pa alignment help

[chemtom24]

on my eq5 mount when i look through the polar scope i can get the 4 stars in the trepzium lined up, marked as 4 red dots.. but the 5th red dot in the middle of nowhere is the brightest star i can see, which im guessing is polaris, but its no where near the marker line. if i twist the scope round then i can get it on the marker but then the trapezium is out?

any ideas?

ps. when i align the trapezium i can get pretty good alignment with a dlsr with 50mm lens for ~30s +

[ScubaMike]

Correct me if I'm wrong someone, but the constellations in the polar finder are not meant to be used to line up with, just to give a representation as to which way round the RA axis should be spun so that the Polaris circle is in the correct place.

So if the plough is to the right, it should be to the right in the eyepiece (but not visible in the polarscope eyepiece).

The crosshairs are the Celestial pole, the small circle is where you place polaris (it may not be at the bottom when you have spun the RA to match constellation positions).

My EQ5 polarscope has a few constellations in it for ease of use, but I don't think I've actually seen them in the polarscope.

There is a more accurate way of positioning the RA Axis, but the above should give you a decent approximation.

[chemtom24]

thankyou mike , so its pure chance that i foudn 4 stars to line up with the trapezium? and the trapezium represents ursa major? and is the brihgt star polaris then?

[chemtom24]

that wooudl also explain why i have good enough PA for dslr+lens imaging but not dslr through a scope, because its roughly aligned (with polaris in the fov of the polar scope, but not dead on) bnext clear skies il have another bash.

thanks again mike

[ScubaMike]

My guess is that is is not Polaris, too close.

Maybe eUMi. - Then again, if the Polarscope is an inverted image, it wouldn't be (I'm confusing myself here!)

I'd look further afield for polaris, When I find it, it is the only bright star in the FOV of the polarscope.

[chemtom24]

My guess is that is is not Polaris, too close.

Maybe eUMi. - Then again, if the Polarscope is an inverted image, it wouldn't be (I'm confusing myself here!)

I'd look further afield for polaris, When I find it, it is the only bright star in the FOV of the polarscope.

the four lined up with the trap are very faint, and barely show up when i turn on the low power red led reticule. the 5th red dot is the only bright one.

[chemtom24]

i think its pure chance that ive found 4 stars that almost fit the trap shape lol who'd have thought

[ScubaMike]

Could be then.

I find PA a real pain, but I'm really impatient.

I have the same mount as you, and have used washers to mark the tripod feet positions. I don't adjust the tripod leveling or alt/az adjustment on the head.

Means I can accurately reposition my tripod and PA stays quite close, I couldn't tell the difference. Might be worth trying (really unobtrusive) - my wife complimented me on not messing up her patio.

Just got to see what the grandkids make of it, they'll probably have them up, despite them being epox'd to the flagstone!

[chemtom24]

Could be then.

I find PA a real pain, but I'm really impatient.

I have the same mount as you, and have used washers to mark the tripod feet positions. I don't adjust the tripod leveling or alt/az adjustment on the head.

Means I can accurately reposition my tripod and PA stays quite close, I couldn't tell the difference. Might be worth trying (really unobtrusive) - my wife complimented me on not messing up her patio.

Just got to see what the grandkids make of it, they'll probably have them up, despite them being epox'd to the flagstone!

hehe ive just been reading a thread about makring up the feet and someone had expoxy'd them to the patio. i have some epoxy, and i layed my mothers patio, so i think i may do the same! i layed the thign so she cant moan! but i can see it now.. lots of weashers glued down for various viewing positions to get around trees etc lol! once i get a good PA i think i will mark up, at least it gives me a decent starting point even if i have tio tweak each time.. will save a good 10-15 minutes, cos liek you (even tho ive been doing it wrong ) i find it a real PITA!!

[themos]

The four stars in that trapezium are for polar alignment in the Southern Hemisphere.

This is what you do in the Northern Hemi.

And this is what you do in the South

[chemtom24]

so themos, i put the trapezium in the direction of ursa major? and then use drift alignment to get accurate PA?

[themos]

No. Forget the trapezium!

You need to rotate in RA until the line running centre-to-edge is at the correct angle for your location+time+date and then adjust the elevation and azimuth of the mount to put Polaris in the little circle.

[chemtom24]

thankyou very much themos looks liek rain tonight but will giv eit a go first clear sky.

thanks again , much appreciated

tom

[themos]

Here's a quote from a Polar scope guide:

Polaris is not exactly on the North Celestial Pole, you need

to offset the telescope's R.A. axis from Polaris by a small amount

in the correct direction. There is a radial line in the Polarscope.

Along this line, there are tick marks and a circle. Rotate the mount

in R.A. until this line points towards Beta-Ursa Minoris (Fig.h-4). If

this star can not be seen, Mizar, the second star in the Big Dipper's

handle, can be used. If these stars can not be seen, point the line

in the pole finder away from the constellation Cassiopeia. i

Do you know how to find Beta of Ursa Minor also known as Kochab? It would help enormously. Say that you've spotted it in the sky, naked-eye, and it's at 4 o'clock from Polaris. Then turn the RA axis, looking through the polarscope until that radial line seems to reach towards 4 o'clock.

Then, lock the RA axis and adjust your mount's up/down (elevation) and right/left (azimuth) controls until Polaris sits in that small circle.

[chemtom24]

themos i do not, but i will have a good go at learning it.

thanks for the help, the other night i felt liek selling up i was that frustrated!!

[chemtom24]

just cdhecked stellarium it looks liek kechab will sit at about 10/11 o clock to polaris... is that right?

[chemtom24]

so i get polaris in the small circle and the radial line pointing towards kechab?

and youre talking abotu the ra /dec coptrols... im using a polar scope not the actual scope.. so its alt/az controls???

[themos]

Kochab seems to be at about 10 o'clock from Polaris at the moment.

To make that line point to Kochab, you will have to rotate the polarscope. That's the RA axis. To put Polaris in the little circle you'll have to move the alt/az controls of the mount.

[Rustysplit]

Chemtom24,

Do a search for Astrobabys polar alignment article. It is how I do mine on the same mount and it works a treat.