Ra tracking fine but Dec drops off

[AstroNebulee]

Hi

I have a skywatcher eq3-2 mount with my skymax 127 on it, I have installed a skywatcher single axis motor to the ra control, now when tracking (say Jupiter as that's the only one that was visible long enough tonight) the ra tracks gone but Jupiter drops out of the ep. Is this a polar alignment issue (as I thjnk I'm pretty much bang on) the latitude set wrong on the mount (I'm in North Cornwall 50.62 according to Co) my mount reads just after 50, the bubble is in the centre of the target on the mount or are the weights wrong on the mount (even though its balanced fine) not sure if I'm missing something. I'm sure it needs a bit of fine tuning somewhere. Bit of a silly question to ask. 

[michael8554]

Hi Lee

If you have Polar Aligned and it's "bang on", then your Lat setting must be correct.

But to get to the bottom of these issues you need to quantify your PA figure, "bang on" is meaningless.

You say that Jupiter "drops out of the eyepiece" - is that in RA or Dec  ?

A RA drift could be the Periodic Error in your mount.

A Dec drift could be the mount shifting due to loose mesh between the worm and wormwheel, offset balance slightly to take up that slack.

Michael

[AstroNebulee]

7 hours ago, michael8554 said:

Hi Lee

If you have Polar Aligned and it's "bang on", then your Lat setting must be correct.

But to get to the bottom of these issues you need to quantify your PA figure, "bang on" is meaningless.

You say that Jupiter "drops out of the eyepiece" - is that in RA or Dec  ?

A RA drift could be the Periodic Error in your mount.

A Dec drift could be the mount shifting due to loose mesh between the worm and wormwheel, offset balance slightly to take up that slack.

Michael

Hi Michael 

Thank you for your reply and suggestions, it's the Dec that drifts slightly, I'll try offsetting the balance on the mount to see if this cures it as the ra tracks fine. 

Kind regards 

 

Lee 

Edited August 14, 2020 by LeeHore7

[CraigT82]

Drifting in dec means your polar alignment is off, have you got a polar scope on the mount? 

[Cosmic Geoff]

I would not rely on the Latitude scale shown in the photo. The latitude scale on my EQ5 seems to be a degree or two off. You need to do a polar alignment.

[AstroNebulee]

4 hours ago, CraigT82 said:

Drifting in dec means your polar alignment is off, have you got a polar scope on the mount? 

I've no polar scope fitted to it but polar aligned it as per instructions, think I may have to get a polar scope for my mount and also polar align again when the next clear night is, which looking at Co is some time away 

[AstroNebulee]

3 hours ago, Cosmic Geoff said:

I would not rely on the Latitude scale shown in the photo. The latitude scale on my EQ5 seems to be a degree or two off. You need to do a polar alignment.

Thank you, I'll polar align it again when possible 

[Jiggy 67]

5 minutes ago, LeeHore7 said:

I've no polar scope fitted to it but polar aligned it as per instructions, think I may have to get a polar scope for my mount and also polar align again when the next clear night is, which looking at Co is some time away 

I’m not familiar with the instructions you refer to, does it just say point the mount North? If that’s the case, your PA will be miles out and as others have said, the altitude scale is rubbish, on my EQ6 R Pro, when PA is good, this scale is way off what my published latitude is. I’d say your issue is purely polar alignment. You would benefit massively from fitting a polar scope if the mount allows it

[AstroNebulee]

7 hours ago, Jiggy 67 said:

I’m not familiar with the instructions you refer to, does it just say point the mount North? If that’s the case, your PA will be miles out and as others have said, the altitude scale is rubbish, on my EQ6 R Pro, when PA is good, this scale is way off what my published latitude is. I’d say your issue is purely polar alignment. You would benefit massively from fitting a polar scope if the mount allows it

Hi Jiggy 

Basically yes they say to align to true north and set your latitude to your location, I will fine tune this now I know it's a polar alignment issue, so as you say the latitude scale is completely wrong, I will get a polar scope for my mount and seen one on FLO for £32, thanks so much for all your help, clear skies 

[Jiggy 67]

2 hours ago, LeeHore7 said:

Hi Jiggy 

Basically yes they say to align to true north and set your latitude to your location, I will fine tune this now I know it's a polar alignment issue, so as you say the latitude scale is completely wrong, I will get a polar scope for my mount and seen one on FLO for £32, thanks so much for all your help, clear skies 

I wouldn’t say that the altitude scale is “completely wrong “ just not accurate, it will get you in the ball park. If you imagine that the North Celestial Pole is an infinitely small dot in the sky, close ( in our comprehension) to Polaris then just using your eyes to get the mount RA axis anywhere near it just ain’t gonna happen. A polar scope will get you much closer, but then, if you want to do Astro photography you would want to be even closer!! Welcome to the world of tracking objects!!.....

[AstroNebulee]

4 minutes ago, Jiggy 67 said:

I wouldn’t say that the altitude scale is “completely wrong “ just not accurate, it will get you in the ball park. If you imagine that the North Celestial Pole is an infinitely small dot in the sky, close ( in our comprehension) to Polaris then just using your eyes to get the mount RA axis anywhere near it just ain’t gonna happen. A polar scope will get you much closer, but then, if you want to do Astro photography you would want to be even closer!! Welcome to the world of tracking objects!!.....

Forgive me Jiggy I meant not very accurate latitude scale, it definitely is a small target to aim at for tracking, not as easy as it looks this tracking lark is it, but as long as I can track a target sufficiently for now I'll be happy, I'm a total newbie and only seriously into astronomy since April this year, so forgive my naivety in some respects, but this hobby is fantastic a well worthwhile when you get some fantastic views and results, clear skies