9 O'clock position when viewing through the polar finder, the idea being that you choose the one that closes to the position of Polaris as shown on the application. Then place Polaris dead centre under the cross-hair of the PS, and then either use just the alt or az bolts to place Polaris in the bubble. You then select the originating position (12,3,6,9 O'clock) and press the alignment button. The mount is rotated round to the exact HA position. Once it stops, you simply use the alt and az bolts to place Polaris in the bubble. However, due to precession you really need to place Polaris slightly off the centre of the circle as shown in the attached image

This should be an ideal start for visual work - but for imaging further drift alignment would be needed to get the mount precisely PA enough for long exposures.

[spaceboy]

Thanks Malcolm but I do not have a posh obsy like yours my friend. As you will see from the below pic mine was only built to stop the wind buffering the mount and the neighbours eye balling me while I stargazed and was never intended for anything more than a scope and a wrapped up me .

I have though come across mention that the reticules in PS are not considered that accurate as they are based on Polaris rotation around the NCP from 2000 and so most PS are 10 years out of date ??? This may explain the drift at the PS and my need to finally accept defeat and some how brave drift alignment. At best I can only make out stars 35-40' in the east so I don't know how that is going to work out. Anyone know of a full proof guide to drift aligning ??

[Steve 1962]

Have a look at this - it seems to work for me

Alignmaster von Matthias Garzarolli

I'll be interested to hear how you get on

Steve

[malc-c]

Hey your obsy is dead posh !

The epoch 2000 issue has been addressed by Chris in the latest version of EQmod, hence why you place polaris in the top half of the bubble as shown. I had mixed results with Alignmaster, but using the darv method with a dslr camera worked for me

[lukebl]

As your scope is permanently mounted, why don't you use drift alignment anyway to refine your alignment. I can't even see Polaris from my peir-mounted EQ6, so I use EQAlign which is brillant and free.

[spaceboy]

As your scope is permanently mounted, why don't you use drift alignment anyway to refine your alignment. I can't even see Polaris from my peir-mounted EQ6, so I use EQAlign which is brillant and free.

I cannot see any stars on the horizon. I was under the impression the lower the better. Besides I cannot find a written guide for dummies and nothing on utube to show how it is done.

Nothing comes up on the link you sent other than another link for installing firefox3 ??

[lukebl]

I cannot see any stars on the horizon. I was under the impression the lower the better. Besides I cannot find a written guide for dummies and nothing on utube to show how it is done.

You don't need stars on the horizon at all. The ones I use have a declination of around +10 to +30, and 20-30 degrees above the horizon.

Does this link work?

EQAlign Astronomical Suite

[spaceboy]

I cannot get the link to work Luke. I think it may be my firewall which will have to be modified for this site. What is the software ? Will I have to link it to the mount in anyway as I'm not that technically minded. Do you have a web link to an easy guide to drift alignment as I can't make heads or tails of it all.

[lukebl]

Odd that you can't link to it. Try a Google search.

Here's a screen grab of EQAlign, showing the area you have to select an Eastern star. Quite a range, which should be in reach for most observers.

[attach]83023[/attach]

[spaceboy]

Tried again and still no good. All I get is

[spaceboy]

EQAlign | Free Science & Engineering software downloads at SourceForge.net Is this it ???

[daz]

That is a problem with your browser SB.

The link works perfectly well.

The PS reticule will NEVER be perfectly accurate and is only designed to be 'close' to good alignment....

[daz]

EQAlign | Free Science & Engineering software downloads at SourceForge.net Is this it ???

Yes!

[themos]

My photographic method can tell you what your current polar alignment error is and produce a plot like this. If you want a plot like this, mount a camera on the scope, point it at NCP (near Polaris) and take two images at different RA positions of the mount (one with long edge of the sensor vertical and one with it horizontal). Send me the two images (say which one is which) and I will return you a plot like this one. Just make sure your focal length is such that Polaris and Lambda UMi are both in the frame in the two shots, a few degrees of FOV should do it.

[spaceboy]

OK downloaded from sourceforge just need some clear skies now. Thanks Daz for confirming the PS may be the weak link as I was beginning to think I had Gremlins. Thanks Luke for the info. I'm guessing the software is explains itself ??

[spaceboy]

My photographic method can tell you what your current polar alignment error is and produce a plot like this. If you want a plot like this, mount a camera on the scope, point it at NCP (near Polaris) and take two images at different RA positions of the mount (one with long edge of the sensor vertical and one with it horizontal). Send me the two images (say which one is which) and I will return you a plot like this one. Just make sure your focal length is such that Polaris and Lambda UMi are both in the frame in the two shots, a few degrees of FOV should do it.

Thanks Thermos Don't know how long it will be as the skies are clear during the day and no sooner it gets dark the cloud rolls in

[themos]

Just pm me when you're curious enough to try it.

[spaceboy]

Odd that you can't link to it. Try a Google search.

Here's a screen grab of EQAlign, showing the area you have to select an Eastern star. Quite a range, which should be in reach for most observers.

[ATTACH]82152[/ATTACH]

How do you bring up the simcam ? Told you I hadn't got a clue

[spaceboy]

My photographic method can tell you what your current polar alignment error is and produce a plot like this. If you want a plot like this, mount a camera on the scope, point it at NCP (near Polaris) and take two images at different RA positions of the mount (one with long edge of the sensor vertical and one with it horizontal). Send me the two images (say which one is which) and I will return you a plot like this one. Just make sure your focal length is such that Polaris and Lambda UMi are both in the frame in the two shots, a few degrees of FOV should do it.

Not sure if I understood correctly but here goes....

The one where I forgot to turn the obsy light off (orange glow along bottom) is the one with the mount pointing toward zenith in near enough park position (vertical ?) and the second is where the mount slewed to when polaris was chosen. (roughly where you would have the mount when balancing the scope.)( Horizontal ?)