Coordinates

[namreg]

Hi guys

Can someone confirm if this is correct please:

If, when I'm polar aligning, I set the movable scale on my EQ5 (at the top of the weight shaft) to the DEC of Polaris, which is apparently +89° 15′ 51″ (or as near as I can get it!), could I then point the scope in the general direction of an object with known coordinates, get the DEC right according to the scale, and then traverse RA only until I find it? If so, that would make my imaging life a whole lot easier!

Thanks

Doug

[namreg]

Can anyone help with this question?

Thanks

[brantuk]

Hi namreg - I find that most of the scales on these mounts will get you close to your object for observing but aren't sufficiently accurate for imaging. The best thing imho is to use a polar scope. It seems to work well in my CG-5 (Celestron equiv to EQ5).

Hope that helps

[namreg]

Hi Brantuk. Thanks, but I think you may have misunderstood. I do use a polar scope for polar alignment, which is fine and reasonably accurate. What I need confirmation of is, having polar aligned, if I then set the DEC scale on the mount to +89° 15′ 51″ (which is apparently the DEC of Polaris), will I then be able to point the scope in the general direction of an object with known coordinates, get the DEC right according to the scale, and then traverse RA only until I find it.

I'm not expecting this to put my target smack in the centre of my FOV, but if it saves my having to traverse both axes in this upside down/back to front world of astronomy, I'll be happy!

[brantuk]

Ahhh... yes I just re-read your original post and I missed the point a bit. My manual says that when the scope is polar aligned properly, Dec setting circle should read 90 degrees. So I guess it's conceeding a slight inaccuracy of 45 mins in the setting circle.

This could make the tracking a fair bit out when sighted on your object at certain magnifications. You may find the odd tweak is required in Dec between frames, and it will limit the length of exposure.

But it certainly will mean you only need to track in RA once on target, though you will have to move both axes to get on the object in the first place.

It allways amazes me how RA works after moving both axes - imaging will deffo be easier

[brantuk]

Of course - the software you use in post processing will position and align the frames - Deep Sky Stacker handles that nicely.

[namreg]

Yep, that makes sense brantuk. If correctly polar aligned, polaris won't be in the centre of your FOV anyway, but the celestial pole should be, so I should really set the DEC to 90. Bear in mind setting the DEC scale is just to find an object, not to track it - polar alignment takes care of that (up to a point!)

[brantuk]

Absolutely - hope I've helped and do let me know how you get on with it