Polar alignment using polar scope HEQ5Pro

[RobF]

Ok, so I've done the deed and upgraded seriously to a Skywatcher 8" Newt on a HEQ5Pro. Yay - its like XMAS. :)

Have been researching all the suggestions/options for polar alignment. I decided to try and have a go at polar scope alignment. To my amazement I eventually tracked down the octans groups and have succeeded in getting them aligned against the reticule for 2 nights now.


So, my question is - if the mount is level and I've got octans aligned, that should mean I now have the correct latitude setting etc? I've done this by twiddling and tweaking mount and RA by trial and error, but not used any circles on the mount or scope.


I had always thought how easy those northern hemisphere types have it, but have only now understood they need to have polaris transit times etc. Presumeably because you're aligning on a group of stars, rather than just one, you don't need to worry about adjusting the scope setting circles etc?

Should also mention I've spent a bit of time tweaking alignment of the polar scope first.


And many thanks to Davewaldo here for my first serious eyepiece (Hyperion) and the free 3 hour viewing session to go with it to convince me I was doing the right thing getting back into Astronomy!!
:thumbsup:


Rob

[Fox]

Correct, provided you have the mount level and your polar alignment scope aligned with the RA axis, the latitude is ok by default. Fox

[Fox]

ps it also means next set up will be easier, when the mount is level, you only need to adjust the azimuth since latitude is already set. Fox

[RobF]

Great - I've set it up from scratch and leveled a couple of times and got the same latitude, so at least that's one variable down.

Mounts a couple of degrees out, which isn't unusual I gather.

[davewaldo]

hi rob, sounds like your having fun. I've never had much luck with my polar scope. Maybe you can teach me once you have it worked out. ;)
I've just come in from a great night of visual observing. I just plonked my scope down quite roughly aligned south. It was wonderfully accurate putting all objects inside my 14mm EP. Pitty the moon was so bright. :)

[RobF]

I don't think polar scope aligning is ever going to take over from nebula spotting at star parties David! Too hard on the knees :P

Actually for all the effort, I don't think I've got any better alignment in the end than your getting with the "plonk technique". Must be picking dodgey stars......

[Starkler]

Did you ever actually take the time to ensure that the polar scope is accurately aligned to the axis of the mount?

There are 3 hex grub screws near the viewing end of the polar scope to adjust this. When I got my mount new this was some way out.

Procedure:
Remove weights and get the polar scope aiming at a distant object such as the top of a power pole.

Rotate on the RA axis and watch that the reticule cross hair centre doesn't shift as you do so.

Adjust hex grub screws to centre the cross hairs to the axis of rotation. Loosen one, and firm up the other two to shift it in the desired direction. Its quite a fiddly operation but you should only have to do this once.

[RobF]

Thanks Geoff - yes I did spend quite a while with the scope pointing out a window at a distant light on a building. Not perfect, but no more than 1-2 times width of crosshairs movement when scope rotated.

Was aiming just over the neighbours' house over the road the whole time to target the distant light - probably would have looked a bit suss if they'd noticed my late night efforts!..... :P

[dazastar]

I successfully used the suns shadow to polar align my scope. firstly, if you ask the sydney observatory very nicely on observatory@phm.gov.au. They can provide you with the times for a couple of days when the sun hits the north position. eg, July 29 at 11.46am the sun was perfectly north. You then hold a string or a pole at the top so it swings freely, and use the shadow cast over the body of your eq mount making sure it lines up. I was able to get my scope (at the above date) to align so well, the the object at night stayed in the field of view for hours.

[AlexN]

From my back yard, Octans is a no-show, however when at astrofest up at Duckadang, I basically plonked my tripod down and leveled it up, plonked the head on it, then using a hand held compass, pointed it to 11.5° E of S, and using a magnetic inclineometer set the altitude. Just after dusk i looked through the polar scope and to my amazement, There was Sigma Octans within about 4mm of the polarscopes reticle... with 2 minutes of very gentle tweaks, the mount was alligned well enough to keep jupiter on a 1/4" ccd chip for upwards of 2.5hrs at a focal length of over 6300mm...

I think If you can use the polarscope, then you should..

[Ian Robinson]

Helps to know where Sigma Octans is wrt to the SCP at the time you are polar aligning, otherwize you can wind up a fair way off. (ie Transits tonight at 23:28 EAST).

[RobF]

Agreed Ian - I spent quite a while with binocs and my old trusty Nortons before all the kneeling and squinting! Now I've got a good idea where to point can't see myself doing it every night (hopefully my latitude/elevation is pretty good now as mentioned above).

R

[AlexN]

once you have the latitude correctly set, you should only need to worry about azimuth.. and thats pretty easy if you have a hand held compass off relative accuracy.. point the mount ~11.5° east of south and you should be pretty darn close.. :)