Doubts about alignment


Hi all, let me ask the experts a silly question.

I have iEXOS-100 without polar finder nor azimuth adjust adapter, but I have a CCD and I'd like to use sharcap for the alignment.

I can see the polar in the field and it is supposed I have to move the entire tripod to make the azimuth adjustments to align to CP (and the altitude as well . My question is: can I switch on the mount and make the AZ adjustments moving the mount via Cartes du Ciel, p.e., and, once sharcap says it's good or excelent, switch off the mount and switch on again so that the position is reset and being aligned to CP? I know  I have to adjust the altitude manually, but it's frustrating moving the entire tripod to get CP alignment without th AZ adjuster.

Thanks and regards!!

Wes Mcdonald


Hi, please add your info to your signature.

No, unfortunately when you polar align you must move the mount in azimuth and altitude mechanically, not by using the motors.  This requirement is not related to the pmc8 not remembering motor counts when powered off.  Rather, the polar alignment is done to get the RA axis pointing directly along the earths axis of rotation.  When this is done, rotation of the RA axis does not change the fact it is parallel to the axis.  One can get the scope to point to any point in the sky no matter how the RA axis is aligned...but when the axis is rotated the pointing angle relative to the axis will change, which means the mount cannot track stars.

If you are using the iexos for visual, physical polar alignment need not be very good, rather you can use the virtual alignment provided by the 2-3 star alignment procedure built into Explorestars.  What happens is that during the alignment process,  Explorestars computes a model that tells it how to translate between sidereal coordinates and mount motor counts for all places in the sky, even whn the RA axis is not perfectly aligned.  By using this model Explorestars can find objects, and continually adjusts both the RA and DEC axies to point where the object is at any given time -- this is done when EXplorestars is employing "P" mode, for Point mode.  

Explore Scientific does sell an azimuth adjuster ring which can be added to your iexos.  I bought one, and many others have reported they have on the forum.  It works quite well and allows you to get polar aligned in azimuth easily, at least more easily that without it.

Hope this helps,


Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired


Thanks very much Wes. I'll keep trying... and I'll my info.. :)