Drifting

[wookie1965]

I have had my EQ5 out a couple of times now twice I have had caution previous NPE applied not a clue what this is, but i have set up as per instructed leveled the mount,Polar aligned added weights and ota checked polar alignment, I am having problems the other night went out M13,M92 bang in middle NGC6210 middle M16 not sure It was early may have been too light but next two M10,M12 were over to the right of eyepiece, last was M57 and it was nowhere swapped eyepiece to 25mm and no sign of the ring, can anyone give me an idea as to what I`m doing wrong please. The picture is how I aligned Polaris.

[Louis D]

What you're describing has more to do with slewing accuracy than polar alignment accuracy.  Once you have your object centered, does it drift out of the center over time or does it stay put?  If it stays put, your polar alignment and your tracking rate are spot on.  If the object drifts out of the center, one of the two is off.  Slewing accuracy determines if an objects lands in the eyepiece or not when you "goto" it.  That can depend on having your date, time, and location entered correctlly.  It can also depend on the accuracy of a two star alignment with subsequent object realignments as you recenter each.  There are also the issues of the orthogonality of the mount, the number of tics in the encoders, the accuracy of the stepper motors if encoders are not used, etc.  The further between objects, the less likely they'll be centered after a slew.

[baggywrinkle]

I have a similar polar scope on my EQ6, but I do not bother rotating it to get the ring over the pole star, rather I use a free app Polar Align by George Varros which tells me the position of the Pole star  and I simply align the mount use the RA & DEC bolts to that, check that it hold true once I have tightened up the bolts. I also do it with the OTA in place so the mount is fully loaded.

Have you ensure that your polar scope of correctly aligned? There are three small hexagonal headed setting screws to do this and the routine is described in the handbook. If it is not true to the axis of the EQ mount then you can tracking errors.

[Owmuchonomy]

What you are describing is GoTo error which is more about accurately mapping your local night sky.  Polar alignment is about aligning you mount's axis with that of the Earth. They are different matters to attend to.  If your GoTo is proving inaccurate then it is likely that an error in one or more of the parameters you entered has occurred.  perhaps you could advise us what GoTo system you are using and what parameters you have entered so far. We then may be able to help with the issue more appropriately.

[wookie1965]

Hi it is an EQ5 pro goto and I use syscanit to gather the relevant information. When I said drift it was not meant to be literal, I meant that the first few objects are dead centre then as i move to other objects they are over to the right and then not even in the FOV. The only thing that is out is Polar time and hour angle for some reason the figures on the handset do not match syscanit they are usually 2 out on each, Just a quick question do i change the mount angle to the elevation on the scyscan app or just the handset.