How do I measure the UP distance in the Dome Slave settings? #60637
Essentially you are aiming to establish the distance from the intersection (pivot point) of the Dec/RA axis relative to the dome "origin" (0,0,0) - where the dome is a hemisphere (ie: assume the walls don’t exist) - this also assumes your mount is polar aligned and facing north or south depending on your latitude.
It’s something of a dark art and I’ll point you to a better thread shortly, but in essence if your counterweights are horizontal, how far up/down in millimeters is the point around which RA and Dec “meet”/intersect relative to the bottom lip of the dome - up being a positive and down a negative number.
Having been through this a few times, I WILL write something up about this as it’s horribly confusing to everyone.
Same idea for north/south offsets as well as east/west - the ease with which you can determine these through measurements is a function of your mount, though you may get luck and find drawings which help you derive them through trig.
NOTE: these offsets are NOT the pier position, which can itself ALSO be different, you are concerned only with where the key axis intersect in 3D space.
Because nothing is ever as simple as it seems in astronomy, there is a FOURTH dimension, being the OTA offset - this is essentially how “wide” is the farthest optical point of your OTA tube is from the same pivot point. To be honest I am not entirely clear I understand this myself but have found that generally if I use the aperture plus the offset from teh RA/DEC pivot point to the saddle plate I generally get it about right.
As you will learn army my own challenges, this all depends on the mount reporting pier side correctly to INDI, the news is not good if you are using a Paramount sadly, the Paramount driver either can't or is incorrectly reporting the pier side so in my case I have had to use TheSkyX to control the dome slaving.... but you’re not, so all good.
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